Diff lock fails to engage - what to check first?

[SteveH]

I just bought a used '98 4Runner / 5 speed / diff lock, 110K miles. The orig. owner told me he used the diff lock once or twice, but I have engaged it several times in 4Lo and done donuts, romped on the throttle, etc. and yet the light flashes and it refuses to engage the lock. The PO hadn't used it in years, so I'm sure that it needs some exercise. It's been in Colo and I don't believe the rear axle has been under water.

What should I check, in order of likelyhood? I'd rather not tear into the solenoid setup if there's something else I should be looking at first. Do I need the service manual to do remove the solenoid and study/debug/rebuild that?

Thanks,

Steve

 

[Cube Dweller]

Steve- I'm pressed for time, so I'll give you a quick suggestion- search in the 80's section. The lockers are basically the same, and many of the 80's guys have had similar problems and resolved them. The locker assy's are pretty simple. You can pull the plug and try to engage the locker by applying 12V to the pins. RavenTai had a few posts in the 80's section on how to do this. This will tell you if it's a locker issue or control circuit one.

 

[SteveH]

Thanks - and...

I've read all the 80 stuff - on Slee's site and many others. I guess I should try a few more donuts, then have it in 4-low on blocks and tap the actuator a few times with a rubber mallet or brass hammer, and then go try to get it to engage.

If all else fails, I'll pull it apart for an inspection. I'm trying to make that my last resort.

Steve

 

[Jukelemon]

It would be very simple to test the control circuit with a voltage tester. That way you know at least where the issue issue is. I really doubt that it is anything other than the actuator.

 

[SteveH]

More flogging did it

I ran the truck in 4Lo some more last night and the diff finally locked up. I engaged and disengaged it several more times and did some good uphill dirt burnouts, and it's working just fine. I guess I wasn't patient enough. Thanks for the tips.

Steve