jlewis

I have automatic locking hubs for my v6 auto, but something doesnt work. When i shift to 4wd the 4wd light does not come on however it feels like everything locks in the steering get stiff but only one rear wheel spins. I have checked the fluid and vacuum lines and found nothing wrong. Does anyone have any suggestions?

MMA_Alex

what year is it? are you sure you have auto hubs? or is it the ADD?

frankjake

If you have ADD and the 4x4 light does NOT come on, it could be a vac hose. When I had my A/C recharged, the next trip out, the 4x4 would not engage and the light would not come on. I checked and checked and finally found a vac hose off right near the inlet connection for the A/C.

DiskDoctr

I've also see a bad switch. The vacuum line was okay, we swapped in another switch and viola!

I don't know if there is a way to bypass the switch? Connecting the vacuum lines temporarily to test??? Anybody know?

-DiskDoctr

midiwall

Try these previous threads where people talk about troubleshooting no lockup in 4WD:

https://www.yotatech.com/forums/f116/4wd-wont-work-need-help-86349/
https://www.yotatech.com/forums/f16/diagnosing-no-4wd-lock-up-58634/

^VooDoo^

There is 2 wires going to the switch on the front diff make sure they are plugged in.
If you checked the vacuumlines, Even the ones going under the front passenger fender, Then Check the VSV's, The 2 little relayvalves on the upper passenger fenderwall.
Theres a blue one and a red one, In 2H the blue one should click as you unplug and plug it in, The red on should do the same when you are in 4H and 4L.

jlewis

Thanks guys for all of your help I now will start my process of elimination with your advice. Thanks.