6l80e PO741 Code Help!
Thread Starter
Joined: Dec 2009
Posts: 2,331
Likes: 29
From: Glennville, GA.
6l80e PO741 Code Help! I have 2 6l80e i have built back to back. 2 seperate vehicles. They both shift great no issues there. But they both are showing the P0741 codes and are getting pretty hot within a short test drive. over 200* area. i have tried everythin to figure this out.
1st vehicle we fully rebuilt had this issue. We repulled trans and replaced with another converter. Original techum still being used. No luck with fix.
2nd vehicle same build out with a new pump. everything new same code. No techum was replaced on this one either.
Is this a sign tht we might need to try installing a new techum on both of these? Techum are pricey and i still have the 2nd vehicle at the shop currently. Other than the codes and the hot trans temp they both shift great without any hiccups. I have researched the crap out of this code fix without any hard evidence. Its also strange tht 2 vehicle back to back experience same codes and symptoms. I have rebuilt alot of these over the yrs and they can be some funny trannies with the electrical aspect. We rarely have to swap a new techum on them. I also do all the transgo/sonnax fix valves for the pump and valvebody issues.
Last thing the 2nd vehicle 13 tahoe shows the code as permenant and will not clear out. even with a write entire over the ecu and trans it still shows on start up. The 1st vehicle 17 Silverado would clear out and pop up after a few key cycles. Any ideas?
1st vehicle we fully rebuilt had this issue. We repulled trans and replaced with another converter. Original techum still being used. No luck with fix.
2nd vehicle same build out with a new pump. everything new same code. No techum was replaced on this one either.
Is this a sign tht we might need to try installing a new techum on both of these? Techum are pricey and i still have the 2nd vehicle at the shop currently. Other than the codes and the hot trans temp they both shift great without any hiccups. I have researched the crap out of this code fix without any hard evidence. Its also strange tht 2 vehicle back to back experience same codes and symptoms. I have rebuilt alot of these over the yrs and they can be some funny trannies with the electrical aspect. We rarely have to swap a new techum on them. I also do all the transgo/sonnax fix valves for the pump and valvebody issues.
Last thing the 2nd vehicle 13 tahoe shows the code as permenant and will not clear out. even with a write entire over the ecu and trans it still shows on start up. The 1st vehicle 17 Silverado would clear out and pop up after a few key cycles. Any ideas?
TECH Junkie
Joined: May 2012
Posts: 3,052
Likes: 716
From: Poplarville, MS
My understanding of permanent codes is that the ecm will clear the code once the ecm has run its test for that code and it has passed. Sorry for the incorrect terminology. I don't think this is not your problem, but have you bypassed the cooler thermostat?
Thread Starter
Joined: Dec 2009
Posts: 2,331
Likes: 29
From: Glennville, GA.
Yes I bypass the thermostat on all models able to. I did some more research tonight and looked over sonnax zip kit instructions. They take about the TCC valve in the pump stator half being bad causing the p0741 code. Also the TCC valve in the valvebody can cause it. I always use the transgo TCC select valves with has the valve tht fixes the valve body part.
I think it's in the pump area. I do remember the 13 trans having a sonnax PR valve tht was a lil trashed. I just tossed it and put a new transgo PR valve in its place. But I didn't think about sonnax using the drill and check ball method with there valve. I don't use them often. Anyways maybe thts an issue?
Non the less imma just put another complete pump setup on this unit and see what's happens.
I think it's in the pump area. I do remember the 13 trans having a sonnax PR valve tht was a lil trashed. I just tossed it and put a new transgo PR valve in its place. But I didn't think about sonnax using the drill and check ball method with there valve. I don't use them often. Anyways maybe thts an issue?
Non the less imma just put another complete pump setup on this unit and see what's happens.
The TCM will try twice to lock up when commanded then if it doesn't see it lock 741 sets.
It's redundant but I would clear codes verify then see what the TCC slip speed does when it tries to lock.
The running hot is inline with the TCC not locking.
Since it's a rebuild it's hard to say where the problem may lie this is one of those I would say to pull it out take it apart and go over each item step by step and verify everything is right. 2 trannys with the same problem points to more than likely a mistake maybe in the same area of overhaul on each.
It's redundant but I would clear codes verify then see what the TCC slip speed does when it tries to lock.
The running hot is inline with the TCC not locking.
Since it's a rebuild it's hard to say where the problem may lie this is one of those I would say to pull it out take it apart and go over each item step by step and verify everything is right. 2 trannys with the same problem points to more than likely a mistake maybe in the same area of overhaul on each.
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Verdad Gallardo TECH Junkie
Joined: May 2012
Posts: 3,052
Likes: 716
From: Poplarville, MS
TCMS are very sensitive if it was electrical it would have a code specifically for the solenoid. If I were a bettin man you'll find the problem in a hydraulic circuit.
Thread Starter
Joined: Dec 2009
Posts: 2,331
Likes: 29
From: Glennville, GA.
Update problem fixed on this one. Bad torque converter. Trashed the techum solenoid screen and was most likely causing some issues as well. All clutch packs looked good. Valves on valve body checked good. Pump checked out good. New converter works great holding good temps and no more code so far.