InvictusDecretum
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While driving at night, I noticed my lights would become bright for half a second or so every once in awhile. I tried to pay extra attention to the voltage gauge, and once saw the needle flick to 30v and then back down to 26v or so. It would do it perhaps once an hour ? Would do it on perfectly flat roads and bumpy.Transmission control unit - these don't like voltage problems. Was your voltage actually high? My truck would go into over-voltage cut-off and on two or three occasions I got an over-voltage warning from my TCU as well. It's the first thing to complain. They are also one of the more problematic modules on these trucks - especially the older trucks. They don't like jump starts and bad/dead batteries or over-voltage conditions. Definitely the first computer item on the list that you should have a spare of. My truck (2008 A1R) already had a new TCU from the previous owner and I keep a spare on hand.
My OVCO adventure:
2008 A1R with 260a charging questions
Currently has a brand new N3221 voltage regulator (2012 vintage I believe - was new in the box with papers). The truck had a 2013 regulator when I picked it up in Houston. It died about 100 miles from Portland - 2600 miles into the trip back. I put in the brand new spare and drove the last 100...www.steelsoldiers.com
Batteries are 2x new Group 24F. Voltage was between 12.6-12.8 on both of them with engine off for ~10hrs.