Ok so i put a new motor in my car and it has a CEL. It's an EM1 with a OBD1 p28. I jumpered the service connector and turned the car on and the CEL light stays solid. I tried a different ECU but it still wont show me the code. What does it mean if the CEL light stays solid?

 

since your using on obd1 p28, did you buy an ecu jumper harness? if you did, then some jumper harnesses give an option to place a switch using two wires off of the jumper harness to check the cels, so instead of jumping the service connector u can just flip the switch... if you have instructions as to which wires these are, i would try jumping them first.

btw, you don't need to turn the car on, just flip the ignition switch to the "on" position.

 

same issue here... same hardware obd1 p28, dark green plugs (2 pin and one 3 pin)...no one mentions the 3pin...is this part of a "ecu jumper harness" TwoKSiR mentions?

RE: solid CEL light. same issue here - 2pin plug is jumped with a paperclip. Search reveals may be related to bad ECU but no definitive answer? or perhaps reminiscent of ECU being in Safe Mode.

What is SAFE MODE and how is it triggered? - related to solid CEL light?
- 94 Si hatch

frank_el_tanke did you ever resolve your issue, what was it?