88 Sub check engine light

My 88 sub check engine light comes on after it runs on the highway for 1/2 hour or so. I shut the truck off and it clears. I drive 1/2 hour to work some interstate and some city. The light never comes on. How can I check the codes?

Thanks

Probably a code 32, EGR system.

Probably a code 32, EGR system.

Thanks I will do a little homework and check with Autozone to see if they can test or verify the code error.

Thanks I will do a little homework and check with Autozone to see if they can test or verify the code error.
AZ cannot scan a pre 95 vehicle.

www.troublecodes.net/GM

//2000CAYukon

You’ll need to acquire a GM ECM Diagnostic Trouble Code Retrieval Tool. (Most of us just call them “paper clips, but GM has to have some fancy name for them to charge more.) Cut the clip in half so that one end of it is still bent in a “U” shape. If you’re careful, you can make TWO error code retrieval tools from one paper clip.

With the engine and ignition turned off, locate the ALDL connector under the dash, just to the right of the steering wheel in the driver's foot well area on some models, and on the left on others, depending on the make and year. There may be a small rectangular cover over the access hole in the lower dash trim.

http://72.19.213.157/files/ALDLPlug.jpg

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

http://72.19.213.157/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. If you forget to remove the jumper and attempt to start the engine with it in place, you could damage the ECM. For this reason you should remove it immediately.

Once you have a note of all error codes, check this file for the decoding:

GM Error Codes.pdf (http://72.19.213.157/files/GMError.pdf).

You'll need Adobe Acrobat Reader (http://www.adobe.com/products/acrobat/alternate.html) to open/print the file.