"Service 4wd" message
 

Hey guys, I need some help on this issue. This is a 04 Suburban 2500 4x4 with the LQ4/NP 246. I bought it from the guy and it was his Dad's and he said this message popped up but it worked just fine in 2wd, which is the case. Last summer I got under there and the encoder motor had the wires broken off. It almost looked like they had caught the front driveshaft the way they were damaged. I soldered the wires back but it didn't help. I checked and double checked all the fuses and they are good. I thought the dash lights on the dash for the TC were working, but now seems like none blink at all.

What would be the proper way to diagnose this? I suspect either the switch or the encoder motor, but not sure; I'm kinda new to the 4x4 drivetrains. I checked for codes and I only have a fuel sender high voltage (this popped up recently through.) Otherwise no codes. Swap to a manual shift TC?! LOL

Manual TC swap FTW

You are sure your solder job was good? I would not be surprised if the encoder motor is damaged.

I felt pretty good about the solder job. The wires are pretty thick and I even put clear heat shrink tubing on them. You have to remove the front driveshaft to get to it, so I would probably just go ahead and replace it. It's around $200, so I would want to make sure that's the issue. The videos I saw for replacing it say to put the TC case in Neutral. How would I do that if I'm stuck in 2HI?.

Re: Manual TC Swap. LT did a NP246 to NP241 on that OBS 2500 Suburban he sold. It was pretty easy. I'd just have to remove the center console for the floor shifter, but I was probably going remove it anyways. I'm not sure if the electronics would be the same for this 04 model? Do these have some sort of traction control circuitry used with the EBCM? Maybe?

Edit: looks like the 2500 models did not have Stabilitrak as an option.

Perhaps putting the truck in neutral puts the t-case in neutral. Not sure how it works on the auto- t cases

T case and trans neutral are 2 separate neutrals

You can chock the truck, put the trans in neutral, remove t case encoder and move t case manually into N

When I have an auto case die, I do a 241 swap because... 246 is junk imo

That is what I thought.

Um, well I was contemplating tearing into the NP246 to address the pump rub issue.

The NP241 came in the GMT800, right? Just find any 2500HD (to get 32 spline?) with the floor shifter and do some electronics? I found this link that describes some details of the swap: https://www.motortrend.com/how-to/16...r-case-delete/

This is the truck I was thinking (more like daydreaming, LOL) of doing a SAS on that other thread I created BTW.

Don't replace your encoder motor yet. Can be a big waste of money. Take it off, take it apart and change the encoder ring.
After having the same issues I had a 6 month old ACDelco encoder motor fail, swapped the ring and good as new.

Should be Part# 88962315

$14 on RockAuto

Thank you. I was thinking of opening it up just to see the inside of the encoder motor.

I just got and downloaded all the AllData wiring diagrams for that specific year and model. Seems like $20 (for 1 month access)well spent for diagnostics. Highly recommend it.

Will post follow up...

Yeah no problem. This is all fresh on my mind cuz I had my 246 tore apart yesterday. Upgraded to a 32 spline input, added a case saver, and new seals. Its a little more complicated than a 241 but its not too bad. The snap ring on the tail shaft really sucks tho.

I got this case used and before I installed it I went ahead and threw a new encoder ring on just for good measure. Just be mindful of taking it apart, to put it back in the same orientation as you took it apart. Prolly best to watch a YT video on it.

And yeah I like to keep a subscription to AllData Diy for my truck, makes things way faster to diagnose.