another FAILSAFE issue

[e30mpower]

OK, I have ~81k on my 2003 3.0i, I was on the way to my friend's house tonight and as I was pulling up to a stoplight behind a slow-moving Grand Cherokee, I felt a very slight clunk, the rev counter dipped for a second, and transmission failsafe came on. I still had all my gears, so I'm not sure what the problem was.

Went and parked it, turned it off and back on, no problems. Drove for a little while at moderate speeds, pulled into a parking spot at Target, and trans. failsafe came BACK on. Reverse was still working. I drove around the lot, pulled into another spot, shut off the ignition, turned it back on, and now "Service Engine Soon" was lit up, and I was still in transmission failsafe. I let it cool off for about an hour, started it back up, transmission failsafe is gone, but my SES light is still on.

I'm taking it in to get diagnosed tomorrow - but I was hoping someone could ease my anxiety. Failsafe seems to only appear when I'm coming to a stop. Could this be something simpler than needing a new transmission?

[Hit Redline]

Battery? How old is the one you have now? If its the OG battery it might be that under load your alternator is giving good voltage compensating for a weak or dying battery. May not be the issue but I am trying to give you some hope that it might be some thing simple.

I know that when my battery drained and I jumped it, it went into trans fail safe mode as I started to drive and stayed until I replaced the battery.

GL

[Nik]

Should I replace my Batt? or recharge it? they told me that It's good and it can be recharged... It probably died because it was in a ship for a month...

[e30mpower]

My battery is about a year old. I got in the car today and everything was fine. No SES or failsafe. I'm going to take it in tomorrow to see what the codes were. I thought once SES was on, it didn't go off until the codes were cleared. Am I wrong?

[papasmurf]

Originally Posted by e30mpower

My battery is about a year old. I got in the car today and everything was fine. No SES or failsafe. I'm going to take it in tomorrow to see what the codes were. I thought once SES was on, it didn't go off until the codes were cleared. Am I wrong?

No, it can go off after a drive cycle, but the codes are stored until they are cleared.

[e30mpower]

Ok, so I took it in for diagnosis and the failsafe has been traced back to a "momentary loss of power on the CAN bus." That was the only code showing on the transmission. The tech traced it back to the ABS/DSC computer and said that it may need to be replaced, but not until I have some play money. It's in the early stages of failure and he said my DSC may switch on and off by itself in the near future but that was about it, not to worry about trans. failsafe appearing because it was just a side effect of the DSC. I'm resting easy now. :-)