Trans light always on!?

[AWRVEE]

I need some help I have a 6.5 turbo with 4l80e. The trans light stays on with ignition off causing my batteries to die. She drives just fine otherwise.
I've changed the relay (twice now just to be certain) the TCM, and checked the breaker. The breaker was bad so I used a 15a jumper. I've tried researching and only found the relay being the issue other than one occurrence where someone ran a new wire to the relay.


I'm in central Florida also so if anybody has a shop close.

 

[Mogman]

Welcome to the forum!

 

[Mullaney]

I need some help I have a 6.5 turbo with 4l80e. The trans light stays on with ignition off causing my batteries to die. She drives just fine otherwise.
I've changed the relay (twice now just to be certain) the TCM, and checked the breaker. The breaker was bad so I used a 15a jumper. I've tried researching and only found the relay being the issue other than one occurrence where someone ran a new wire to the relay.


I'm in central Florida also so if anybody has a shop close.

.
Welcome to the Outfit!

Maybe a picture or several of your new-to-you truck would be good. After all, we are picture hounds here... Might be worth your time to download the TM's (Technical Manuals) too. Yeah, I know. It's a lot more fun to rip and roar down the road than looking at a stack of stuffy old books - but there are troubleshooting flow charts in those books.

Might be that sharing the truck type would help you get a better response as well. (info is on the dash plate)


Welcome to the group.
.

 

[Mogman]

This is a fairly common issue, I have searched the past threads and there seems to be no clear answer.
Here is the supplement for the 4L80 and a snapshot of the schematic, make sure there is NO voltage between 290C/291C and ground with the run switch off, do not disconnect it to check, use a sharp probe to pierce the insulation of the wire.
Report back if there is any voltage there.

 

[AWRVEE]

.
Welcome to the Outfit!

Maybe a picture or several of your new-to-you truck would be good. After all, we are picture hounds here... Might be worth your time to download the TM's (Technical Manuals) too. Yeah, I know. It's a lot more fun to rip and roar down the road than looking at a stack of stuffy old books - but there are troubleshooting flow charts in those books.

Might be that sharing the truck type would help you get a better response as well. (info is on the dash plate)


Welcome to the group.
.

Appreciate it, not sure what the truck info would do for help. It is a A2 helmet top with the 6.5 turbo and 4l80e. I have had the truck for a few years with no issues until about a year ago. I have the TMs which is why I have done what I have with trouble shooting.

 

[AWRVEE]

This is a fairly common issue, I have searched the past threads and there seems to be no clear answer.
Here is the supplement for the 4L80 and a snapshot of the schematic, make sure there is NO voltage between 290C/291C and ground with the run switch off, do not disconnect it to check, use a sharp probe to pierce the insulation of the wire.
Report back if there is any voltage there.

I do have voltage with ignition off on the wires. I will need to check which one but I remember one was hot

 

[Mogman]

I do have voltage with ignition off on the wires. I will need to check which one but I remember one was hot

Yes 291A/290B will be hot but 290C/291C should not, remember to check with the wires connected

 

[Mogman]

Report?

 

[86humv]

The relay aft of battery box do stick on sometimes....wack it with a rubber hammer.
If that turns light off....you need a replacement.