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MEW MEW 10/8/2021

2005 Chevrolet Express 3500 Base 8 Cyl 6.00L

Transmissions & Drivetrains

Where is the TCM located? If any?

Hello! The issue is when I drive the van past the 3 gear it doesn't switch to the 4th.
The diagnostic reads as follows: shift solenid B,
shift solenoid A
torque converter clutch pressure control.
But all issues above has been replaced. All cables/harness. And it still reads the same.
Which led me to believe it was the TCM.
Thank you so much in advance!

1 Answer


Jimm 10/9/2021

The TCM is located on right front inner fender above the wheel well.

Some common signs of a bad transmission control module include:
Unpredictable shifting.
Trouble shifting into higher gear.
Trouble downshifting.
Getting stuck in the same gear.
Poor fuel economy.
Check engine light comes on.

It has been found that the transmission control module (TCM) is possibly being shorted to battery voltage during vehicle diagnosis and/or repairs.

This applies to a host of GM vehicles, including the following equipped with 4T40-E or 4T45-E or 4L60-E automatic transmission:

According to GM, if the positive battery jump start post/terminal cover is removed and/or missing, and the TCM comes into contact with the positive battery jump start post/terminal during diagnosis and/or service, the TCM will be damaged and must be replaced.

Prior to removing the TCM from its mounting bracket, disconnect the negative battery cable. If service requires the negative battery cable to be installed for diagnostic purposes, unplug the TCM before it is removed from its mounting bracket. Unplugging the TCM will eliminate the possibility of damage.

NOTE: Control module damage may result when the metal case contacts battery voltage. DO NOT contact the control module metal case with battery voltage when servicing a control module, using battery booster cables or when charging the vehicle battery. DO NOT use the TCM or its mounting bracket/fasteners as the ground connection when jump starting.


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