4L80E Swap now no reverse
Thread Starter
Teching In
Joined: Feb 2008
Posts: 26
Likes: 1
From: Lorena, TX
4L80E Swap now no reverse I swapped 4L80e into my 2008 Silverado. Transmission was built by local transmission guy, with the usual mods and good parts.
I'm now running an ICT adapter harness for the 4L70e swap and have a new email tune loaded on ECM and TCM.
I can't to get reverse to engage, and speedo reads 50 or more mph when I rev it up in park. Also, HP Tuners log temp reads -40, and gear commanded says 2, no matter where the shifter is.
I ordered and tried out an ebay "4l80e TCM", made no difference.
I have verified the pin outs on the connectors several times, and it's all back to stock layout, with the adapter harness.
I have HP Tuners, and a pressure gauge, but I'm not sure what kind of readings I should have, or how to check to see if it's an electrical problem, or something else.
I would appreciate any guidance on where to look.
Thanks in advance,
Jeff
I'm now running an ICT adapter harness for the 4L70e swap and have a new email tune loaded on ECM and TCM.
I can't to get reverse to engage, and speedo reads 50 or more mph when I rev it up in park. Also, HP Tuners log temp reads -40, and gear commanded says 2, no matter where the shifter is.
I ordered and tried out an ebay "4l80e TCM", made no difference.
I have verified the pin outs on the connectors several times, and it's all back to stock layout, with the adapter harness.
I have HP Tuners, and a pressure gauge, but I'm not sure what kind of readings I should have, or how to check to see if it's an electrical problem, or something else.
I would appreciate any guidance on where to look.
Thanks in advance,
Jeff
Reverse is hydraulic on a 4L80E. No electrical input required. If you don't have reverse there's a mechanical problem.
Check dipstick calibration, check fluid level, check shifter adjustment, check line pressure. In that order.
Check dipstick calibration, check fluid level, check shifter adjustment, check line pressure. In that order.
Thread Starter
Teching In
Joined: Feb 2008
Posts: 26
Likes: 1
From: Lorena, TX
Builder marked dipstick to pan gasket level, and I added 1 qt "just make sure".
Linkage is good, tried that, too.
Pressure is steady idling at 120 psi, until I put it into gear, then it jumps up, is kind of erratic, then settles back down to 120 or so.
What psi should I be seeing?
Linkage is good, tried that, too.
Pressure is steady idling at 120 psi, until I put it into gear, then it jumps up, is kind of erratic, then settles back down to 120 or so.
What psi should I be seeing?
TECH Junkie
Joined: May 2012
Posts: 3,050
Likes: 716
From: Poplarville, MS
I swapped 4L80e into my 2008 Silverado. Transmission was built by local transmission guy, with the usual mods and good parts.
I'm now running an ICT adapter harness for the 4L70e swap and have a new email tune loaded on ECM and TCM.
I can't to get reverse to engage, and speedo reads 50 or more mph when I rev it up in park. Also, HP Tuners log temp reads -40, and gear commanded says 2, no matter where the shifter is.
I ordered and tried out an ebay "4l80e TCM", made no difference.
I have verified the pin outs on the connectors several times, and it's all back to stock layout, with the adapter harness.
I have HP Tuners, and a pressure gauge, but I'm not sure what kind of readings I should have, or how to check to see if it's an electrical problem, or something else.
I would appreciate any guidance on where to look.
Thanks in advance,
Jeff
I'm now running an ICT adapter harness for the 4L70e swap and have a new email tune loaded on ECM and TCM.
I can't to get reverse to engage, and speedo reads 50 or more mph when I rev it up in park. Also, HP Tuners log temp reads -40, and gear commanded says 2, no matter where the shifter is.
I ordered and tried out an ebay "4l80e TCM", made no difference.
I have verified the pin outs on the connectors several times, and it's all back to stock layout, with the adapter harness.
I have HP Tuners, and a pressure gauge, but I'm not sure what kind of readings I should have, or how to check to see if it's an electrical problem, or something else.
I would appreciate any guidance on where to look.
Thanks in advance,
Jeff
Thread Starter
Teching In
Joined: Feb 2008
Posts: 26
Likes: 1
From: Lorena, TX
Thanks for your reply.
Nope, the wheels are not moving. That's what's confusing about the speedo.
I have re-pinned this thing a few times, trying different locations, and I finally caved and bought the adapter harness for the gen 4 4L70e to 4L80e from ICT.
I have only moved 4 pins total, and I am 99.99% sure they are back in the stock location.
I am planning to check all the pins on the harness tomorrow and make sure none have backed out, then drop the pan.
Thanks.
Nope, the wheels are not moving. That's what's confusing about the speedo.
I have re-pinned this thing a few times, trying different locations, and I finally caved and bought the adapter harness for the gen 4 4L70e to 4L80e from ICT.
I have only moved 4 pins total, and I am 99.99% sure they are back in the stock location.
I am planning to check all the pins on the harness tomorrow and make sure none have backed out, then drop the pan.
Thanks.
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TECH Junkie
Joined: Dec 2012
Posts: 3,615
Likes: 1,327
From: Iowa
as stated
reverse requires no electronics
And the harness adapter will have nothing to do with a speedometer
the speed going up in park likely means you have the output speed sensor plugged into the input speed sensor
If this is a fresh build...why are you dropping the pan?
Either take it back to the builder, in the truck, or pull it and take it back.
reverse requires no electronics
And the harness adapter will have nothing to do with a speedometer
the speed going up in park likely means you have the output speed sensor plugged into the input speed sensor
If this is a fresh build...why are you dropping the pan?
Either take it back to the builder, in the truck, or pull it and take it back.
Thread Starter
Teching In
Joined: Feb 2008
Posts: 26
Likes: 1
From: Lorena, TX
as stated
reverse requires no electronics
And the harness adapter will have nothing to do with a speedometer
the speed going up in park likely means you have the output speed sensor plugged into the input speed sensor
If this is a fresh build...why are you dropping the pan?
Either take it back to the builder, in the truck, or pull it and take it back.
reverse requires no electronics
And the harness adapter will have nothing to do with a speedometer
the speed going up in park likely means you have the output speed sensor plugged into the input speed sensor
If this is a fresh build...why are you dropping the pan?
Either take it back to the builder, in the truck, or pull it and take it back.
Thanks for your response, I certainly appreciate the information provided, and appreciate your time spent reaching out to help us all.
I understand the reverse issue is going to be a mechanical issue. I was just hoping for something simpler.
I spoke with the builder today, and he's looking back at his build notes, and we'll talk tomorrow, to see how to proceed.
I'm still working on the electrical issues, and will be sending a log to my Tuner, tomorrow, to see if he can tell anything from it.
I have tried reloading the tune into both of TCM's I have, and there's no difference that I can tell. One is the original 4L70e from my truck, and the second is an ebay 4L80e unit.
I believe I have the sensors plugged in to the right plugs on the harnesses, so something must be crossed up elsewhere.
The info I have says the truck harness plugs into the rear sensor, and the plug from the adapter harness plugs into the front.
When I disconnect the front sensor, the speedo stops moving.
I called ICT and they are sending a second adapter harness, just in case there's a problem in the first one.
Any suggestions are welcome.
Thanks,
Jeff
TECH Junkie
Joined: May 2012
Posts: 3,050
Likes: 716
From: Poplarville, MS
The speedometer does not operate off of the front speed sensor. By unplugging that sensor and the speedometer stops working tells you it is not hooked up correctly. I would try swapping the two speed sensor plugs.
Thread Starter
Teching In
Joined: Feb 2008
Posts: 26
Likes: 1
From: Lorena, TX
Swapping the plugs didn't work either, so somehow the signal from the front sensor is getting crossed over onto the speedo circuit.
Next, I'll trace the wiring harness back to the ECM and TCM looking for issues there.