Transmission Light On When Engine Off

[Kevin Donahue]

As the title says, my transmission light is on only when the key is in and engine not running. I just hooked it up finally so I don't really know if this is normal or not.
Once I start the engine it immediately goes off.

Tranny seems to run smooth but every once in a while it doesn't want to go into overdrive for some reason. Once I pull over and key off/back on it seems to fix that. This has happened maybe 3 times in 3500 miles so idk if I should be worried.

Also, is it safe to disconnect the TCM without disconnecting the negative terminal of the battery or do you risk causing damage? Asking for errr.... reasons.

Thanks for your help.

 

[Coug]

Always disconnect the battery before doing ANYTHING.
It might not fry it by having the battery hooked up, but then again it might. It's just much safer overall. Also a very good habit to get into anyway (or just install a battery disconnect switch on the ground anyway)

 

[Kevin Donahue]

Always disconnect the battery before doing ANYTHING.
It might not fry it by having the battery hooked up, but then again it might. It's just much safer overall. Also a very good habit to get into anyway (or just install a battery disconnect switch on the ground anyway)

Yep, I need to get around to doing that... probably not a bad way to keep it from getting stolen either if its a bit hidden.

 

[Coug]

Yep, I need to get around to doing that... probably not a bad way to keep it from getting stolen either if its a bit hidden.

or you can do a keyed battery disconnect, they tend to use a universal key but not many people carry forklift keys with them.

 

[Bulldogger]

hrbergeron had similar troubles recently on one of his HMMWVs. Maybe his thread will help: https://www.steelsoldiers.com/threads/transmission-light-issue.194948/post-2318019
Bulldogger

 

[engele]

in you have a 4 Speed, There is a disconnect relay behind the passenger Seat.