Diff Lock Lights - What Exactly Prompts Illumination?

[Mickyfin]

I know my 4x4 is working fine, but am aware I need to troubleshoot my rear locker as its not functioning as should, so printed out the troubleshooting guide, and will check it when weather permits.

This leads me to the question, when I pull my rear locker, no light illuminates, so what exactly prompts the light to illuminate? Is there a built-in check system, so when when said locker is working, the light illuminates, and when not working, light does not illuminate?

I'm just trying to figure out if I have a blown bulb, and the light would light up when locker pulled, and locker not actually working etc.

Hope that makes sense?

[Aidan]

tell tell switch in the gearbox above and behind the vacuum unit is switched to closed circuit when the pin has been pushed in far enough to lock the diff, there's a depression in the pin where the tip of the switch normally sits, as the pin move the slope at end of depression pushes the switch, it only moves just over half a mm to make positive contact
you can reach the plug and remove from the switch and if you bridge the contacts on the plug the bulb in the dash should light that tests the circuit, testing the switch isn't easy cos of access, testing the difflock, well with one rear wheel in the air you should, handbrake off, be able to rotate wheel slowly against the vc, with difflock on you won't be able to rotate it as it will be locked against the wheel that is still on the ground

[Mickyfin]

Ah I see, thanks for that Aidan, makes sense. Will give those a try.

[KarlT]

I understand front diff-lock is different. What should it do in a perfect world?

[Mickyfin]

I understand front diff-lock is different. What should it do in a perfect world?

Some detailed info in this thread here about diff locks..

http://www.thesamba.com/vw/forum/viewtopic.php?t=488026" onclick="window.open(this.href);return false;

[syncropaddy]

I understand front diff-lock is different. What should it do in a perfect world?

As far as I know the only difference with the front locker is the knob on the dash which has to be twisted to operate (a bit like a few people I know). It uses the same parts - same locker ring, same diff housing, same actuator and same light switch ..... Principle is the same.

Aidan where are you?

[KarlT]

Yeah, same parts but I think the electrics give, or should give, more notice that it is going/trying to engage. Flashing diff-lock light?

[jebiga41]

Yeah, same parts but I think the electrics give, or should give, more notice that it is going/trying to engage. Flashing diff-lock light?

Yep it's a safety feature

[tencentlife]

Yeah, same parts but I think the electrics give, or should give, more notice that it is going/trying to engage. Flashing diff-lock light?

Some outfit over here had the same thought, apparently, so they came up with a little add-on system that senses both the vacuum that would be present on the engagement side of the vac servo when the valve is pulled, which makes the light flash, and also senses the normal location switch, which makes the light glow steady. So, pull the knob, light flashes until the lock engages, light goes solid.

VanCafe sells it:
http://www.van-cafe.com/home/van/page_1 ... units.html" onclick="window.open(this.href);return false;

I think it's a pretty neat idea, simple in concept, I'd like to know what they're using for cheap vac switches to do this economically, because I have many many uses for cheap vac switches but the ones I use are $30 apiece.

[Mickyfin]

That sounds interesting, and a cool addition.

[Aidan]

when they work and are used reguarly the rear one is so quick you wouldn't see the flashing when used appropriately, but maybe useful if you've a child in the front who pulls things mind

[bikermike87]

I understand front diff-lock is different. What should it do in a perfect world?

As far as I know the only difference with the front locker is the knob on the dash which has to be twisted to operate (a bit like a few people I know). It uses the same parts - same locker ring, same diff housing, same actuator and same light switch ..... Principle is the same.

Aidan where are you?

My rear diff stopped lighting up a while back. I'm asuming it's not working as I can usually feel it on loose gravel. My front is working fine.

Should the rear knob just pull straight without twisting? I've completely forgot how it works and I though it was broke because it wasn't twisting?!

After changing my starter motor last weekend, I had a chance to look at the rear diff actuator. I manualy pulled the pin in and out (red gaitor), it seemed stiff but it did move ok.

[Mickyfin]

Yes, pull straight out, its not like the front one.