Long story short...I had TRAC OFF and Check engine lights coming on and Auto Zone pulled code P0122 (TPS). Went to shop and had new TPS put on, and car broke down the same day. Went back in the shop and they diagnosed short to ground, traced to wiring harness and found bad wire at junction box along firewall under brake booster. They fixed it and it ran fine for 4 days until the alternator failed. Could they have caused my alternator to fail by not properly fixing the wire? Also, could my wire have shorted out due to them not properly fixing/diagnosing TPS issue? They're also severly overchargin me or the wiring work ($450) and for the alternator work ($526)!
TP sensor short fixed but now I have a failed alternator on 2003 Chevrolet Cavalier
by aprilmiller_81 in South Bend, IN on August 27, 2009
ANSWER by Bret Bodas on August 27, 2009
Without seeing it first hand it's hard to know if there is a possible relation, but it seems unlikely since they are two different circuits and it would be hard to believe any kind of failure of the TPS circuit could do any damage to the Alternator. You may consider having another shop look at this if you don't feel good about the shop that is diagnosing the problem.