1992 Chevy S-10 4WD Not Disengaging - Constant Vacuum to Fr

DAMIANS10

MEMBER
1992 CHEVROLET S-10
6 CYL
4WD
AUTOMATIC
149,000 MILES

1992 S-10 Blazer, 4.3L V6. Manual 4X4 engagement(not push button). My problem is that my front differential is stuck in 4WD mode. The vacuum actuator which locks the front diff is receiving constant vacuum even when the shifter is back in 2WD mode. It will release if I pull the vacuum lines off the top of the Xfer case (when the truck is not running) and I can physically hear the cable actuate in the diff, so I know it is moving, and then the light will turn off indicating it is back in 2WD. But as soon as I start the truck back up, the actuator receives full vacuum and we are back locked. My guess is either something with the vaccum switch on the Xfer case, or the vacuum is not releaseing from the Xfer case via a vent or something.

I would appreciate any troubleshooting suggestions.

Thanks

1 Reply

BILLYBOBASAN

MEMBER
12 POSTS

Hello, The problem will be in the switch on the transfer case. Just screw it out with a 7/8ths inch open end wrench. Clean dirt away from around it first so it wont get into tfcase. It has a little ball on the end of it, you will find it stick into the switch. There was a recall on these vehicles where this switch was replaced. You might check & see if yours was included & if its been done. If not Im sure this switch isnt very expensive & you can install it yourself. Just make sure you install the 3 vacumm hoses up to the switch correctly.
Good luck,
Billbob