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Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go hereXJ (84-01)
All OEM related XJ specific tech. Examples, no start, general maintenance or anything that's stock.
Does anyone know the difference between the two PCMs in the title?
My PCM fried from short on the O2 to the exhaust mani. Need to order a new computer but I don’t know which one, the PCM I have is a reman and was spray painted by them, stickers aren’t visible.
Last edited by fitrider82; 04-03-2022 at 11:40 AM.
I think 56041488AF is for Federal emissions, and 56041490AF European emissions. No clue what the difference would be, maybe slightly different tune? Most places can take your VIN number and verify what you need and program the SBEC/PCM to match. Before replacing the PCM, have you verified that the O2 heater fuse and relays were good?
Thanks for the reply, fuse 11 on the ASD circuit is continually popping with the ASD relay insert. I did extensive troubleshooting on every sensor for continuity and narrowed it down to the O2 frying the board.
Originally Posted by lawsoncl
I think 56041488AF is for Federal emissions, and 56041490AF European emissions. No clue what the difference would be, maybe slightly different tune? Most places can take your VIN number and verify what you need and program the SBEC/PCM to match. Before replacing the PCM, have you verified that the O2 heater fuse and relays were good?
Fuse 11 for the PCM, ASD relay, trans computer, right. What's confusing to me is that it only pops when the ASD relay is in, which implies that it's not the PCM popping it, but something fed from the ASD circuit? Does it still do it if you pull fuse 24 under the hood for the O2 heaters? I wonder if melted wiring insulation further upstream somewhere and you have a short to ground hiding somewhere in the wiring harness.
I'm skeptical that even shorting 12 volts to the O2 sensor input to the ECM would damage it.
It pops after any combination of removing relays/fuses if the ASD relay is plugged in. We tested every sensor on that circuit, I unplugged the whole harness from C107 toward the driver side, unwrapped the loom and inspected every cable. The only short was the Upstream O2 that was missing 50% of the copper on one of the wires (not sure which one), I fixed it and it’s still popping. Did a ton of troubleshooting/isolating to narrow it down to the computer. Checked downstream O2, fuel pump, tested for resistance and voltage, everything checked out with every sensor. PCM is the only thing left and it’s a reman that I have no idea is how old, I tried opening it to find anything out of the ordinary but that sucker is sealed tight.
Originally Posted by lawsoncl
Fuse 11 for the PCM, ASD relay, trans computer, right. What's confusing to me is that it only pops when the ASD relay is in, which implies that it's not the PCM popping it, but something fed from the ASD circuit? Does it still do it if you pull fuse 24 under the hood for the O2 heaters? I wonder if melted wiring insulation further upstream somewhere and you have a short to ground hiding somewhere in the wiring harness.
I'm skeptical that even shorting 12 volts to the O2 sensor input to the ECM would damage it.
04-03-2022, 10:43 AM
PCMs 56041488AF vs 56041490AF???
