Service 4wd Light
 

I have an 01 2500HD 4wd... My Service 4WD light came on the other day, it stayed on for a couple days then went out... The selector switch stopped working and i am now limited to 2wd... I put a new switch in the dash and still no luck... I have an actuator on order and awaiting that... Any suggestions or other experiences???

what else do you have on order? the actuator in the front diff or the encoder motor in the transfer case?

The actuator is on order... What is the encoder motor in the transfer case???

Motor on the t-case is shot

motor on the t-case??? is this another easy fix like the other parts?

Instead of guessing/replacing everything, how about checking the codes in the TCCM (Transfer Case Control Module) to see what direction to go in. :humm:

I've got a SuperChips tuner with code reader, but not sure if that's the same thing needed or not... I'm not throwing any codes on the 4wd with the superchips reader if that helps... Sorry for the ignorance, thus the reason i'm posting... :s:

That will not read that code. To do that you will have to got to the dealer and have them read it and probably charge ya 75 to do it but it will tell you exactly whats going on....

yes u will need to go to a dealer cuz u need the gm tech2 scanner to read dtc's in the in the tccm. that will tell ya exactly wat it is

You'll need a little more high tech tool than just a engine code scanner to see these codes. If you have a friend with a Tech2, Snap-on or OTC scanner they will be able to check it out. You might be able to go Vato-zone and see if they can access the codes, but I don't know if they can or can't.

we have bucket trucks and pickups at work. I'll see if the mechanics there can read the codes for me... Thanks everyone

:argh: ok, so far i have a new selection switch in the dash and a new actuator on the front differential... Still NO 4x4... I will check with the mechanics at work on the scaning of the TCCM... I will post as i make progress... :argh:

motor on the tcase is my guess... :w2:

Its about the only thing left... :argh: :scare2:

Not that bad... Done more than a couple on the lift at work. Doesn't take long to swap it in and test it out. Don't fix it put it back in the box and send it back :D

It's only an extra few hundred for the encoder motor and couple hundred-ish for the TCCM. If that doesn't work, then the only thing left to check is the wiring and fuses. :tu:

Why diagnose when you can just replace? :pca1:

The mechanics at work used the GM Tech2 scanner today and it came up as control module or something like that... Which i assume is the TC motor... He reset my ABS light (ABS sensor on front driver is bad) and it re-appeared immediatly... All fuses are good, there are no relays that we know of... We replaced a 20amp fuse for the "service" fuse (???) and the service 4wd light came back on... The new dash selector swith NOW shows the 2wd option lit... It doesn't change regardless of any other buttons pushed - the 2wd light stays lit... He's thinking it might be a bad wire somewhere or bad connections... I don't mind replacing the tc motor if that will fix the problem... We were running short on time tho today, so we will continue the research later... Just wanted to update the progress here... Any more thoughts after hearing this??? :pca1:

Wouldn't happen to remember the exact code would ya?

You say 'control module', so I would go in the direction of the Transfer Case CONTROL MODULE, more so than the encoder motor. It would be nice to have the code so we can steer you in a more deffinant direction.

I thought the guys from work told me that the control and motor were both part of the motor assembly... :humm: I will re-converse with them and get the exact code and some dang answers... :bat:

Nope. There is a TCCM that is located behind the 4wd buttons on the dash. Then there is the Encoder Motor that is on the side of the t-case. Both are known to go out. Both are expensive.

Looking just got one in at work that scanned as being a decoder motor. Didn't solve the issue. Tried a sector switch that we had laying around that was known to be good doesn't work. Got a wiring diagram for today and wires are gone be traced woohoo :D let ya kno what I find...

Also yes you can just buy the motor for the tcase. We opt to just buy the whole setup.

I'm by no means pushing this idea, but our mechanics here at work say that there is a electrical board inside the motor assembly on the tc... They said, out of all the trucks they've had to fix that it's always been the switch on the dash, the actuator, or the motor assembly on the tc... :s: i will be with a bunch of ole country boys this weekend... Maybe we can put this thing up on a lift and check the wiring and all, if nothing else narrow some things down... I will update as i get into it and be awaiting Red Rattlers findings... Thanks again guys :rocking:

sorry to take so long to reply what was broken here...

We replaced the 4wd transfer case motor and she works like new... I have all 4wd capabilities again...WOO HOO... :jump:

Thanks everyone for the help...