So a while back my dad (who was helping me do a timing belt change) put the battery in with reverse polarity and it killed the BCM. Well i bought a junker bcm off the internet in hopes that I wouldn't need a reprogramming. One of the things I was worried about was the variety of different part numbers Chrysler has out for what seems to be the same part. I can put some at ease by saying the part number of the BCM i pulled off ended in 38 and the one I put on ended in 37. And apart from one thing (maybe) it works perfectly (with no program).

Some things to note:
-Replacement unit was off of a 2006 (same year) V6 (different) Sport (same). All cabin features are the same and all cabin features now work again (radio, lights, chime, keyless entry, rear hatch etc.)
- I had the impression that the body control module controlled ONLY these types of things but the Liberty has its quirks. The oil pressure sensor and possibly the water in fuel sensor are both effected in some way by this module (OPS was confirmed through service manual diagnostics).
- As soon as I replaced my BCM i got a WIF and OP light (that did not go away after erasing with OBDII tool). The WIF was simply because I had replaced my fuel filter head and hadn't bothered to plug it back in (it went away the moment I did that).

I speculate that the BCM is still programmed for the gasser and is looking for a phantom pressure from its old (now scrapped) V6 liberty. I'm not sure on the oil pressure difference between the two engines but I assume they'd be different enough to confuse the BCM. It could also be that the cheapo OPS is out or I've lost continuity but I'm currently too lazy to crawl under with the dmm and start diagnosing.

Any ideas or speculations? Why would the BCM have anything to do with these sensors?

Hope I helped anyone else in such off an unfortunate circumstances. I'm also glad to have a radio, door locks and cabin lights back finally.

. Another interesting development is that I'm in part time 4x4 according to my lights

I started having the hard shift from 2-3...

This is because the switch on the transfer case that controls the indicator light has either gone bad or has fallen out of sync.


This seems to be a common problem with the 545rfe in the CRD. I dont know what the solution is but its not related to the BCM. It might clear up on its own.

I thought the Oil pressure sensor on the CRD sent out either a yes or a no(as in "yes your engine is about to blow up", or "no your engine is not about to blow up"), not an actual pressure reading.

This is because the switch on the transfer case that controls the indicator light has either gone bad or has fallen out of sync.


This seems to be a common problem with the 545rfe in the CRD. I dont know what the solution is but its not related to the BCM. It might clear up on its own.