Hi all, I have a 1990 80 series manual.

My center diff lock won't engage. And the dash light doesn't come on.

I have checked the dash switch its plugged in.
Plug on the transfer case is plugged in.
The transmission relay clicks when I have it in high range doesn't do anything in low range.

What can I check pls

Have you downloaded the FSM and looked at the wiring diagram, bloody confusing too say the least but there are two relays for the 2wd/4wd, I would start past the relay and manually engage the transfer motor with a power wire, if 4wd engages (no light though) then you can at least eliminate the transfer itself and work your way back.

The diagrams are as clear as mud though.

Barry

Thanks for the info, where can I download that from? Thanks and any idea where the second relay is?

In the website header, under the rocks "Factory Manual Downloads"
Mike

hi i had the same problem and its done it twice to me it was the actuator on top of transfercase easy way to check is see if its making noise all i done was just drop the cross member and pull it off and tryed it it worked but wasnt strong enough to turn the gear but i had a second hand one to try hope this helps.. allso theres 2 big plugs side by side on the right hand side on the firewall down the bottom if you go throught a bit of mud clean the hell out of them this also can cause it..

I had the same drama and mine was the transmission control box. Rh side kick panel little black box had green death in it.

and you could check the plugs up on top of you box are good