Ok... So lets get some back story. Jeep started stalling. Tried everything under the sun. No bueno. The Jeep has an AX15 Swap from a 94. The previous owner also switched the ECU to the 94 he got when he took apart the 94 donor. Ran fine for me for a bit. After a laundry list of troubleshooting I think I finally figured out the stalling with a new TPS. However.... during my troubleshooting and because he also gave me the original 92' ECU I swapped that back in. When I put it back in the jeep stopped immediately stalling and would now idle forever and would only stall after a bit of driving. The caveat is.. when I installed it my GEN light was on. Swapped back on the 94 ECU.. no GEN light.. so im thinking OK this 94 ECU is trash... Jeep runs worse and no GEN light, what else could be wrong with it. Swap back in the 92. Ring things out and Alternator 14.4 while running, charging the battery, holds strong while driving. Battery, holds a charge for days at a time without running the jeep. All wires "appear" to be in good order.

So what could it be?!?!?!

missing a wire short?

could the Alt or Bat still be bad even though working correctly?

Ignition? It starts fine. I know its the mid point and GEN light trigger... is there a way to check both sides of it to determine if ECU or Alt/Bat?

is there something else in that system tied to the GEN light?

Thanks for the read! JEEP ON!

 

91-95 ECMs should be interchangeable, although if the 1992 ECM was for an automatic you might get a check engine light if it can't see the trans computer.

 

Na it is manual, original to the vehicle. He swapped transmissions just to have the external slave. The 94 PCM was working just fine. Til it wasn't. So I put back on the original 92 PCU. Which let's the jeep run better BUT has the GEN light on, where the 94 did not. Now are you saying that the Trans computer is tied to the "GEN" light or did you think I might have met CEL? Cause I ment GEN. I'm trying to determine if my 92 ECM is bad or is there something I am missing in the ECU/ALT/BAT circuit. I'll do some research on the transmission computer being tied to the GEN light. Thanks.

 

No relationship to the trans computer, just mentioning that might cause a CEL light if you swapped between auto/manual. I knew you meant GEN light, as you were talking about it charging properly. Near as I can tell from the rather sparse wiring diagram I have, the GEN light is controlled by the ECM.

 

Yeah for sure. Think I may just tear the whole wire harness apart from the alt to the battery, under the battery to the TCM and possibly to the ignition and ecu.... before I buy another ECU just to see if the one I have is bad. Will be bit of a task haha