FYI - For those who haven't seen an ECM

I just ripped a '93 Geo Metro 3 cylinder, 1.0 L Electronic Control
Module (ECM) out of a "Pull-n-Save" vehicle yesterday.

WHAT A JOB! VERY hard to get at..... But now I have one for $8.

So I opened it and took some photos with my old digital camera that
only has 810 KB, so the image isn't up to professional standards.

The images download from "ImageShack.com" so if nothing is on
your screen, then ImageShack is down........

Here is the Lid with the numbers on it.

http://img524.imageshack.us/img524/5592/ecmlid6qc.jpg

This is what is inside - a lot more than I expected!

http://img524.imageshack.us/img524/7703/ecmelectronics1kf.jpg

Size is 6.375 x 5.50 x 1.25 inches not including three brackets.

Medium book size. Weight is 1.33 lbs.

New they are in the range of $1,500 if one can be obtained.
Used - up to maybe $40 (?)
Remanufactured - $240 plus shipping (with core sent back)

I was curious and I thought maybe others are also.

DoctorBill

I warned you we are too old to be standing on our heads!!

Where are these boogers located at?

I kinda think mine may be acting up. It acts like it's a little slow on backing off the fuel supply, after start up. My ECT Sensor, Injector and the TPS are all new, so I'm thinking it's in there. I went completely through my Throttle Body this morning and cleaned it out completely. It was pretty messy, inside where the air valve assembly is and the base gasket was not in too good of shape either.

"Where are these boogers located at?"

The Chilton Manual says '93 and back are under the dash on the
driver's side. The one I took was on the left side of the firewall under
the driver's side dash right behind and to the left of the fuse box.

'94 and up are supposedly behind the glove box.

The ECM in the '93 in the YARD was Hell getting at!

"I went completely through my Throttle Body this morning and
cleaned it out completely. It was pretty messy, inside where the air
valve assembly is and the base gasket was not in too good of shape
either."

Tell me all about taking the Throttle body apart...!

I took the air cleaner off mine to photograph the Sensors attached to
it and a lot of crap is on the metal parts!

If I could disassemble the thing w/o totally screwing it up, it would be
a good experience. But I'm too afraid of "totalling" my Metro!

Where do you get the gaskets from and how much $$ ?


DoctorBill

Good question, Doc. I've been thinking of tearing my TB apart as well. Would like to hear any gouge from leon, or anyone else for that matter regarding same.

I checked around for a TB gasket set. Dealer was the only one that had it for about $53.

94 was the last year of the MK3 body. they didn;t put it behind the glove box until 95

$53 for a gasket set!

Could one cut the gaskets out of gasket material one's self?

Hobby Razor - Scalpel etc...?

DoctorBill

I did it yesterday, and everything turned out good. About 6 bucks for me. a couple bucks for gasket sheet and a couple more for the carb cleaner. I picked up another 5 miles to the gallon the first day I drove it. The air valve assembly cap was not all the way seated, so that is another thing to watch out for. Use a spanner wrench to remove it, and clean all the parts inside, completely. That's about all there is to it. I poured me a cup of coffee and went outside to do it. I had it all torn down, before the coffee cooled down. LOL I still have troubles running rich., so I'm installing a new FPR tomorrow. These are nothing more than a diaphram, an inch in diameter, so I can see why it would be good to change them out periodically. If they're no longer flat, or cracked, then they need to go. They put them on top of the throttle body, for easy access, thankfully. Anyhow, good luck with everything. I'm heading off to a barbeque.

On E Bay there are some guys who fix the ECM s for 70$ money back guarantee I used them twice no problems but I lost the E Bay user names do.
At my local junkyard I picked 2 of them one for 25$ and one for 35$.
Usually they don t go bad easy , but is easy to blame them for certain malfunctions.

I did it yesterday, and everything turned out good. About 6 bucks for me. a couple bucks for gasket sheet and a couple more for the carb cleaner. I picked up another 5 miles to the gallon the first day I drove it. The air valve assembly cap was not all the way seated, so that is another thing to watch out for. Use a spanner wrench to remove it, and clean all the parts inside, completely. That's about all there is to it. I poured me a cup of coffee and went outside to do it. I had it all torn down, before the coffee cooled down. LOL I still have troubles running rich., so I'm installing a new FPR tomorrow. These are nothing more than a diaphram, an inch in diameter, so I can see why it would be good to change them out periodically. If they're no longer flat, or cracked, then they need to go. They put them on top of the throttle body, for easy access, thankfully. Anyhow, good luck with everything. I'm heading off to a barbeque.

Tell us what you did! How far did you disassemble the TB and were
there any parts that would go flying if one isn't careful?

Did you just do the top or did you go all the way down to the bottom
to the intake manifold? There are two parts to the TB....
See diagram from Chilton below:

http://img474.imageshack.us/img474/8854/metrothrottlebody27de.jpg

Did you have this diagram to go by, or did you wing it?

What did you find - a lot of crap? What kind of stuff did you find?

I am fascinated....

My Dad disassembled a carburetor when I was in college and got it
back together OK. I never had the nerve to do something like that!
Now that I'm 63, I wonder if I could see well enough to do it....

DoctorBill

From what I found, the throttle body is simpler than a Carburator. And no....I didn't have any parts go flying. I did look at a diagram, and it helped me see some stuff on the air valve assembly. The top half comes apart from the bottom half from the two front bolts and all the phillips head screws. The two rear nuts hold the rear half to the intake. This diagram doesn't show the air valve assembly, strangely enough, but it is right below the ECT Sensor and goes in from the bottom of the throttle body. There is usually a bunch of grease and grim to be found in there, on a well used throttle body. I would just unscrew the little spanner cap, on the bottom and completely clean the parts with carb cleaner, then clean up the outside of the body as well. That is about all there is to doing the bottom half. I found there is very little to deal with on these little throttle bodies. Infact, about half the parts as a regular carburator. It's just a matter of cleaning it up, and replacing the gaskets, is all a person really does to rebuild one. My base to manifold gasket came apart in pieces, so I had to make a new one. The center gasket was fine, so I was able to reuse it. In the top half of the throttle body, again, just clean everything up entirely and replace the FPR Diaphram. The injector, is about the most expensive part of the thing, but I wouldn't worry about that, unless you still have a problem after the rebuild. The Haynes manual tells how to check one and it seems pretty simple. I'm puting in a new FPR today, so I'll see what that does for it. The rebuild gave me about 5 miles to the gallon, so that was a step in the right direction. It's still loading up bad, at cold start, so I think I may have trouble in the ECM. It isn't throwing any codes, so I think troubles are where it can't read, or the pulse width needs to be reprogrammed. It seems like the pulse width should be backing off more than it does, once it starts up, but it just loads up and runs crappy at start up. Once it is warm, it runs really good and drives smoth, but I do hear some pinging, so, I can tell, it's still getting too much fuel. I believe something in the ECM, that controls the injector duration (pulse width) is out of whack, like the duration is too long. Oh well, I planned on making this a rebuilder and now it has all new components on it. This summer, it's getting a total rebuild in the engine, so I'll have solid transportation for years to come.

Thanks for posting the pic of the internals of the ECM. My guess is that the square IC on the right (black object with silver legs) is the micro - you can see the crystal for the micro's internal clock just below. There appear to be a number of smaller ICs dotted around - they look like line drivers or something similar for the data buses. On the top left the 3 legged device looks like a voltage reg mounted to a heat sink for power dissipation. I can also spot a few transistors as well as an assortment of resistors and caps. I can also see a large diode in the middle. The raw cost of these components are not worth more than about $50. What a profit margin if they do sell them for $1500!!

If you can take close up of that square IC so that the part no is visible I should be able to track it down an provide an idea of its computing power.

I talked to a Geo Metro owner here in Spokane who works at a muffler
shop.

He removed his TB Injector and took it to a local carburetor shop and
the guy rebuilds the injector. He said it improved his mpg and
performance.

Apparently Schucks sells a TBI rebuild "Kit" for around $68. #5031
http://www.partsamerica.com/ProductList.aspx?CategoryCode=3575M&SearchFor=Fuel%20Inj%20Throttle%20Body%20Rebuild%2 0Kit

"Holley Pro-Jection Renew Kit: 1-bbl replacement TBI's; 1-bbl Pro-Jection systems.
Pro-Jection Renew Kit: 1-bbl replacement TBI's; 1-bbl Pro-Jection systems"

Image:
http://www.partsamerica.com/ProductDetail.aspx?categorycode=3575M&mfrcode=HOL&mfrpartnumber=5031
Looks like it has a Fuel Pressure Regulator Diaphragm as part of it.

I just ordered the FPRD alone for $32 from Schucks. Hope it comes
with the spring. They get rusty.

I may try to find this carburetor repair shop and see what he charges
to 'rebuild' the injector...

Anyway - you have me intrigued about taking my TBI apart.
I actually went to Schucks and bought a sheet of gasket material...!

Mine was so full of crap at the top with the air filter removed.

DoctorBill

Thanks for posting the pic of the internals of the ECM. My guess is that the square IC on the right (black object with silver legs) is the micro - you can see the crystal for the micro's internal clock just below.

If you can take close up of that square IC so that the part no is visible I should be able to track it down an provide an idea of its computing power.

I just re-opened it to read off the numbers....as follows:

-----------------
D
151802 - 9484
76C75T - 3129
2A1077
JAPAN
-----------------
The 'DOT' at the upper left corner is painted (paint) pink.


The crystal is numbered:
|2.ONDK'2|

"On the top left the 3 legged device looks like a voltage reg mounted
to a heat sink for power dissipation." THAT has the following #:

ET424
21

Does that help.......?

DoctorBill

Hmmm...looks unfamiliar - most ICs usually have a manufacturer name or marking - looking at the photo this seems to be absent. It could have been a custom job for Suzuki using a well known micro core like the ARM. I will look up the part numbers and see if I can dig anything up on it. The crystals usually have a frequency marking on it - again the marking on this is unfamiliar but the 2 suggests that it could be a 2MHz xtal. This would suggest that the micro is quite a primitive one (as I suspected) - contrast this to the latest processors that run in the GHz range but should be more than adequete to control an automotive engine.

Hmmm...looks unfamiliar - most ICs usually have a manufacturer name or marking - looking at the photo this seems to be absent. It could have been a custom job for Suzuki using a well known micro core like the ARM. I will look up the part numbers and see if I can dig anything up on it. The crystals usually have a frequency marking on it - again the marking on this is unfamiliar but the 2 suggests that it could be a 2MHz xtal. This would suggest that the micro is quite a primitive one (as I suspected) - contrast this to the latest processors that run in the GHz range but should be more than adequete to control an automotive engine.

OK.....

Here are some more things I read off the PC board:

All of the rectangular chips (memory?) right side and bottom of the
picture are TOSHIBA OR ND.

Toshiba #'s

TC4066BP
9206HB SMALLER LETTERS

74HC04AP
9149H SMALLER LETTERS

74HC4024P
9201H SMALLER LETTERS

TC4093BP
9201H SMALLER LETTERS

TC4066BP
9206HB SMALLER LETTERS

ND #'S

SE081
1M30

MF680
1M27

The vertical in-line things (Far right top & lower left bottom) are
ND SE185 2M03
and
TOSHIBA T2333 9207K
respectively.

The big round/Flat diode far left middle says:
T S5225 2*A
WHERE the * = a dot.

The green rectangular thing next to the heat sinked ET424 has
105K100
Japanese symbols

If you have a local Pull-n-Save, you can get one for a 'pittance'.

Mine cost me $8 - but was hell getting out.

Take a ratcheting socket wrench, a 12 " long extension rod and a 10
mm socket as the bolts have phillips heads and are 10 mm six sided
and are hard to loosen with no room to manuever your hands in
all those wires underneath the dash on the driver's side.

If mine goes south, I am going to hate trying to change it out!

I am still sore from getting this one out.... I'm 62 and less flexible
than I used to be.

DoctorBill

Yes, I recognize a few of these. The ICs starting with 74 are "glue logic" ICs. They generally contain a few gates (for example the 74HC00 is a quad NAND pack) and can be used to invert and perform basic logic operations when a much larger device is not needed or another device does not output the signals in the desired format. The 74HC04 is a quad inverter pack - not sure what the 402 is - need to lookup a 74 series book. Many semiconductor manufacturers make the 74 series - not just Toshiba. In fact before large scale integration that we have today equipment were sometimes enirely made out of 74 series chips. I did design part of a video frame store and image processing engine for the D-MAC video encoding scheme in the late 80s entirely out of the 74 series chips.

These days we would just use a very small FPGA or CPLD instead of these chips.

The 4000 series in another bunch of chips (I think they are based on ECL technology - not CMOS or TTL like the 74 series). The 4066 is a quad solid state switch (just like a relay).

Don't recognize the other parts althogh I suspect many of them are the Japanese equivalent of the generic parts that we make over here in the US. From what I can see it should be possible to repair a simple fault since many of the devices are available off the shelf although a Japanese - US cross ref guide will be required. Also a schematic would be sueful although the circuit could be drawn by looking at the board as it does not look very complex.

Hey Guys. I'm thinking about looking in my ECM and maybe testing some of those components. Anything I should look for? I've changed everything else and the problem must be there. I wonder which leg controls the fuel supply.

First step would be to see if you can get a pinout of that white connector and figure out which line controls the fuel supply. The service manual hopefully has this info. Then take the ECM apart and look for any obvious problem like cracks on the pin, any damaged, burnt components and anything else that is obvious. If possible try to draw out the circuit of the relevant part of the ECM on paper (by inspecting the circuit board) and aside from the micro and the glue logic chips, the other components should be testable with a multimeter. You can test the smaller chips with a multimeter provided the signals do not change too fast – if they do then you will need an oscilloscope plus some idea about the waveform.

Hope this helps.

The other thread on ECMs reminded me to post this info on the micro which I dug out a while ago but never got around to posting. From what I can gather it is a Mitsubishi part and is based on the Motorola HC11 micro which is a simple and popular device. However, it is not obvious if the Motorola development kit for the HC11 would work on this device. I did see on the net that some people had been able to read the LUTs and modify the performance characteristics but I did not look into how this was done. However, the same thread did have a printed listing of the tables.

Could not find any documentation on the Mitsubishi part so I guess it is a custom device for the auto manufacturers.