What did you do to your NBS GMT800 Tahoe/Yukon Today?

[rgosart]

Been getting the service 4WD message pretty consistently lately, and interestingly, the tcase seems to start out in Auto 4WD rather than 2WD where I leave it. It goes away quickly, usually right after turning off, and then pops up again a day or two later.

Finally caught it with the tech 2, and I have a C0327 code, so figure I need to replace the actuator motor, or possibly the TCCM.




Also getting the loss of comms message, and it won’t actually read data from the tcase as well. Here’s a video when I try to read the tcase data:

A couple years ago, I was getting a service 4wd message intermittently. I never did get a code out of it (I don't have a tech 2). I was checking out the connections one day to make sure there weren't any broken/corroded wires. After I unplugged everything and plugged it back in, the message has not come back. Maybe I got lucky, but it has been years since I have had an issue.

 

[Sam Harris]

A couple years ago, I was getting a service 4wd message intermittently. I never did get a code out of it (I don't have a tech 2). I was checking out the connections one day to make sure there weren't any broken/corroded wires. After I unplugged everything and plugged it back in, the message has not come back. Maybe I got lucky, but it has been years since I have had an issue.

Ha! Nice. I’m hoping when I pull the motor off, and check the wiring it will go away too. [emoji16][emoji106]

 

[Doubeleive]

Ha! Nice. I’m hoping when I pull the motor off, and check the wiring it will go away too. [emoji16][emoji106]

If it turns out to be the motor and if you are so inclined you can fix it, there is a gear inside that goes bad youtube has video it's been a long time since I watched it but I know there is one guy that showed how to do it.

 

[Bear77]

Finally done!!

So since I hardly go into cargo area for the moment, I didn’t notice this



Does this look right? It’s the parking brake?



Condition of the other side. Was on its way out too...



Brake pads (old ones)



Side by side(old versus new ones)


Have no clue what the yellow stuff is. I thinking factory yellow loctite?



More pic’s to come


Sent from my iPhone using Tapatalk

 

[Fless]

Finally done!!

So since I hardly go into cargo area for the moment, I didn’t notice this



Does this look right? It’s the parking brake?



Condition of the other side. Was on its way out too...



Brake pads (old ones)



Side by side(old versus new ones)


Have no clue what the yellow stuff is. I thinking factory yellow loctite?



More pic’s to come


Sent from my iPhone using Tapatalk

If I'm not seeing things, that parking brake shoe doesn't have any friction material on it.

 

[Bear77]

Greased up new caliper, installed the new pads, and bled the brakes all around...

Caliper mounted on, new banjo and washers installed...



Side by side comparison with the non-broken rotor. New one just seems smaller to me and in this pic, you can tell...




Sent from my iPhone using Tapatalk

 

[wjburken]

If I'm not seeing things, that parking brake shoe doesn't have any friction material on it.

View attachment 262979

Matches the rest of the pads!

 

[Bear77]

If I'm not seeing things, that parking brake shoe doesn't have any friction material on it.

View attachment 262979

That’s what I thought. So I guess I will be doing the parking brake soon. Putting high up on my to do list!

Matches the rest of the pads!

Yup...


Sent from my iPhone using Tapatalk

 

[Fless]

Ha! Nice. I’m hoping when I pull the motor off, and check the wiring it will go away too. [emoji16][emoji106]

If I were you I'd definitely start with checking and cleaning the connector for the encoder motor pigtail, and the connector on the TCCM. If not one of the connectors, it's more likely that the encoder motor is bad. If you can get connections to work, the Tech 2 can command the various 4wd modes and you can see what mode is really in effect.

For the encoder motors, I think that Dorman is the only company that makes them new now. From the research I did for mine, the rest in the field are remans. As @Doubeleive said, the encoder ring is replaceable.

EDIT: I looked back at my May 2019 invoice for my AC Delco encoder motor and it was new, bought from Amazon but from some other place. Cost me $265 and was NEW. I had sent in the Dorman that was a couple of years old for a refund since it quit, although it may have been stressed by the TC before it was rebuilt.

 

[NoReverseYukon]

That’s what I thought. So I guess I will be doing the parking brake soon. Putting high up on my to do list!

Sent from my iPhone using Tapatalk

Give the parking brake cable tension bracket a blast of PBlaster now and every so often to help w/ loosening to allow slack for easier removal/reassembly. I wasn't so lucky, and getting that cable back into the actuating lever was a PITA!