4L80E Lockup in Second Gear
Thread Starter
Teching In
Joined: Feb 2011
Posts: 17
Likes: 2
From: Midwest
4L80E Lockup in Second Gear I’ve done a search, but haven’t found anyone else with my exact problem.
Here’s a little background: I have a 2006 4L80E that came out of an Express 3500 School Bus with 100k miles. The forward drum was burned, otherwise everything looked fine. I cleaned and rebuilt it myself with upgraded clutches/steels—except the overdrive drum because I don’t have the tool to do it. I topped it off with a Yank SS4000 stall.
As soon as the car shifts into second gear it goes into lockup, regardless if I’m just cruising or WOT, hot or cold.
For reference I have a Holley Terminator X Max controlling the engine and transmission, and the computer is commanded to lock in 4th gear over 1350rpm just like it did for my old 4L60E. The Holley has the plug for a 4L60E and I bought a conversion harness that goes to the 4L80E.
I put 6AN cooler lines in—first using a regular fitting then switching to banjo fittings because I didn’t clearance the tunnel enough. Both times the rear fitting had the long shank; currently they’re tied into the radiator without an external cooler.
Things I’ve done so far:
-Replaced the TCC solenoid—this didn’t help, although it takes about a second to go into lockup now, instead of almost instantly. I used a “Genuine GM” part.
-Replaced the TCC valve—I bought this TransGo unit https://www.summitracing.com/parts/trg-4l80e-tcc and used the firmer green spring. I checked that all the valves in the valve body moved freely and cleaned it again before re-installing.
Each time I’ve dropped the pan I’ve replaced the fluid with new.
Does anyone have any insight into what could be causing this? I’m wondering if it’s the valve body or possibly the pump? Could it be the converter? The 4L60 to 4L80 harness?
Here’s a little background: I have a 2006 4L80E that came out of an Express 3500 School Bus with 100k miles. The forward drum was burned, otherwise everything looked fine. I cleaned and rebuilt it myself with upgraded clutches/steels—except the overdrive drum because I don’t have the tool to do it. I topped it off with a Yank SS4000 stall.
As soon as the car shifts into second gear it goes into lockup, regardless if I’m just cruising or WOT, hot or cold.
For reference I have a Holley Terminator X Max controlling the engine and transmission, and the computer is commanded to lock in 4th gear over 1350rpm just like it did for my old 4L60E. The Holley has the plug for a 4L60E and I bought a conversion harness that goes to the 4L80E.
I put 6AN cooler lines in—first using a regular fitting then switching to banjo fittings because I didn’t clearance the tunnel enough. Both times the rear fitting had the long shank; currently they’re tied into the radiator without an external cooler.
Things I’ve done so far:
-Replaced the TCC solenoid—this didn’t help, although it takes about a second to go into lockup now, instead of almost instantly. I used a “Genuine GM” part.
-Replaced the TCC valve—I bought this TransGo unit https://www.summitracing.com/parts/trg-4l80e-tcc and used the firmer green spring. I checked that all the valves in the valve body moved freely and cleaned it again before re-installing.
Each time I’ve dropped the pan I’ve replaced the fluid with new.
Does anyone have any insight into what could be causing this? I’m wondering if it’s the valve body or possibly the pump? Could it be the converter? The 4L60 to 4L80 harness?
TECH Junkie
Joined: Dec 2012
Posts: 3,621
Likes: 1,335
From: Iowa
Check your wiring and pinout to the ECU
A simple test would be to unplug the trans and road test .
4l80e unplugged is default 2nd gear...if it does that but is not locked up, then you know you have an electrical issue.
the 4l80e provides TCC apply oil to the solenoid via 2nd gear oil...so when you shift to 2nd, the solenoid is seeing the oil it needs to enable lockup
Since you've replaced the solenoid I suspect it is either bad wiring or programming or a mix causing your issue with the holley
A simple test would be to unplug the trans and road test .
4l80e unplugged is default 2nd gear...if it does that but is not locked up, then you know you have an electrical issue.
the 4l80e provides TCC apply oil to the solenoid via 2nd gear oil...so when you shift to 2nd, the solenoid is seeing the oil it needs to enable lockup
Since you've replaced the solenoid I suspect it is either bad wiring or programming or a mix causing your issue with the holley
Thread Starter
Teching In
Joined: Feb 2011
Posts: 17
Likes: 2
From: Midwest
Check your wiring and pinout to the ECU
A simple test would be to unplug the trans and road test .
4l80e unplugged is default 2nd gear...if it does that but is not locked up, then you know you have an electrical issue.
the 4l80e provides TCC apply oil to the solenoid via 2nd gear oil...so when you shift to 2nd, the solenoid is seeing the oil it needs to enable lockup
Since you've replaced the solenoid I suspect it is either bad wiring or programming or a mix causing your issue with the holley
A simple test would be to unplug the trans and road test .
4l80e unplugged is default 2nd gear...if it does that but is not locked up, then you know you have an electrical issue.
the 4l80e provides TCC apply oil to the solenoid via 2nd gear oil...so when you shift to 2nd, the solenoid is seeing the oil it needs to enable lockup
Since you've replaced the solenoid I suspect it is either bad wiring or programming or a mix causing your issue with the holley
Perfect. This is what I needed, thanks. I completely unplugged the trans harness--speed sensors, too--from the Holley and drove around the parking lot at work. It didn't lock at all and didn't stall the engine when I hit the brakes.
I need to figure out if it's the adapter messing things up or not. Could the plug be 180 degrees off from the Holley harness? When I first did the swap I had the 4L60 off 180 degrees and only had second and fourth gear if I remember correctly. Otherwise my dad thinks it could be the wiring inside the trans.
TECH Junkie
Joined: Dec 2012
Posts: 3,621
Likes: 1,335
From: Iowa
Like I said...lots of possibilities, but you need to look over all wiring from the holley ecu down to the trans, and then also verify the pin mapping and tuneup settings in the ecu
If that all checks out ok then drop the pan and inspect internal wiring, but I don't have a strong suspicion its in the pan...I think it's probably tuneup or external wiring.
If that all checks out ok then drop the pan and inspect internal wiring, but I don't have a strong suspicion its in the pan...I think it's probably tuneup or external wiring.
TECH Enthusiast
Joined: Apr 2023
Posts: 536
Likes: 85
I’ve done a search, but haven’t found anyone else with my exact problem.
Here’s a little background: I have a 2006 4L80E that came out of an Express 3500 School Bus with 100k miles. The forward drum was burned, otherwise everything looked fine. I cleaned and rebuilt it myself with upgraded clutches/steels—except the overdrive drum because I don’t have the tool to do it. I topped it off with a Yank SS4000 stall.
As soon as the car shifts into second gear it goes into lockup, regardless if I’m just cruising or WOT, hot or cold.
For reference I have a Holley Terminator X Max controlling the engine and transmission, and the computer is commanded to lock in 4th gear over 1350rpm just like it did for my old 4L60E. The Holley has the plug for a 4L60E and I bought a conversion harness that goes to the 4L80E.
I put 6AN cooler lines in—first using a regular fitting then switching to banjo fittings because I didn’t clearance the tunnel enough. Both times the rear fitting had the long shank; currently they’re tied into the radiator without an external cooler.
Things I’ve done so far:
-Replaced the TCC solenoid—this didn’t help, although it takes about a second to go into lockup now, instead of almost instantly. I used a “Genuine GM” part.
-Replaced the TCC valve—I bought this TransGo unit https://www.summitracing.com/parts/trg-4l80e-tcc and used the firmer green spring. I checked that all the valves in the valve body moved freely and cleaned it again before re-installing.
Each time I’ve dropped the pan I’ve replaced the fluid with new.
Does anyone have any insight into what could be causing this? I’m wondering if it’s the valve body or possibly the pump? Could it be the converter? The 4L60 to 4L80 harness?
Here’s a little background: I have a 2006 4L80E that came out of an Express 3500 School Bus with 100k miles. The forward drum was burned, otherwise everything looked fine. I cleaned and rebuilt it myself with upgraded clutches/steels—except the overdrive drum because I don’t have the tool to do it. I topped it off with a Yank SS4000 stall.
As soon as the car shifts into second gear it goes into lockup, regardless if I’m just cruising or WOT, hot or cold.
For reference I have a Holley Terminator X Max controlling the engine and transmission, and the computer is commanded to lock in 4th gear over 1350rpm just like it did for my old 4L60E. The Holley has the plug for a 4L60E and I bought a conversion harness that goes to the 4L80E.
I put 6AN cooler lines in—first using a regular fitting then switching to banjo fittings because I didn’t clearance the tunnel enough. Both times the rear fitting had the long shank; currently they’re tied into the radiator without an external cooler.
Things I’ve done so far:
-Replaced the TCC solenoid—this didn’t help, although it takes about a second to go into lockup now, instead of almost instantly. I used a “Genuine GM” part.
-Replaced the TCC valve—I bought this TransGo unit https://www.summitracing.com/parts/trg-4l80e-tcc and used the firmer green spring. I checked that all the valves in the valve body moved freely and cleaned it again before re-installing.
Each time I’ve dropped the pan I’ve replaced the fluid with new.
Does anyone have any insight into what could be causing this? I’m wondering if it’s the valve body or possibly the pump? Could it be the converter? The 4L60 to 4L80 harness?
For me, it was the wrong 4L60E t0 4L80E adapter harness. I bought the PCM of NC adapter cable that has the logic circuit board built into the cable and had a tuner set the PCM exactly how PCM of NC says to set it....and bam......perfect operation, all done.
I have a factory 1998 PCM in my 1998 Trans Am. So thats what fixed my issues. For 4 years before that my 4L80E operated perfect. This all started after I installed a new engine and a tuner downloaded a file that changed a bunch of settings and I bought a new cable adapter that was wrong at first.
