[928uk] PSD question

[James Musson]

Okay, great. Thanks for the advice. I'll have a listen and see if I can find someone with a diagnostic tester.

The alternative is to buy a tester - might be a worthwhile investment in the long run. It seems like options are a little limited nowadays with many being NLA. Does anyone have a current recommendation?

I can see:

Durametric (enthusiast or pro)
https://m.gendan.co.uk/product_DURAENTH2.html

UDT999
http://www.928-ecu-repair.com/diagnosetools_udt999.html

SharkTuner
https://sharktuner.com/

Also saw this on eBay:
https://www.ebay.co.uk/itm/204426241912<https://www.ebay.co.uk/itm/204426241912?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=JuwjRpUvRgS&sssrc=4429486&ssuid=z8yvYMBzR-m&var=&widget_ver=artemis&media=COPY>

Thanks

James

________________________________
From: Paul R Smith <smiffypr at gmail.com>
Sent: Friday, December 29, 2023 9:35:16 am
To: James Musson <james_musson at hotmail.com>; 928uk at lists.928.org.uk <928uk at lists.928.org.uk>
Subject: Re: [928uk] PSD question

Which is why you should listen for the pump running and stopping. If the pressure has dropped, the pump will run to build up the pressure then stop after a few seconds. If the pump runs and doesn't build up pressure it would run until the ecu decides there's a fault, and that doesn't appear to be happening, but listen anyway, then decide if you need to pull the fuse.

You ought to prioritise finding someone with a Bosch "hammer" or JDS "spanner" to read the fault codes, maybe someone else who is going to Brooklands has one?

Without the fault code you will be just guessing and you will waste a lot of time or money.

GUESSING: if the pressure is there, then the ecu activates, there is a solenoid valve that allows the pressure through to the slave cylinder on the diff, so it could be the solenoid, or the system needs bleeding, or leaking, then the hydraulics need to activate the actual locking plates, so there could be a mechanical issue (including wear), then the system recognises that the wheel speeds are getting closer and it knows that things are working. So there are lots of possible points of failure.

Smiffy

On 29/12/2023 09:19, James Musson wrote:
Thanks for the reply. So far, the warning has only come on when the unit should actually be doing something, i.e. when the rear wheels are slipping and the green PSD light is on. Unfortunately, I don't have anything to read the fault codes with :-(

>From what you are saying, though, it sounds like the system will protect itself from further damage so there's no need to pull the fuse? The reason I asked was because there are stories around of the pump motor coils burning out and I would like to avoid that if it hasn't already happened.

Thanks

James
________________________________
From: 928uk <928uk-bounces at lists.928.org.uk><mailto:928uk-bounces at lists.928.org.uk> on behalf of Paul R Smith via 928uk <928uk at lists.928.org.uk><mailto:928uk at lists.928.org.uk>
Sent: Friday, December 29, 2023 9:05:19 AM
To: 928uk at lists.928.org.uk<mailto:928uk at lists.928.org.uk> <928uk at lists.928.org.uk><mailto:928uk at lists.928.org.uk>
Subject: Re: [928uk] PSD question

If the system detects a fault it will shut down, so the pump should not
run continuously.
It is located in the left rear wheel arch, behind the left rear wheel.
Have a listen around there when the ignition is turned on. If the pump
runs for a while then turns off, see when the warning comes on, that
might give a clue, e.g. if it fails to achieve pressure, recognises a
fault, shuts off the pump and brings up the warning.
But, I would strongly advise you to read out the fault codes before
diving in and flushing it.

Smiffy

On 29/12/2023 08:54, James Musson via 928uk wrote:
> Hi all
>
> I have the 'Differential Control Off' message showing on my '95 GTS when the green PSD light is active (and the diff should be locking). There's quite a lot of info on the 'net about this condition and I am (perhaps foolishly) hoping that the system just needs flushing, given that I can see any record of that being done in the recent service history. I don't have time to do that, or get someone else to, right now but I wanted to drive the car to Brooklands on New Year's Day.
>
> So, my question is: should I pull the fuse from the PSD pump to avoid further damage and keep on driving it? And a follow up question: where is it? >From the photos I have seen it looks like the PSD assembly is accessed from the boot well somewhere but I have never noticed it before.
>
> Thanks!
>
> James