Intermittent SES light

[Dds1990]

Want to ask for some help on 1990 Red/Red #0106. Took it out for the first long drive and started having the SES light come on for a short while then go off. Once it goes off I still have full power. I checked it with Cliff's ALDL Code reader and during 4 checks I got 2 Code 36-DIS Circuit (missing or extra EST signal). Then on the second two checks I got Code 12. Seems I had this problem a couple of years ago and replaced the battery. The current battery was fully charged before I took it out. Any help would be great.

[Hib Halverson]

There is a engine controls harness connection to the DIS module underneath the plenum at the rear. The connector is held in the DIS module with 1/4-in head head bolt.

Unscrew that bolt, remove the connector and clean the connections.

You may need to remove the MAP sensor to access that bolt.

Also, make sure the spark plug wires are not close to the wires in that harness.

If the problem persists, I'd get the 1990 FSM and follow the diagnostic and repair instructions for that code. To do that, you'll need a DVM and a test light. The solutions are likely: 1) wire and/or connection problems, 2) bad ECM or 3) bad DIS module.

Hopefully your DIS module has not failed.

Good luck!

[Paul Workman]

Yup, and while you're at it, the two main ground lugs for the bulk of the circuits are attached to one of two bolts at the top of the motor, just under that DIS and MAP stuff. Just to eliminate a host of future 'gremlins' ("while your in there...") it is a good idea to "R&R" the ground connectors with a wire brush or emory cloth and then a coating of dielectric grease or the like to prevent oxidation (now and in the future!).

NOTE: I always suggest that ppl first tie-wrap those wires attached there into respective bundles as they can pull away and be difficult to corral again.

[Hib Halverson]

Originally Posted by Paul Workman

Yup, and while you're at it, the two main ground lugs for the bulk of the circuits are attached to one of two bolts at the top of the motor, just under that DIS and MAP stuff. Just to eliminate a host of future 'gremlins' ("while your in there...") it is a good idea to "R&R" the ground connectors with a wire brush or emory cloth and then a coating of dielectric grease or the like to prevent oxidation (now and in the future!).

NOTE: I always suggest that ppl first tie-wrap those wires attached there into respective bundles as they can pull away and be difficult to corral again.

Oops. Forgot to mention those two grounding bolts.

Paul's right.

Don't forget to remove the bolts, clean underneath them and clean the connectors on the ends of the wires.