No HIGH 4 dash light-plus intermittant skidding on some hard turns y

[Bamurru Lurker Find all posts View Profile Close Bamurru]

My questions show my lack of mechanical skills so please be patient
context 2009 120 series Diesel
Firstly, the dash light for H4 isn't lighting when i move the small stub into the usual position to engage the diff lock but DOES light wheni stop and move successfully into low range. How do i know if H4 is actually engaging and it is just a light sensor issue. Or is something faulty with H4 engagement? Any other thoughts and advice, please? This vehicle has had a long history of 4wd use.
Secondly sometimes it now seems a rear wheel occasionally grabs and skids when i do a sharp or u turn at low speed. Not sure if this is just with hard turns on cement or gravelly bits of bitumen. I try different situations and its only happening occasionally. Cheers all

[Bamurru Lurker Find all posts View Profile Close Bamurru]

After some further thinking i am of the view that the intermittant wheel skidding on turns is to do with the diff lock being inconsitantly engaged. So i have a problem between H and HL with the stub lever not making any change in high range...i think i have managed to get out of HL and undo the diff lock ( with no further skidding turns) by reversing backwards for a good 50metres and pulling back on the stub lever. Do i sem to be on the right track diagnosis wise? Other suggestions?

[ptommo59 Senior Member Find all posts View Profile Close ptommo59]

From the 120 Prado wiring diagrams and 2009 parts manual the 4WD/Centre Diff Lock indicator on the dash uses the same switch and wiring to activate in both high and low range so based on your symptoms seems the centre diff lock actuator did not fully engage when you initially switched to HL, but did when you went through N to LL.

The owners manual says that the 4WD light not coming on when going from H to HL can happen and you should accelerate/decelerate to assist the centre diff lock to fully engage and get the light on.

Seems from your second post it is engaging sufficiently to lock the centre diff but the actuator rod/fork is not going far enough to activate the switch (must have a section on the rod with a raised point to push on the switch actuator pin).

As a suggestion maybe just make sure the switches are all full screwed in/tight in the transfer case housing just in case that is enough to cause the issue. If nothing obvious you could pull out and lightly lubricate the switch with WD40 or similar just incase the actuator is mechanically sticking and also check the electrical connections are ok with a multimeter (should be below 1 ohm when pushed in and above 10Kohms when not pressed)

Hope that gives you something to work with.

[ptommo59 Senior Member Find all posts View Profile Close ptommo59]

Also just realised the D2 low range and D1 centre diff lock switch connectors are identical (blue 2 pin connector).

Is it possible someone has reversed the connections at some stage as that would also cause what you are seeing on the 4WD light?

[Bamurru Lurker Find all posts View Profile Close Bamurru]

Thanks ptommo59 I really appreciate you responding. Sorry i didn't get back to you sooner but have been out camping in the 120 this long weekend. You have indeed given me something to think about and work toward. Cheers

[Bamurru Lurker Find all posts View Profile Close Bamurru]

Eventually got someone to look at the issue....and ptommo59 your assessment was correct. Mechanically all is functioning well with the diff lock and low range....and its just the HL light that is failing. I will fillow your cleanup advice before looking at a replacement actuator light. Thanks again