I went to the 1/4 mile track this weekend, and made a couple of passes in the truck just to play around. My first launch, I put it in 4hi and stalled up and when the light dropped, SPINNNNN! Just rear wheels. Nothing more. I had thought my 4wd wasn't right, but never got off-road enough to tell other than in the yard. What could this be? I hear action when I hit the buttons, and they're good. In fact, I soldered them just a few months ago after they DID mess up.

 

2 things happen when you engage 4wd. One electric motor slides a coupler on the shaft in the front diff and electric motor engages in the transfer case. You should get a solid green light on the 4hi switch. If you are getting that and no DTC's would have to be something mechanical in either I suspect.

 

Hey man! Yeah you were there, running the ***** off that beast. Sweet truck man. You know me as Pewturd.
I'm not getting Green lights. Mine are all amber. But no Service 4WD light. Any ideas?

Is there any way to test the actuator motor in the front, that you're aware of? I honestly don't know that my drive shaft is turning though. Let me explain:
I put OBX long tubes on the truck about 3 months ago. Despite heating to put a substantial flat spot in one primary, I was still having it hit the front diff yoke when turning sharply to the left. This is because the front drive shaft always spins. Well yesterday on my way home from Clay City, I thought about it so I hit some of the curves that used to do that, and NOTHING. Just thoughts. Any input would be greatly appreciated. I really highly value your opinion.

 

well the spot where the driveshaft and primary were hitting could have worn down, so now you dont hear it anymore.

 

I'm checking the service manual out. I'll post up when I find something. Betting its the encoder motor on the transfer case. There still may be some codes stored. If you can get it scanned.

 

clutch packs in t case could be worn out.had same prob on another truck.when i had it on the lift all 4 wheel would spin but back on the ground just the back,had to rebuild it

 

That can't be too bad. Me and Bluecat rebuilt my T56 when my car was 6-speed.
Thanks for any help you guys can offer. Maybe I should just man up and buy a manual with 4wd diagnosing info.

Problem with scanning is I think that would be stored in the BCM wouldn't it? That's not readable by HPT. Am I wrong here?

 

Hey Pewturd... thanks for the props. Had a great time at the track. The truck ran well, won the index trophy, new best and didn't break anything.

Oh one other thing, I am locked out of KYHP. Can you post something over in general forum asking someone to unlock my account. Thanks.

Here is a link to diagnose the front actuator. CLICKY

This info is from the GM manual. I got it here. https://www.performancetrucks.net/fo...d.php?t=404158