4L80 DTC 73 Repair

[schaumi]

The transmission control unit of my HMMWV gave the DTC 73 from the beginning.
The resistance measurement of the solenoid valve directly on the plug of the control unit was fine. So I bought a used, supposedly working control unit on ebay.
Unfortunately, this also gave the same DTC.
So I opened the control unit and discovered an obviously discolored Infineon power switch IC.
After replacing the IC, the control unit works again without any problems.
I would like to share this information because I think this is probably a common problem.
The spare part number is "TLE6220 GP".

 

[TOBASH]

Awesome post! I’ve bookmarked it.

 

[Mogman]

The transmission control unit of my HMMWV gave the DTC 73 from the beginning.
The resistance measurement of the solenoid valve directly on the plug of the control unit was fine. So I bought a used, supposedly working control unit on ebay.
Unfortunately, this also gave the same DTC.
So I opened the control unit and discovered an obviously discolored Infineon power switch IC.
After replacing the IC, the control unit works again without any problems.
I would like to share this information because I think this is probably a common problem.
The spare part number is "TLE6220 GP".

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What about the "other" TCM?

 

[schaumi]

What about the "other" TCM?

The repair of the original TCM is on my to-do list for next week.
It has the same discoloration on the same IC and also on the backside of the pcb.

My HMMWV was sold back in 2023 at iron planet without a transmission. Before it was shipped to Austria, a used 4L80 was installed. Therefore, I can only speculate about the actual cause. Maybe a short circuit in the solenoid valve.