Car has been great, nothing but maintenance items to date. 85K miles. 3.2 eng, autostick tranny, a typical ES model. A few days ago, the wife was driving to work, and lost the speedo, tach and a/c. Car continued to run, so she continued to work. Drove home, these items came on and off intermittently. I've done some digging since then on google, read about a 'lot' of cars going into limp mode. Ours did not do this, we had all four gears, was able to confirm by using autostick. A *very* few shifts were abrupt, and moving from a stop while going uphill occasionally caused sudden starts, but nothing unsafe or particularly bad about the tranny. Just different behavior.
Took car to local independent shop, but they did not have all the Mopar scanning computers to do thorough diagnosis. They found several codes, but could not pinpoint the problem. They strongly suspected a bad BCM (body control module), but left open the possibility of a communication issue somewhere on the car's bus serving all modules. They told me this meant it could be another module (or more) causing the problem, so they felt better not throwing parts at it. Suggested taking it to dealer for better analysis, which I did.
Dealer did their thing, determined the problem to be in the BCM, and attempted to reprogram it. My impression, based on how they relayed this story to me, was they were a bit surprised to find that just doing this solved the problem. Maybe this is normal and I misinterpreted...They did their test drive and put it back on the scanner, and found everything to be normal. Two hours shop time, no parts. I drove it home last night, made a few stops, about 25 miles total, everything was normal.
This morning, the problem has come back, with new wrinkles. Went out to start it, it runs for a second or two, then shuts off. Does this four/five times in a row. Go inside for a while to deal with unruly children (the wife is at work now, took my car), came back in about an hour. Try starting, it won't fire at all now. All dash lights come on, but no start. On a whim, I put car in neutral, and it starts right up. Not only that, but it stays running. The same problems with no speedo, tach or a/c have come back, but at least I now have a car that runs.
Now at the end of this long story - do I proceed to have the BCM replaced? The obvious answer seems to be yes, but just want to see what others think. Here are the codes from my local shop's diagnosis. Did not get them from the dealer:
P1685 - SKIM invald key P1687 - no MIC bus message P1695 - no body CCD messages P1698 - no CCD messages from TCM
I'm starting to suspect a tranny or TCM problem, maybe instead of or in addition to the BCM. I'm basing this on the infrequent, irregular shifts noted above, the fact that I got the car to start today when I put it in neutral, and the last code shown above. I'm definitely not a Mopar tech or shadetree mechanic, this is just my guess. Another wild thought: could a bad battery be causing any of these problems? I have never replaced it. We bought the car used three years ago, so it's probably the original. Haven't pulled the wheel off to get at it yet. I did read some other threads where the battery was the culprit of some major problems related to control modules. I'm assuming that after all these scans a weak or bad battery would have shown up, but I really don't want to assume anything at this point.
Thanks,
Joe