Surf 4WD engagement issue

[jono23]

I've recently replaced the front diff in my 1993 LN130 hilux surf. I checked 4wd was working by propping it up on axle stands and engaging 4 low and 4 hi. It seemed to run fine.

Now it seems I engage 4wd and the light sometimes comes on but only briefly for 5 seconds before going off sometimes it doesn't come on at all. Due to it being an automatic engagement i'm not entirely sure if the hubs engage at all.

Has anyone come across this problem before? Could it be electrical or possibly to do with the seal on the diff leaking?

Any ideas?


Cheers

[mike]

My light doesnt work at all and im sure its just the light as both mine drive in the front when in 4wd (locked front). To test (with or without locker), engage 4wd. jack front left off ground and spin. If it spins its not engaging, if it doesnt and everytime you try to spin it the front propeller shaft tries to turn then your in 4wd and its the switch on the diff playing up. check the contacts on that.

On these diffs only the front left drive shaft dis-connects. hence why you only need to jack this side to test.

[UBZ]

There are two electrical connections on a ADD front diff.
Front connection is a 4wd activation indicator. this tells the 4wd computer that the front diff has been engaged. if this is faulty the 4wd light will not come on. You can bypass this switch by joining the wires together.

Rear connection is a oil temp switch. this will dis-activate ADD 4wd if the front diff overheats. if this shorts out it will dis-activate 4wd.

Front Activation is controlled by two vacuum switches located in the engine bay just in front of the brake booster. I would be checking the vacuum lines for leaks as well.

There is also another 4wd activation indicator switch located on the transfer case . This could also be causing the symptoms you are describing.

I have also heard of the 4wd computers giving up the ghost and working intermittently.

Hope this helps.

C.

[jono23]

Cheers guys

Thanks for your advice. Will have a look at it on sunday and see if i can locate the problem.

If anyone still has anymore ideas, feel free to post them up.



Jono