Diff Lock Not working

[Tonks4x4]

OK Help
Diff lock does not engage.

I have read all earlier posts. but still not cured.

I have had the car on the ramp and actuator moves freely and does lock rear diff as it should.
I have had the rear seat up and checked for leaks.
I have swapped the diff vacuum control unit
If i feed the pipes direct from the violet vac pipe it lights the switch and operates the diff as it should.
I have also used a different known working diff lock switch.

But still I can't lock/unlock the diff direct from the switch.

Does anyone have a wiring diagram so i can chase the wiring next???

Or do you have any other ideas that i have missed??

[fish]

Have you checked the lurid green vacuum container thats lokated right behind rear left "doortrim"?? (it´s located there on LHD coupés anyway) I had exaktly the same problems as you and there was a hole in that thing. fixed it and the diff worked fine.

[johne]

Wiring diagrams are on S2central.net

John

[Tonks4x4]

Wiring diagrams are on S2central.net

John

John could you send me a link. I have clicked on every link I can find on S2Central and don't seem to be able to find it?

[spink]

hmm,i wonder if it is the 1 way valve under the rear seat? sits about 6 inches from the diff controller.I had one go on my last S2 which was causing some weird stuff to happen to the diff switch(light kept flashing when boost was coming on).Can't say i ever tryed the diff lock on that one but its worth a try,i swapped one off another car but they are only about 8 quid new.

[Matt_D]

Your not trying to lock the diff straight from startup are you ?

You need to drive a couple of inches then try and lock the diff before it will actually lock

[Tonks4x4]

Ok I have checked the one way valve and all pipework again.

All good no leaks.
I have tried it with abs off, abs on forward and reverse
And I have jumped in and moved it both back and forth whilst pressing button, holding button, hitting button, smashing my head against the dashboard and all other combinations of self brutality to get this working.

Does anyone have a link to the wiring diagram so I can get an idea of what is happening?

[S2central.net]

http://www.s2central.net/S2_Schematics/

I need to put a proper link for this into S2central... Let me know if you need help deciphering the schematics, but difflock is pretty simple circuit. Maybe something stupid like bad supply or earth to the controller unit.

[Rusty]

I've cut the blue and white wire so it never goes off :mischeif:

[fish]

Did you try my suggestion??

[Tonks4x4]

@ fish yes i have tried your suggestion thank you.

however thank you to s2central i have had the wiring diagrams and have traced it to a small break in the black and yellow wire under the rear seat where the metal braces are under the seat base.

The diff lock switch has a black and blue feed which when pressed sends a 12v pulse to the diff lock actuator control box to change the flow of vacum.

All sorted and works spot on thanks for the help...

[AUDIS2avant]

hello.
Great to here you got it working
But can i ask, how can you feel it´s on and what are the advantages/disadvantages?

[Tonks4x4]

hello.
Great to here you got it working
But can i ask, how can you feel it´s on and what are the advantages/disadvantages?

When it's engaged try and turn full lock on tarmac and you can feel the car feels very different as though it's trying to drive straight on. You can actually here the tyres trying to skid on the rear.

The advantage is when it's in snow or mud it has better traction.

[AUDIS2avant]

so you can use this on the strip to get better takeoff then also?

[Tonks4x4]

so you can use this on the strip to get better takeoff then also?

Yes it can be done but there is some debate over whether it will break your diff etc. on other posts if you search for them.