Check Trans and Engine light (code P1870)

Hello,

I have 1997 Isuzu Rodeo (automatic, 4wd) and Check Engine and Check Trans. light is showing up. Trans. Light is flashing. Not sure what is wrong. Trans. gears seems to be switching fine.

I took it to the mechanic and after inspecting he is getting code P1870 (component slippage). Is this something to worry about. I am planning to keep the truck for a while. Also how much the replacement cost?

Thanks a lot.

Normally if the CEL and tranny light are on it means it has electrical problems. Either a battery on its last leg or more commonly the altenator is on its way out.
-Ryan

I would have a tranny shop familiar with the 4L30E pull the pan and check the tranny out ASAP. I'm not sure how the TCM determines the slippage, but it's ususally not a good sign with the 4L30E. Could be a weak solenoid, band, or maybe accumulator spring? Hopefully you can catch it in time & resolve the issue. These trannys dont hold up well at all if they are not maintained. ATF changes every 25Kmi, or sooner if you want to keep it forever. G/luck
Joel

Normally if the CEL and tranny light are on it means it has electrical problems. Either a battery on its last leg or more commonly the altenator is on its way out.
-Ryan

I have the same problem with a 2000 rodeo ls. I have had it looked at by the Isuzu dealer and both times they got it wrong. I have had the battery checked and it is fine. Im thinking of buying an alternator and having it installed whether good or bad. I don't want to pay for a four year old alternator to be removed and tested, then re installed, only to fail later. Might as well just change it, would be cheaper in the long run.
Heres my question. Would a loose serpentine belt cause the alternator to under generate power and under supply the transmission with adequate signal strenth? Also, if the alternator was under producing current wouldn't you notice it on any other instruments or the radio?

John

I would have a tranny shop familiar with the 4L30E pull the pan and check the tranny out ASAP. I'm not sure how the TCM determines the slippage, but it's ususally not a good sign with the 4L30E. Could be a weak solenoid, band, or maybe accumulator spring? Hopefully you can catch it in time & resolve the issue. These trannys dont hold up well at all if they are not maintained. ATF changes every 25Kmi, or sooner if you want to keep it forever. G/luck
Joel

With the P01870 code the tranny does not go into back up mode. If the soleniod was wonky, would not the tranny go into back up mode. My only experience with this is reading other peoples postings.
My Rodeo has no physical indications of a transmission slippage. Everything changes gears fine. I have traveled 150 k non stop with the check tranny (P01870) light on. it wasn't on purpose.

John

John- if your charging system is putting out 14V with the truck running, you do not have a charging system issue (battery or alternator). If your serpentine belt was slipping, you would also loose your power streering, a/c and cooling system fan / everything that runs off that single belt.
Joel

John- if your charging system is putting out 14V with the truck running, you do not have a charging system issue (battery or alternator). If your serpentine belt was slipping, you would also loose your power streering, a/c and cooling system fan / everything that runs off that single belt.
Joel


I took the truck to the dealer and he suggested to replace the transmission. Also gave me a huge estimate. Then I took the truck to another mechanic and he is driving since yesterday and didn't notice any problem with the trans. He is suggesting not to change the trans. and just drive until it gives any shifting problem. Currently according to the mechanice the check engine and trans light is also not showing up.

Puneet

John- if your charging system is putting out 14V with the truck running, you do not have a charging system issue (battery or alternator). If your serpentine belt was slipping, you would also loose your power streering, a/c and cooling system fan / everything that runs off that single belt.
Joel

I checked my battery at work with a digital voltmeter. It registered 14.32. I drove home which took me 30 mins, and the voltmeter registered 13.7 while running. Is this dip the norm?

The reason I was thinking the serpentine belt was at fault is because I had the belt changed a couple of months ago. I had them order the belt, they said it would be ready in four days. Four days later I went to get the belt changed and they said they did not have it but they had one that was close. When they stretched my old belt and the new belt. The new belt was about a half inch longer. The said the tension pulley would take up the slack. It suddenly dawned on me after reading this thread that my old belt may have already been worn and stretched and comparing the sizes between old stretched belt and new would be inaccurate. Maybe there is not enough tension in the belt to prevent a random slippage.

After the belt was changed the P01870 came on, but not immediately it takes a couple of days or 100 to 200 Kms before the light comes on after the codes are cleared. I'm thinking the lack of tension is not enough to affect the cooling system or other systems, but is enough to have the alternator under produce after a 100 kms.

I am also finding the dealer inept and\or devious (I have already caught them lying twice). I find that the best way to figure this problem
out is discussing this hear before I spend to have the tranny opened up. I appreciate your knowledge and help.


John

I took the truck to the dealer and he suggested to replace the transmission. Also gave me a huge estimate. Then I took the truck to another mechanic and he is driving since yesterday and didn't notice any problem with the trans. He is suggesting not to change the trans. and just drive until it gives any shifting problem. Currently according to the mechanice the check engine and trans light is also not showing up.

Puneet

I was just wondering how your tranny was holding out. I talked to a tranny guy and he said the 4l30e does not trip the check tranny light until it detects three consecutive faults. Meaning on your first and second trip the computer will chalk up the error to a possible missread. On the third consecutive trip the check tranny light will go off. So you can drive a hundred or two miles before your light comes on. Same goes for the check tranny light shutting itself off. I was quoted $5000 Canadian for a replacement tranny(before labor). If I double that I can buy myself a pretty decent used car. . the tranny guy said the P01870 was the "Mystery code" they have a list of ten possible faults that cause that code. The guy said a lot of times its just better to replace the tranny. He quoted me 1500 to 2500 to take down the tranny and find the fault. Life sucks what are you gonna do.

John

Let me know how your making out with P01870

I was just wondering how your tranny was holding out. I talked to a tranny guy and he said the 4l30e does not trip the check tranny light until it detects three consecutive faults. Meaning on your first and second trip the computer will chalk up the error to a possible missread. On the third consecutive trip the check tranny light will go off. So you can drive a hundred or two miles before your light comes on. Same goes for the check tranny light shutting itself off. I was quoted $5000 Canadian for a replacement tranny(before labor). If I double that I can buy myself a pretty decent used car. . the tranny guy said the P01870 was the "Mystery code" they have a list of ten possible faults that cause that code. The guy said a lot of times its just better to replace the tranny. He quoted me 1500 to 2500 to take down the tranny and find the fault. Life sucks what are you gonna do.

John

Let me know how your making out with P01870

Hi John,

Sorry for not replying earlier. Last week I took my truck to the local mechanic and there the light disappeared. He kept the truck for 2-3of days and didn’t see the light. He drove the truck and didn’t feel any slippage etc. He said he can put tranny for 1200 USD. But he suggested not to change tranny now since truck is running fine and there is no slippage problem. He said if the light show again, I should ignore it until I feel any slippage. Currently gears are shifting smoothly.

Anyway this morning light came back. I don’t feel any performance problem so I am planning to drive for a while without getting transmission change. Will see how it goes.

Thanks,
Puneet

just reading this post dont change the tranny
first thing to do replace the filter then get the thing flushed. next disconnect both battery terminals touche the two together for 15 seconds reconnect both of them problem should be gone
if it does come back all you need to replace is the torque convertor

next disconnect both battery terminals touche the two together for 15 seconds reconnect both of them problem should be gone



Really? Does this trick help to clear the tranny codes?

I would assume that touching the two battery cables together would deplete the charge of any smaller batteries that were used for electronic memory storage, thus having the pcm to go to default settings. My question is what happens if you hold the cables together for longer than 15 seconds, could this cause permanent damage.

I check the Haynes manual for anything on torque converters and found next to nothing, does anyone know of any good internet resources on Isuzu torque converters.

thanks for the info 2eyefishclaw


John

just reading this post dont change the tranny
first thing to do replace the filter then get the thing flushed. next disconnect both battery terminals touche the two together for 15 seconds reconnect both of them problem should be gone
if it does come back all you need to replace is the torque convertor

I got filter and fluid chaged. I remember the mechanic told me to disconnect the battery an reconnect it. I haven't tried it yet. Will try soon. He told me the light will disappear. It may come back again. Why do we need to touch both terminals together. Also where can i find info on torque convertor.
Thanks,
Puneet

no harm will come to the PCM you could leave them together fo a year and you will not damage the PCM all your doing is discharging all electronic components it is not a quick fix for anything but a real good way to clear your dtc after you get the tranny flushed and it will also reset the PCM it may run funky for a while because all it goes through a learning process about 1,000 to 1,500 miles

no harm will come to the PCM you could leave them together fo a year and you will not damage the PCM all your doing is discharging all electronic components it is not a quick fix for anything but a real good way to clear your dtc after you get the tranny flushed and it will also reset the PCM it may run funky for a while because all it goes through a learning process about 1,000 to 1,500 miles

hi,
Im new here I just want to know it is also applicable to my Isuzu trooper 3.1 diesel. I have a problem my speedometer is dead and the check trans is blinking. When I replaced a new speed sensor the speedometer works again I think it was already corrected the problem. I notice to my trooper the check trans start blinking again every 1.8 KM over and over again. I think I have to clear the DTC. Is this is the procedure to clear the DTC in TCM?

Thanks,
Nap

I had the same tranny code come up - and it also did not go into backup mode.

I had them flush and fill the transmission fluid. Light came on two more times after that (I reset it both times with no further service) Since then (about 3-4 months ago) the light has not come back on. I suggest trying that before considering a new transmission. I wouldn't change it until you have trouble shifting. If it ain't broke, don't fix it.

I had the same tranny code come up - and it also did not go into backup mode.

I had them flush and fill the transmission fluid. Light came on two more times after that (I reset it both times with no further service) Since then (about 3-4 months ago) the light has not come back on. I suggest trying that before considering a new transmission. I wouldn't change it until you have trouble shifting. If it ain't broke, don't fix it.

hi silver,
I already flush and fill the transmission fluid and also remove both + and - of the battery and touched the two cables for 15 seconds but still the check trans is blinking in every 1.8 KM I ran. The model of my transmission is AW 30-40. My trooper is import from japan Isuzu Bighorn 3.1D 1993 lotus edition. The engine is good and I didn't notice any failure in my transmission. Im here in the philippines I will try to look any shops that have a scan tools to delete the DTC code that stored in the TCM memory. Its kind of weird because it only occured everytime I reached 1.8KM in my odometer still blinkin when I shut off the engine and restart again it will blink again in the exact 1.8KM that I ran. Thanks silver I think there is no problem in my transmission maybe it needs only to remove the DTC in the TCM memory.

My '01 Rodeo LS was having similar problems.

The check engine light and Trans light would come on and would either shut down or go into "limp mode".

My mechanic thought it was the EGR, but after I cleaned it and some money later we found out it was my wiring harness.

They temporarily fixed it by zip tying some of the loose wires secure and since then everyhting is fine.

Im getting a new wiring harness put in next week, but the temp fix has held for now.

Check your wiring harness....

"hi silver,
I already flush and fill the transmission fluid and also remove both + and - of the battery and touched the two cables for 15 seconds but still the check trans is blinking in every 1.8 KM I ran. The model of my transmission is AW 30-40. My trooper is import from japan Isuzu Bighorn 3.1D 1993 lotus edition. The engine is good and I didn't notice any failure in my transmission. Im here in the philippines I will try to look any shops that have a scan tools to delete the DTC code that stored in the TCM memory. Its kind of weird because it only occured everytime I reached 1.8KM in my odometer still blinkin when I shut off the engine and restart again it will blink again in the exact 1.8KM that I ran. Thanks silver I think there is no problem in my transmission maybe it needs only to remove the DTC in the TCM memory."

You don't need to go to a shop to clear the codes. I just bought a scan tool from harbor freight for $40. Just plug it in and after it cycles throught the codes 4 times it will aotomatically reset for you. Here is a link for the tool:

http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=46030

"hi silver,

You don't need to go to a shop to clear the codes. I just bought a scan tool from harbor freight for $40. Just plug it in and after it cycles throught the codes 4 times it will aotomatically reset for you. Here is a link for the tool:

http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=46030

Hi silver,

thanks for your reply. My trooper is 1993 model the scan tool is only fit for 1996 onward.

Cheers!
nap

Oh, my fault. Well, from what I understand, disconnecting the battery for about 15 seconds or so should do the same thing. But I'm not positive. Might want to post a new thread asking that question. I'm sure some one on here knows for sure.

Good luck.

Hello,

I have 1997 Isuzu Rodeo (automatic, 4wd) and Check Engine and Check Trans. light is showing up. Trans. Light is flashing. Not sure what is wrong. Trans. gears seems to be switching fine.

I took it to the mechanic and after inspecting he is getting code P1870 (component slippage). Is this something to worry about. I am planning to keep the truck for a while. Also how much the replacement cost?

Thanks a lot.


I have an 1999 Isuzu Rodeo. Which has the same problem mentioned here. CEL and Tranny light are one, but Tranny seems to work fine (no slipping). Code P1870 was what my mechanic said it was. I had the fluid flushed, but didn't get the filter changed. I was told the fluid was really dirty/old. I had never changed it, and it has 80K miles. The lights still come back on after a while. They didn't change the filter. I was wondering how import. that was?

He told me this code was due to a mismatch in a comparison of the speed at the front end vs. the back end (not his exact words) of the tranny.

I have the same problem on my 95 Trooper. I read on other forms about a voltage spike causeing the problem. Well I just verified it, I hooked up a multimeter to my Batt and drove around a while and every time the check trans light came on the voltage spiked to almost 18v

I had read some of the problems with the check trans light and in my case it was the altenator. When the internal regulator statrs going out it was caising a spike to almost 18v and freaking out my computer causing it to go into "limp mode"off and on about 3 times in a 2 block distance. Changed out the altenator problem gone. Now the cause of the altenator going bad was probably because of the great idea of putting the altenator below the power steering pump so any leaks go right into the altenator. Fixed the power steering pump leak got rid of the oil soaked alt all is good.

This just happenned to me yesterday. The light started flashing on my commute home. Actually on Sunday, at the beginning of 260 mile round trip, I had thought it was shifting wierd (or not engaging the mechanical lockup when I was used to.) The rpm's seemed different than I remember given the speeds the truck was going. The rest of Sunday's ride, and all day monday, even after the light started flashing, the truck seemed better, Shifted where I remembered. RPM's even dropped when the lockup engaged.

I checked the computer codes this morning and it was P1870.

I then had the transmission flushed, and then the filter changed - took much longer than the shop thought it would since they didn't realize they'd have to unbolt one of the cross memebers to get the pan out.

I'm very encouraged to hear some of what's being said here. I think I have reason to suspect an electrical problem too, Hopefully someone can help me figure out what to do from here...

For a while I've been wondering if my alternator was on it's way out. Over a year ago my battery wouldn't hold a charge (original battery) I had it tested and replaced, and had the alternator tested too. It passed, which surprised me since at idle the interior and dash lights, and radio and clock LCD backlights, all flickered noticeably. But it passed.

Lately I haven't been sure, but I've been thinking the flickering is getting worse. It seems to diappear when I hold my foot on the gas and boost the RPM's.

Anyway, given this electrical problem is it worth replacing the Alternator before I go and spend a ton of $$ on the tranny? Even if the Alternator passes it's tests?


Any other advice? How does it compare pricewise to replace a torque converted instead of a whole transmission?

-Kyle

...
For a while I've been wondering if my alternator was on it's way out. Over a year ago my battery wouldn't hold a charge (original battery) I had it tested and replaced, and had the alternator tested too. It passed, which surprised me since at idle the interior and dash lights, and radio and clock LCD backlights, all flickered noticeably. ... I've been thinking the flickering is getting worse. It seems to diappear when I hold my foot on the gas and boost the RPM's.

well something is not right with your charging system. top suspect is the alternator. depending where you got it tested, like at a bigboxpartsstore, the test might not be indicative of what's really going on.
but your flickering and steady with increased rpms does indicate a charging system problem. but it just might be the belt not adjusted and/or battery cable connectors and/or grounds, which might be the thing to check out first.

that's where i would start anyway...

//bc

Ok, this thread is so old it starting to mold. Usually it would be good to start a new thread with a reference to this one.

Over 5K views, though.

I have a 1993 Isuzu Rodeo. Check tranny light was falshing about 2 months ago and had a grarage hook up diagnostic machine for $75. He told me it was the alternator amongst other things. I changed the alternator only and that fixed the tranny flashing light problem.

It ran fine.......
NOW I have the "check engine" light on. Advanced auto and Auto Zone's tester starts with model year 1996 and above.
My question is, IS there a way I can find out what is triggering the "check engine" light without going the $75 route again to find out?

I have read in the owners manual that it is something to do with the emission system. Anybody have any expirence with that??
Any help is appreciated.
k

yes, for the OBDI system (pre1996) you just jumper two connectors with the engine off ignition on and 'read' the flashes counting each flashes as a pair, for example 12 (which is the first one to show you the system is working) is one flash pause flash-flash (which is 1 and 2, which is 12).

only problem is i don't know where the connectors are in your rodeo,...try a search here.

btw, you might have better luck on something like this starting your own thread, to get quicker and better responses...

//bc

bc, thanks for the info. Do you think the EGR could be the problem or does a 1993 Isuzu Rodeo have oxygen sensors tha tcould be an issue? The "CEL" doesn't come on right away it takes 10 to 15 miles before it rears it's ugly head. Seems like it has to warnm up pretty good. The temp gauge is good.

Thanks for any help.
k

http://library.alldatapro.com/alldata/LIB~C20520~R0~OB0~P3R0H~N/0/41746052/56622331/56622417/56622418/34853741/34857029/34857030/34857663/81127337/81128155/85876136/62628348

DIAGNOSTIC TROUBLE CODE (DTC) NO. DISPLAY

When the DTC test lead in the vicinity of the ecmis connected with the ignition switchturned to ON position, the diagnostic trouble code stored in memory is displayed in the MIL.
With the engine not in operation, first, the DTC 12 is indicated three times, which means that the ecm is functioning normally. Then other DTCs indicating other malfunctions, if any, come on three times each in the ascending order of DTC numbers.
The malfunction DTCs are also read out when the engine is running. In this case, the DTC 12 is not indicated.http://library.alldatapro.com/alldata/LIB~C20520~R0~OB0~P3R0H~N/0/41746052/56622331/56622417/56622418/34853741/34857029/34857030/83370404/34857583/56661034/41972741

I don't think there is an 1870 code for the engine that far back. Once you ground the DTC the flashing CEL will give you a two digit code. If memory serves, 32 is code for egr problems.

and the codes are *stored*, usually. so the light doesn't have to be on for you to read the codes that are stored in memory. after you do the reading, clear the memory by disconnecting your battery for 30 seconds so that you can retest for any new codes set; otherwise you will be reading the same old code.

egr valve can be an issue. and you do have a single 02 sensor which can be an issue. read the codes and go from there. imo.

//bc

Atfdmike and bc, both of your post is very good. Unfortunately they are a bit over my head in understanding them. A couple of Q's for both of you if you don't mind.

"When the DTC test lead in the vicinity of the ecmis connected with the ignition switch turned to ON position, the diagnostic trouble code stored in memory is displayed in the MIL."

Mike- What is ecmis and do I connect it with the DTC test lead and if so how do I do that?..... and where is the MIL?

Once you ground the DTC the flashing CEL will give you a two digit code. If memory serves, 32 is code for egr problems.
Mike- What do you mean by ground and how do I do it?..... and where will the code be displayed?

and the codes are *stored*, usually. so the light doesn't have to be on for you to read the codes that are stored in memory.

bc- What light doesn't have to be on?.... where is the light located and do I clear the codes by disconnecting the battery first before a jumper it?

Sorry to be so thick headed. My father was a very good electrician but I did not get any electrical ability from him unfortunately.
Thanks for your help guys,
k

I have a 2001 Rodeo. Last July the Transmission light and check engine light came on together. We were going about 72 mph. Pulled over, turned the truck off then back on. Took off again - discovered that we were okay at about 68 mph - anything over that for a long period of time and the lights would come back on. The transmission would not stay in overdrive. Had to have transmission rebuilt - now it's better than ever. Only have 85000 miles.

RodeoJ - did you have your alternator tested for output *before* you replaced your transmission??

I can't even count how many people were told and could swear their trannies were failing, when in fact the alternator wasn't putting out the power to force the shifts. These Isuzu's are voltage happy vehicles and will behave oddly, even sickly, if they're not getting enough juice.

Sounds like there is good used 4L-30E out there with only 85K on it...

I did not have my alternator checked first. Could a bad alternator have caused the damage to my transmission? I truly trust the mechanic that fixed it and do not believe I have been taken advantage of. When going 65 the RPMs were over 3000 - now they're just above 2000 at 65-70.

I did not have my alternator checked first. Could a bad alternator have caused the damage to my transmission?no. bad alternators on isuzu's create lots of weird symptoms and problems, like with the fuel pump, with dash lights and with weird automatic transmission acting up. but it's not so much that a bad alternator would damage the transmission as that a bad alternator might be mistaken (knowlingly or unknowingly) as a bad transmission. in your case, it's water under the bridge, and you've said the rebuild solved your problem -- so that's that. you will probably hear that the 4L30E automatic transmission doesn't seem to take kindly to rebuilding, but again, that's done, so just take good care of it with fluid and filter changes...and enjoy.

I truly trust the mechanic that fixed it and do not believe I have been taken advantage of.

that's great. care to share?

When going 65 the RPMs were over 3000 - now they're just above 2000 at 65-70. just curious, what did the mechanic say was the specific problem?

thanks


//bc

The shop I went to is Metro Transmissions in Columbus, Ohio. I believe it is family owned. They also adjusted the bill to stay within their original estimate.

The exact problem was that the overdrive clutch was "gone". We replaced the clutch, torque converter, gaskets, solenoids, etc. :2cents: eek:

Thanks for your comments!

Have read all your threads with interest. About once a week my 1999 Rodeo Check Trans light starts to flashes when you go to start it up. You have to wait a minute then it starts OK.

It's been to the mechanic twice, last time it had the filter changed, tranny flushed he said all is fine. Problem occurred again so took it to the autotransmission guys - and they couldn't find a problem. Recently had to change the battery, and he checked alternator and said all is fine (which now makes me wonder is it really OK).

Mechanic at Holden said that it might be something to do with the wiring - next time it happens call them and they will see if they can fit us in, which is handy if they can't.

I think it's an electrical problem more than a tranny problem, but where do I start, replace alternator or look into the wiring? Any suggestions would be greatly appreciated.

Thanks & Regards :banghead:

P1870 trans component slipping
usually indicates that the torque convertor is starting to fall apart (internally)
sometimes flushing the trash out of it will help for a while but its only a temporary fix for major trans damage best bet is to flush trans replace torque convertor and flush trans again

I had the same code come up with the tans light flashing, also the lights on the gear selector would indicate "N" even though we where in "D". After doing many of the checks like pulling the alt. off to check it's output and haveing the battery checked which all came back ok. I also took it to a few shops that said that I would have to change out the tranny. Not wanting to just fork over that kind of money I did a bit more research and found a local guy who was highly recomended by many. What he had found to be the problem was the range position sensor to be at it's maximum available adjustment. Hhe replaced it, changed the trans filter and new oil and now all is well. Better downshifts and response.
Do your research before allowing anyone to tell you that you will need to replace such an expensive part. A tranny should not be needing to be replaced so soon unless you have never taken the time to take care of it.

OK, I have a 1995.5 Isuzu Rodeo (same 4L30E transmission--YUK!), and I've recently had the "Check Trans" and "Check Engine" lights both come on, at separate times. I had the error codes read, and though I didn't get error code numbers for the transmission, they said the errors pertained to the TCC and shift solenoids. Does anyone happen to know the codes for those, on the OBD-1 system?
And also, could I correct such a problem just by changing the A/T fluid? Since not being able to drain it out completely doesn't help any, and since I haven't been able to get an accurate reading on the dipstick, I'm switching to Plan B-- install a drain plug in the pan myself.
Anyone have any better ideas?
Thanks!
BTW--the engine error code was 44, which is "System Lean Driveability". Anyone have any suggestions on how I can take care of that before I have to get ready to pass my smog test in December?
Thanks again!

I wish I had a dipstick for my 4L-30E!

BTW--the engine error code was 44, which is "System Lean Driveability". Anyone have any suggestions on how I can take care of that before I have to get ready to pass my smog test in December?
Thanks again! mmmm, didn't you say it was a code49 over planetisuzu (kittysmom, right?)? which there isn't for isuzu.

code 44 for isuzu is for "Heater Oxygen Sensor Circuit" not the generalized one that neighborhood shop gave you. still not taking it to the dealer to get the trans codes read?

//bc

I have had a 1993 trooper for 6 months now, the check tranny light comes on pretty much everytime I drive it, but everytime I turn the car off it turns off and takes few minutes. It almost acts like it needs to shirt between 1 and 2nd gears few times and then the light starts blinking. The tranny has no slips as long as I shift it with the shifter like a manual stick. But if I leave it in over drive, it will stay in 4th and never shift down unless i do it manually.

I took the car to repspected tranny shop, it spit out code that said needs 1-2 3-4 shift solenoids. $500 later, the light still stuck on. I also did some research and the code said maybe the hot wire going to solenids is grounding out somehwere on way to tranny, I'm gonna power wash down below and see if I see something but I'm stuck.

anyone else got any ideas?

You need to get the code that is set in memory when your trans light comes on. You can do this by jumpering the DTC connector and counting the flashes of the trans light as it blinks. For a 93 the manual shows the connector to be a brown one on the hump where the carpet meets the console. Jumper the two outside pins and turn on key....Don't start, and read the code(s) that flash. ONce you have seen the same code twice, that means all the codes have been read and it starts over. Post the code. The trans is shifted electronically but the mode switch has to be set right and the input from the ECM to the TCM must also be right for shift speeds to be right. I guess it is possible for something like the speed sensor or a dirty or broken Mode switch (mounted on trans shift input lever) to make the trans mis behave. HTH One guys opinion.

Wow! Over an almost EIGHT YEAR period, and so many people, all having the same problem with their Rodeo! I also have a 2000 model Rodeo 4WD with the 3.2 V6, and I also have the same problem with the CEL and Trans light flashing. The CEL has been identified by the PCM as an EGR problem, and there is also an EVAP system problem, intermittently. This makes sense, because when I fill up the fuel tank, I can smell gas fumes inside the vehicle....

This tranny light situation seems to be VERY COMMON with these vehicles, and it is little wonder that Isuzu Motors is no longer in business. Mine came on at highway speed, after passing another vehicle, and the same code (P1870) came up with the OBD II Code reader. The transmission shifts fine, is not low on fluid, and does not go into "limp mode".I keep on canceling the code when it shows up, and the check trans light starts its thing.
Noticed the wiring harness fix mentioned earlier, and wonder if that could be a cause on all of these vehicles. Some of these posts are pretty old. I would be interested to know if anyone has found a sure fire fix, with no repeat of the light coming on.

Darryl

Earlier this year, my friend's 2000 Rodeo was going into limp in mode (reduced power and only 20MPH) and the trans light would flash. Pulled the trans out for a build after I discovered almost no fluid in the pan due to leaking cooler hoses from loose clamps and lots of clutch material in the pan. At first, I was just going to service the tranny. Rebuilt the box and put in a rebuilt converter, flushed the cooler 3 times in each direction. Added a dip stick from a 1992 Rodeo I found at a local wrecking yard by drilling a 3/4" hole in the case from the bottom side. It worked great until about a month ago when he took a trip down to Mexicali for 12 days with the wife in tow. After they got back, the trans light came on again! After the build, I noticed that at idle the dash lights would pulse at idle, and figured it to be a bad alternator as they would stay bright when revved up a bit. He told me later that the flashing dash lights was due to the factory alarm system, and he couldn't get it to shut off, so he just disconnected the horn so it wouldn't make noise when driving it.
So now I'm wondering if his alternator is indeed going out, making voltage spikes and raising havoc with the TCM. We took it out last Saturday morning for about an hour, going up and down some VERY steep roads in the mountains and couldn't get the light to come on. I left him my scanner to see if any codes would show up when the light came on, but nothing showed even though the light came on! Now I'm beginning to think that the alternator voltage regulator is bogus.
Randy