Author Topic: Cannot retrieve SES (service engine soon) codes  (Read 2436 times)

Offline 1979C20

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Cannot retrieve SES (service engine soon) codes
« on: July 22, 2012, 12:26:25 AM »
I have another thread open troubleshooting an 89 suburban here,  http://forum.73-87chevytrucks.com/smforum/index.php/topic,24190.0.html

But, I'm looking for a more specific answer. What does it mean when you have a check engine light and neither a code reader or A and B terminal jumper will give you a code? The obd1&2 code reader rented from oreilly acted as if it wasnt pligged in. and when we jumped terminal a and b, key on engine off, the check engine light stays solid. What would be the causes of the exm not communicating with the aldl? When the trucm first gave him problems he was able to pull a coolant temp sensor code using the jumper trick. He replaced that, the map, iac, tps, and 02 sensor(s) are all new. And after he replaced the coolant temp the truck sat for a bit and now no communication to the ALDL. Weve traced the wires and cant find any obvious issues with them.
1979 SCLB C20 Q-jet 350 SM465 14b F.F. 4.10 G80
1989 GMC Suburban V2500 TBI350 TH400 4in lift 35's 14b SF

Offline 78 Chevyrado

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Re: Cannot retrieve SES (service engine soon) codes
« Reply #1 on: July 23, 2012, 01:09:54 AM »
I'd say since the jumper didn't work, there's a bad connection in the wiring or at the computer hookup.
Kenny

1978 C-20, 350/400, 3.73, Graystone Metallic, Raceline Renegade 8 Wheels - 18x8.5, 275/70R18 BFG KO's