NEED HELP 2002 TB LS 4WD front wheels not engaging

[moneymike]

Hey guys, been reading through a bunch of posts and articles about front wheels not engaging when 4Hi is selected and what I'm thinking might be that the front axle disconnect might need rebuilding. If anyone could offer me advice or any knowledge on this matter I'd appreciate it. What I've done so far is confirm that the encoder motor on the transfer case is working, because when I put the switch in 4hi I cannot spin the driveshaft. However, the front wheels will spin freely without the driveshaft spinning. Went and put a known working front axle disconnect actuator from a GMC Envoy on and can hear it and took it off while plugged in and could see it moving when 4hi is selected. When I put the switch into 4Lo the rear end is at 4lo speeds but again, no movement at the front wheels. I would appreciate it if anyone else has an opinion on what it might be

Edited to add: no service 4wd lights on and when selecting 4hi the switch will blink, you can hear the whirring and the motor and the light will stay solid on 4hi but not be driving the front wheels

 

[Mooseman]

This is what you need to rebuild the disco:
Disconnect rebuild (OffRoadTB.com)

 

[TJBaker57]

However, the front wheels will spin freely without the driveshaft spinning

To be clear. Can you spin ONE front wheel only , while the opposite front wheel and the front driveshaft do NOT spin while in 4hi or 4lo?

 

[moneymike]

This is what you need to rebuild the disco:
Disconnect rebuild (OffRoadTB.com)

right, I did read through that which is how I was coming to this conclusion..

To be clear. Can you spin ONE front wheel only , while the opposite front wheel and the front driveshaft do NOT spin while in 4hi or 4lo?

If I spin just one wheel, it will only be that wheel that spins and driveshaft doesn't spin either, so yes you are correct

 

[TJBaker57]

If I spin just one wheel, it will only be that wheel that spins and driveshaft doesn't spin either, so yes you are correct

OK then that is indeed a failed disconnect. If the opposite front wheel was to spin the other direction that would perfectly normal behaviour. Just wanted to be sure you didn't go through the hassle of taking out a disconnect that was OK!!

 

[TJBaker57]

Went and put a known working front axle disconnect actuator from a GMC Envoy on and can hear it and took it off while plugged in and could see it moving when 4hi is selected.

What happened to my 2002 was an internal thrust washer inside the disconnect wore down and coupled with a worn output shaft bearing it slipped out of position and prevented the movement of the shift collar/gear. The actuator would travel its' full distance and indicate to the tccm that it was engaged but in fact all it did was compress the spring inside the actuator mechanism and the shifting fork never moved due to the blockage!!

Here is the washer




And if you look very closely at the base of the extended cylinder here you can make out a single coil of the spring inside the extending actuator...

 

[moneymike]

OK then that is indeed a failed disconnect. If the opposite front wheel was to spin the other direction that would perfectly normal behaviour. Just wanted to be sure you didn't go through the hassle of taking out a disconnect that was OK!!

well that's better news to hear.. although it could still be something in the front diff? Im planning on swapping the known working disconnect assembly in the next day or two and hoping it clears it up, but if not I'm looking at diff problems or damaged splines right?

What happened to my 2002 was an internal thrust washer inside the disconnect wore down and coupled with a worn output shaft bearing it slipped out of position and prevented the movement of the shift collar/gear. The actuator would travel its' full distance and indicate to the tccm that it was engaged but in fact all it did was compress the spring inside the actuator mechanism and the shifting fork never moved due to the blockage!!

Here is the washer

View attachment 91785


And if you look very closely at the base of the extended cylinder here you can make out a single coil of the spring inside the extending actuator...View attachment 91786

looks like you probably experienced and fixed what my problem is.. thank you for your help and I'll definitely write back and let you know if the swap fixes it

 

[moneymike]

UPDATE: The swap of the disconnect seemed to have solved the problem.. However after installing it and testing after the first time, there was apparently too much grease inside so we tore it all backapart and tried again with 100% everything working successfully. Thank you everyone for your input!