ways to check codes on older cars.

hey, i have an 88 park avenue, and when i purchased it in march of 08 the check engine light has always been on. I bought the car from a trusted friend, who bought the car from an elderly person a few months earlier and he said that he doesn't know why the check engine light is on, but the car runs fine. The car does run fine, and i haven't had any major problems out of it yet, so im confused as to what is the problem, and how would i check. i went to autozone for a free diagnostic, but they said my car was too old and something about an OBD scanner for years after 1996. Am I out of luck, or is there some type of way to check why the check engine light is on. Also, the spark plugs aren't really in good shape, could that be a reason as to why the check engine light is on?

The connector is under your dash on the driver's side.
http://i41.tinypic.com/28urbj7.jpg
To start, get a jumper wire or paper clip and insert one end in the A terminal, the other in the B terminal. Turn the ignition key but don't the car. The light on the dash will start to flash. You need to count the flashes to determine the codes. The first flash to come up will be 12, one flash followed by 2 flashes. This is a diagnostic code to let you know the system is operating properly. It will flash 3 times before any stored codes will appear. The codes will flash for three times before going on to the next one if any. If no other codes presents other than 12 then there are no stored codes. Write down the codes and then post them here to find out what they mean.
I would start by getting the codes before starting any parts replacing or diagnosing.

Is it possible to check the codes without a scanner then ?:bloated:
How does this work on a 91 PA ?

Yes, it is very possible-- what is really funny is that Autozone hands out for free the little keychain jumper plug that fits into your pre-1996 ALDL plug under the dash. I carry mine on my keychain still- have had it for about 10 years.

This works the same way on all GM vehicles-prior to 1996, so your 91 PA will respond the same.

Can you also check codes when the 'check engine' light isn't on? Which light is flashing?

Can you also check codes when the 'check engine' light isn't on? Which light is flashing? Follow the instructions in post #2!

This works the same way on all GM vehicles-prior to 1996, so your 91 PA will respond the same.
The procedure in post #2 will not work on most 94-95 GM cars, especially Buick’s!

The connector is under your dash on the driver's side.
http://i41.tinypic.com/28urbj7.jpg
To start, get a jumper wire or paper clip and insert one end in the A terminal, the other in the B terminal. Turn the ignition key but don't the car. The light on the dash will start to flash. You need to count the flashes to determine the codes. The first flash to come up will be 12, one flash followed by 2 flashes. This is a diagnostic code to let you know the system is operating properly. It will flash 3 times before any stored codes will appear. The codes will flash for three times before going on to the next one if any. If no other codes presents other than 12 then there are no stored codes. Write down the codes and then post them here to find out what they mean.
I would start by getting the codes before starting any parts replacing or diagnosing.

i checked my car, and the connector is in the middle of the dash, a little behind the ashtray. now when i put the wires in, do i place them in spots that are closers to the passenger side(right side of the vehicle like in the above diagram), and on the back row, or will i have to position my body in a way in which the diagram is different. sorry if you don't understand what i mean, but i can try to clarify better if you ask.

Also, can I use some speaker wire instead of a paper clip?

If the speaker wire is unbraided it will probably work as a jumper.

People that drive a car with the check engine light on because it seems to run fine run the risk of incurring very expensive repairs down the road like transmission failure from a faulty TPS or plugged catalytic converters from other emission failures etc.

Observe the flanges and end holes on the ALDL connector. They will indicate the orientation of the connector and pins.

Insert a jumper tool or the aforementioned paper clip into the 'A' and 'B' terminals on the ALDL connector:

http://mysite.verizon.net/strey/files/ALDL.gif

WITHOUT STARTING the engine, turn the ignition to the "RUN" position. Watch the Malfunction Indicator Lamp (MIL) - it will begin to flash. This is also commonly called the “Check Engine”, “CEL”, "Service Engine Soon" or "SES" lamp. The first code will flash three times, and will usually be a code '12'. This is encoded by one flash of the lamp, a brief pause, then two successive flashes of the lamp. Each code will repeat three times, so you should see a "Code 12" flash three times. Any other error codes will follow in numerical order, and each code should flash three times. After all codes have been displayed three times, the "Code 12" will again flash three times, then all other codes will follow as described earlier. This cycle will continue until the jumper is removed or the ignition is turned off.

After you have made a note of all error codes, turn off the ignition and remove the jumper immediately. Check your resulting error codes here:

GM Error Codes (http://mysite.verizon.net/strey/files/GMError.pdf)

thanks for the feedback everybody. i did it, and got a code 15(flashed once, and then five continuous flashes). i checked a error code website, and it said a generic code 15 means coolant temp/low temp.


since this part of the forum is strictly for park avenue, i wanted to check in here first and see if thats the right code for an 88 park ave.


could this be the reason why my heat never gets hot in my car?

I would put a new thermostat in