4L80E Trans light, power supply?

[justHelpChris]

Hello,

i just started to repair my HMMWV.

i have the problem that the trans light is always on,
i checked with the multimeter

#657 with masterswitch is off, there are 4.7V

the Relay is working correct, 12V on run, 0 at off

i also have always 5V at the TPS sensor, even when the engine is off, normal?

if i disconnect the TCM (J1), than i have not the problem

so,

could be the problem that it is the wrong TCM??
i have the 6.5liter turbo

tcm with eprom

i hope somebody can help.

greetings from Austria

 

[Mogman]

You need to check 290C/291C (connected to trans relay) to make sure the trans relay is releasing when run switch is off.

 

[justHelpChris]

as mentioned above the relay release correct!

without tcm,
i have alle the 12V when turned on at 290/291/810/657
and 0V when turned off

when i connect the J1 from TCM
i have 12V when turned on
and 4.7 when turned off at 290/291/810/657

does the TPS always have 5V even when Turned off?

 

[Mogman]

By the way, Welcome to the SS forums!
I do not believe you should have 5V at the TPS when off, it looks like you have a defective TCM.
It seems you have done a thorough job of troubleshooting the issue.
All HMMWV TCMs are basically interchangeable only the shift points are a little different between the turbo and NA engines.