P0740 and P0785 - 80e swap and verter
07-02-2017, 12:38 PM
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P0740 and P0785 - 80e swap and verter
This is my brother in laws truck 180 miles from me. I did the wiring modification to the stock trans connector and added the 2nd vss.
I have stock 4l80e tune settings in it, I know there will be some shifting issues under WOT, but I need to be able to drive it before I worry about proper WOT shifts
If commanded through HP tuners I have gears 1-4 and solid lock up on the verter. I can force it to down shift through VCM controls, but even when it says it is in 1st in the scanner, it sure feels like it is still in 2nd (codes come up fast, guessing it is already in limp mode at that point).
If I let the truck shift on it's own (assuming I have cleared the codes), it starts in 1st, will shift to 2nd fine, has even shifted to 3rd on its own. It quickly throws both P0740 and P0785 and will not down shift even when coming to a stop, it will stay in what ever gear it was last in. Assuming it is now in limp mode due to the codes and wont do anything. I can however command a down shift but here again, logger shows 1st but feels like a 2nd start.
4l80e is a fresh rebuild done by a friend of mine that is a GM trans tech for 20 years, I trust his work. Converter is a new Road Runner advertised as a 2,800-3,200.
Any and all thoughts are welcome as I am not sure where to start.
I have stock 4l80e tune settings in it, I know there will be some shifting issues under WOT, but I need to be able to drive it before I worry about proper WOT shifts
If commanded through HP tuners I have gears 1-4 and solid lock up on the verter. I can force it to down shift through VCM controls, but even when it says it is in 1st in the scanner, it sure feels like it is still in 2nd (codes come up fast, guessing it is already in limp mode at that point).
If I let the truck shift on it's own (assuming I have cleared the codes), it starts in 1st, will shift to 2nd fine, has even shifted to 3rd on its own. It quickly throws both P0740 and P0785 and will not down shift even when coming to a stop, it will stay in what ever gear it was last in. Assuming it is now in limp mode due to the codes and wont do anything. I can however command a down shift but here again, logger shows 1st but feels like a 2nd start.
4l80e is a fresh rebuild done by a friend of mine that is a GM trans tech for 20 years, I trust his work. Converter is a new Road Runner advertised as a 2,800-3,200.
Any and all thoughts are welcome as I am not sure where to start.
07-02-2017, 01:48 PM
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Just talk to my trans builder buddy. He suggested I check ground to both PCM and PCM to trans.
All PCM grounds come in at 0.4ohm
PCM to Pin D light Blue comes in at 0.5 - 0.6ohm
All PCM grounds come in at 0.4ohm
PCM to Pin D light Blue comes in at 0.5 - 0.6ohm