Issues after alternator swap

[dunnc1991]

2007 LBZ, ATP tuned, everything else is basically stock. A few days ago, went out to start the truck and it wouldn't start. Had a lot of symptoms of dead batteries. Batteries tested both bad. Replaced them both and noticed the alternator wasn't charging for the first few minutes while driving. Replaced the alternator and belt today. Fired the truck up and it started charging fine, however that's when the problems started. The idle was higher then it was prior to the swap. The idle stuttered a few times then evened out. Took it for a drive and the desired fuel pressure was all over the place and truck was running terrible. Stooped and let it idle for a few minutes and everything cleared up. Took it for a drive again and the converter started to lock in second gear and stayed locked all the way through 6th. The up shifts were delayed as well as the down shifts. The converter would unlock in third gear when downshifting. The truck ran fine prior to changing the alternator. I have to imagine something electrical has happened, but I'm at a loss. I'm going to pull the alternator back out and see if anything is wrong. Codes were P0401, P0540, P0118, P0463, P0673, P0676. Pretty sure all these codes were here prior to the alternator swap. I've searched around but haven't found much as far as my symptoms are. If anyone has any insight I'd greatly appreciate it. Not sure if this is the right place for this, but mods please move as needed.

 

[Mike L.]

Sounds like bad TCM.

 

[jelweldr177]

Well heres one for you to think about,
Blew the lower trans line, pinhole in the rubber hose. Installed new one, after.it had thrown a dozen trans and comms codes thru the edge scanner. Now keep in mind this thing had never seen a code other then low rail pressure once a year for whatever reason. Cleared the codes, max boost 7 lbs., quarter peddle...or acts like limp mode but wld still shift erradic and intermittantly but no power. After new map, maf, vps, fuel peddle, blown fass relay replaced. Same issues. Reflashed to stock, no codes yet, reflashed w original ecm tune by starlite, no go, wldnt take for whatever reason. New tuner, new tunes. Ecm took that one. Had intermittant boost on random hard downshifts after tach hit 2.9k, still no codes, normal 7 lbs of boost, no smoke, ALL gauges looked perfect, rail, trans temp, engine temp, map %. Except the boost. Quarter peddle.
Still no codes, drove it home...something happened every time i turned the steering wheel hard left,,,,, i dont recall exactly which code but it was along the lines of low input voltage group b injector circuit. At any rate, something catastrophic happened to this ecm that id thought now makes me think a harness issue,
someday ill fix it...food for thought.

Sent from my SM-G965U using Tapatalk

 

[dunnc1991]

Thanks for the replies.

Figured I'd update this. Should've dug a little deeper before making my original post. Pulled the alternator back out and found the coolant temp sensor was broken. Checked the other harnesses while I was in there and all was well. Put it all back together and it's good to go. Happy it was an easy fix.

 

[TheBac]

Moved to LBZ section.

Glad you found the problem and it was easy to repair.