Can anyone help with this 4l60e problem?
Thread Starter
Staging Lane
Joined: Dec 2016
Posts: 62
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Can anyone help with this 4l60e problem? I have searched this forum and others with no success so I hope someone will know the answer to this issue.
I have a 2001 ls1 engine swap hooked to a 4l60e trans. It upshifts and downshifts correctly but every so often it will not go into passing gear. I can not find any pattern as to when it will happen. It can be cold or hot, day or night, raining or dry. it might happen once a day or once a block. It doesn't matter if it is in O/D or 3rd gear. It will downshift manually. The engine is stock except for a GM "hot cam". The trans was rebuilt this year. The electrical harness is brand new from Painless wiring. I have 5v at the TPS. I have tried 3 different TPS's and throttle bodies. I have checked all the wiring for damage and all the connectors and plugs for a secure fit. I understand that the ECM controls the trans completely. The ECM was reflashed from a manual to a automatic. There have never been any codes show up from the trans. I get code P0121 pop up pretty much daily but can not find any reason for it. The trans will have the problem with or without the code. The code will go away on its own without erasing it from a scanner. The scanner i have (harbor freight)only seems to show tps percentage not voltage. This has been an ongoing problem for me. I have been to several shops in town as well as the Chevy dealer and no one seems to know why or has heard of this happening. Can anyone help?
I have a 2001 ls1 engine swap hooked to a 4l60e trans. It upshifts and downshifts correctly but every so often it will not go into passing gear. I can not find any pattern as to when it will happen. It can be cold or hot, day or night, raining or dry. it might happen once a day or once a block. It doesn't matter if it is in O/D or 3rd gear. It will downshift manually. The engine is stock except for a GM "hot cam". The trans was rebuilt this year. The electrical harness is brand new from Painless wiring. I have 5v at the TPS. I have tried 3 different TPS's and throttle bodies. I have checked all the wiring for damage and all the connectors and plugs for a secure fit. I understand that the ECM controls the trans completely. The ECM was reflashed from a manual to a automatic. There have never been any codes show up from the trans. I get code P0121 pop up pretty much daily but can not find any reason for it. The trans will have the problem with or without the code. The code will go away on its own without erasing it from a scanner. The scanner i have (harbor freight)only seems to show tps percentage not voltage. This has been an ongoing problem for me. I have been to several shops in town as well as the Chevy dealer and no one seems to know why or has heard of this happening. Can anyone help?
TECH Apprentice
Joined: Dec 2014
Posts: 302
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From: Pa
TECH Fanatic
Joined: Jan 2015
Posts: 1,114
Likes: 33
From: Fort Worth, Texas
The PCM will no longer run tests for P0121, Your camshaft profile has changed the vacuum signal to the MAP sensor to the point "Sanity/Performance" checks of the TPS angle vs Manifold Pressure are no longer accurate.
