Hey folks, I have 1988 cutlass supreme classic and the service eng soon light came on a few days ago. I changed the oil had it checked at the garage with computer no warnings are showing. I removed the negative for a few minutes with no change. Does anyone have any ideas on how to resolve this issue?

 

When did the light actually come on? If it was on when you had the garage check the computer and no codes appeared at that time, they could have reset the light then... If they did try to reset it and it still would not go out, IMO, you have an ECM problem... Any big chain parts store (Pep Boys, Advance etc.) should be able to reset the light if there are no codes or issues with the ECM...

 

First, your 1988 car has an OBD I computer system. Stored codes can be reset by disconnecting the battery for a couple of minutes.

Second, the only reasons for the CEL to remain on are 1) there is a code stored in the computer, or 2) the lamp driver module or associated wiring is bad. These cars have a separate lamp driver module that is a small circuit board built into the dash harness. This was done so that if the CEL circuit goes bad, the lamp would come on to so indicate.

Have you verified that you get a Code 12 when you jumper the A and B terminals in the ALDL connector? If so, the system is working.