4x4 problem? (1 Viewer)

[Stevevoid]

Lj70 1986 2.4 td
Evening all, I’ve recently bought this old lady and she hasn’t moved for 9 years so I’m working through various problems...
When I put her into 4x4 mode via the H4 button on dash, 50% of the time, the green light doesn’t come on and she won’t go into 4x4. The other 50% of the time it’s fine... From what I understand there’s a vacuum switch that engages it and unless that light come on, then 4x4 won’t work. At first It happened when I was off-roading and I presumed it might have been due to water getting into one of the contacts on the transfer box for example, but she’s been indoors now for a month and it’s still an intermittent problem. Some things that I have noticed that may or may not be relevant: it’s slips out of
4x4 low quite often, not 4x4 high. Don’t think that’s related but obviously something I need to sort out? There’s a winding noise when 4x4 is engaged, not entirely sure what that is.
Any suggestions, advice and experience appreciated, thanks!

 

[clintnz]

There are two vacuum solenoids high on the firewall in the engine bay - follow the two vacuum hoses up from the transfer case to find them. There you can connect either hose direct to engine vacuum & check if the t-case is shifting into & out of 4wd ok (easy way is to leave the gearbox in neutral, hubs out & reach under to spin the front driveshaft, if it turns freely then you're in 2wd)

If the shifting in the transfer case checks out ok then you can move on to making sure the vacuum solenoids are switching properly. You can take off the vacuum lines & feel for vacuum as you switch, check that the solenoids are getting voltage etc. Not sure on how the earlier models are wired but my LJ71 had a '4wd control computer' under the dash that started failing intermittently & not switching out of 4wd. I wired in a change over relay instead.

Cheers
Clint