4x4 won't work when cold

[H2Oboy]

So... the back story. Last winter I found out, the hard way, my 4X4 didn't work. By the time I got it all figured out and fixed it was getting into springish weather. I replaced the TCCM kept (it "forgetting" to work) and the encoder motor would work sometimes but not consistently, and a new selector switch (looking back probably didn't need this). Anyway every once and awhile I would still get the 4X4 light when I first drove it then some time while out and about it would shut off and everything would be just fine. Well I began putting together that whenever the temperature was below about 35 F, I would loose 4X4. Now that we are coming into fall here and getting some cooler nights i'm starting to get the 4X4 light on again, now at around 55 F. Again once the air temp is warm enough or I drive it for awhile then restart the light goes off and everything functions fine.

Anyway I knew I probably would have to wait until after summer to work on this (to get the code) but I'd like to knock it out before i really need 4X4 and it gets too cold out.

I don't know what the code actually is cause I'm having a friend help me out and I haven't tried to arrange a time to meet him at his shop as this can be difficult finding a time. Looking for suggestions, tips, or comments.

 

[Mooseman]

I had that exact same issue except that it would fail when it was below -20C. The TCCM was a weak point in 2002 and was prone to failures. If you can find another one from a junker, 2003 and up, it should fix your problem.

 

[H2Oboy]

A new TCCM even tho I have a "new" one this past spring?

 

[Sparky]

If you got a TCCM from 2003 or newer then you should be fine there.

Sorry if I misunderstand your post but you did or did not replace the encoder motor?

 

[H2Oboy]

yep the encoder motor got replaced. As for the TCCM it was from rockauto for a 2002. I assumed it should be a good one, even tho it sounds like the 2002 year had problems. ( I would hope someone realizes that no one wants to replace a bad part with another bad part).

 

[Sparky]

If you had gotten a brand new one then yeah it would not have been a troubled part.

Have you checked the splined disconnect on the passenger side and the actuator? If not, take the actuator out (2 bolts and a harness), take it apart, and see if the contacts are all OK. They may be cruddy and when cold the fingers withdraw just enough to not make proper contact with anything and it doesn't read properly. Also spray the connection end with some contact cleaner while you're at it (with the truck off of course).

 

[Mooseman]

Could also be that the grease is so congealed that it won't let the disconnect work properly.

 

[H2Oboy]

ok thanks for the ideas. i'll have to take a look at them here sometime this weekend. Other than the Tccm, encoder motor, actuator, and the switch is there any other electronic parts in the system?

Sparky- I re-read your post, what is the splined disconnect? is that in the actuator or an internal (mechanical) part?

 

[Sparky]

The splined disconnect is on the passenger side of the oil pan. The CV axle goes into it. The actuator is the black plastic thing that is bolted to the side of it with a wire harness connected to it. It engages and disengages the passenger CV axle.

 

[H2Oboy]

I know its been awhile but...
Here's what I've learned. Got frustrated and took the TB to the dealership and had my friend look at it. He said it looks like its the ignition (apparently got a code for it). Pretty crazy. But then I remembered reading a post long time ago about the ignition going bad causing weird issues. ( I think I was trying to troubleshoot a generic misfire codes at the time, not 100% sure) Anyway hope this fixes my 4x4 issues when it gets cold.