I have another thread open troubleshooting an 89 suburban here,
http://forum.73-87chevytrucks.com/smforum/index.php/topic,24190.0.htmlBut, 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.