UrS4 Diff lock

[HMS-S6]

Hi all, as you may know i bought unicom's S4. I seem to remember reading a thread (before i had mine) about a wiring modification to keep the diff lock from disengaging above the 25mph or so? Can anyone remember who posted it please? I NEED to do this to enjoy the snow when it arrives

[Zoig]

Look at the scheme a made for my car. Pin1 on Diff control module should be interesting.

Also I would advice you to add a secondary control lamp from the diff (the green dot witch lights up when the diff is engaged) to the instrument cluster (my car has free spot under ABS warning light, labeled ASR). Just because sometimes when i'm having fun I might forget to unlock the diff later on.

[sam80quattro]

cut the blue/white wires on 80/90 might be different for s4 though

[Zoig]

It's the White/Blue on the pin1. Just checked it from the Diff Lock control module.

Since the max height is 800px on attached images, I resized it to closer view.

[HMS-S6]

Thanks for the help guys. I take it i'm not the only one who has done this?

Am i right in thinking that the control unit is under the back seat?

[Zoig]

Am i right in thinking that the control unit is under the back seat?

As far as I know yes, under the rear seat.

Any guesses what would ABS/EDL do, if I lock the diff but keep ABS/EDL working? Any chance damaging the diff because of EDL?

Why I'm asking is because I'm planning to leave the ABS disconnect signal and speed signal disconnected on my UrS6 when it comes to installing the UrS4 diff.

[UrS4boy]

Any guesses what would ABS/EDL do, if I lock the diff but keep ABS/EDL working? Any chance damaging the diff because of EDL? Why I'm asking is because I'm planning to leave the ABS disconnect signal and speed signal disconnected on my UrS6 when it comes to installing the UrS4 diff.

The EDL system is based on having open front and rear differentials and then applying the brakes, through the ABS system to the wheel that is spinning. I believe that if you installed a UrS4 rear diff with the UrS4 switchable (vacuum-operated) rear diff lock, the EDL system would function just fine. It just would not have to work as much because the rear wheels would not spin as much when the UrS4 diff is "locked". That said, I have asked the question on my "home" forum, quattroworld, and will report back if the answer is different than the above.

[HMS-S6]

As far as I know yes, under the rear seat.

Any guesses what would ABS/EDL do, if I lock the diff but keep ABS/EDL working? Any chance damaging the diff because of EDL?

Why I'm asking is because I'm planning to leave the ABS disconnect signal and speed signal disconnected on my UrS6 when it comes to installing the UrS4 diff.

It might keep trying to apply the brakes on the wheel that is being forced to turn too fast due to the locked diff.

Why not put a switch in line for the feed to the ABS ecu?

[Zoig]

It might keep trying to apply the brakes on the wheel that is being forced to turn too fast due to the locked diff.

Why not put a switch in line for the feed to the ABS ecu?

I've heard that the EDL is not good to use with torsen rear diff (might kill it in the long run), but that's all i know about this. I was just wondering if the same applies to the fully locked diff.

I will install a extra switch for the ABS, I just want to keep the ABS and diff lock separate from each other. That's why I will install extra notification light into the cluster, because I might forget to check the diff status and end up doing highway speeds with locked rear.

Because the EDL should be replacement for locked diff (not very good at it). I'm planing on locking the rear diff and keeping the ABS/EDL on, so the EDL would help in the front and the good old locked diff in the rear. In theory this should be better than pure EDL or just locked rear and when the snow banks are higher than front numberplate, every small bit helps

UrS4boy, that's what I'm thinking, since there in no speed difference, EDL should do nothing. But on the other hand, what will it do in the rear, if its engaged because one of the front wheels is slipping trough or when the speed difference between front and rear is enough, would the EDL start to panic and try to equalize the speed between the diffs or just between the wheels on the same axle.
Let me know if there are some other thoughts in quattroworld.

[tellas]

hi guys, my s2 coupe diff light comes on when driving around 60mph intermittantly. need help.

[spink]

try changing the small black and white valve under the back seat.fixed the problem on a mates rs2,and only costs a few quid