Well, I had to do an alternator change on my 2000 saturn ls2..
Without a working alternator, and a fully charged car battery (by charger) I drove 2 miles or so to a place where I could work on it. I should mention that the car lost almost all power and shifting capabilities right before I got there. (battery was garbage) Now I get a code saying that I have no comms with the TCM to the ECM even with my new alternator in and I think my car is stuck in limp mode.. I tried an ECM reset, B+ fuse pull and I'm about to change the tranny fluid filter.. But I doubt the filter is to blame... And the shifting problems are slightly intermittant but 80% limp mode. Could it be the weak, half-bum battery? I put a slightly better battery in and got 3rd gear, an improvement from stock battery only giving me second gear...but still no overdrive.. If all suggestions fail, where is this TCM? Codes are p1511 and u2106. Thanks a ton
My car has 200000 miles.
My car has an automatic transmission.
The TCM is in the right rear of engine compartment. The first thing to check after putting in a new good battery and checking the charging system is to see if any fuses are blown for the TCM. The engine is in a failure mode and may need to have codes cleared after checking fuses. If problem with TCM continues then you will need to have it checked for power to module and may need new TCM.
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