Every once in awhile, my trusty XT6 pitches a subie fit. When i start it, the trans defaults to "limp home" mode. (center diff locked, trans in 3rd) There is no power light on the dash, or any other telltale. Im thinking its a heat related issue, because it started this last summer, then didnt do it all winter. Now that its getting hot out, its getting worse.

 

My questions are: Has anyone else had this problem with thier early 4eat, and am I gonna have to replace my TCU before it strands me.

The power light works but doesn't blink even when in limp mode?
Is it possible to go into limp home without a trouble code?  I would think so only with a mechanical failure...just a guess.

 

Standard questions:

1. fluid level is good

2. no bubbles in ATF when this happens

3. trans pan isn't dented?

4.  no check engine codes?

 

Have any critters lived in this car (chewing wires)?

 

I wonder if maybe a ground issue...causing the TCU to simply be "turned off"

 

If not I'm suspect of mechanical issue, pure speculation based on nothing at this point though.

Edited June 3, 201312 yr by grossgary

My speculation would be for ground or power issues to the TCU, pretty much same reasoning/basis as GG.

The tcu is inside the panel behind the drivers seat. Iirc the ground to it is unreliable, like under the seat or something where it can get corroded. Does a key turn fix it?

I'll check the ground asap.

Yes a restart fixes it. (is the trans powered by microsoft? lol)

Level is spot on

No foam

Pan isnt dented

No cel on

Power light flashes after a reboot

No known critters in the car

Edited June 3, 201312 yr by crazyhorse001

I

Power light flashes after a reboot

 

don't know what you mean by reboot- after restarting - be nice to get that code though or check if it's got one.  if it's flashing 16 times on start up that means there's a code somewhere - i'd get it.  that's going to tell you a lot unless you're unlucky.

I have seen bad electrolytic capacitors inside the TCU cause problems like this.  That would certainly be heat related.  Could be a bad solder joint too.