FredR

When I drive over those small but sharp speed bumps in the road my PSD alarm lights up. It seems to reset immediately but it is a bit annoying.

Wondered if the brains trust have any suggestions as to what the weak link may be. I am guessing it might be the connector at the PSD unit but...?

I hope to carry out the PSD flush procedure in the next day or two so thought it might be useful if I can identify/resolve this issuebeofre I make anything worse.

Rgds

Fred

worf928

Red? As in the warning? Not the green as in 'Operating?'

If the former, is it preceeded by an ABS warning?

FredR

Dave,

The red alarm lights up when traversing this type of bump which gives a rather sharp jolt- no ABS warning and the light goes out immediately- I think it illuminates as the rear wheels hit the obstacle.

The green light shows when the PSD is actually doing something and that seems to work just fine.

Rgds

Fred

Randy V

Loose/oxidized connections on the PSD pump. Very common and relatively easy to fix after removing the wheel well liner - assuming yours doesn't crumble to dust just by looking at it.

Bigfoot928

also metal shavings stuck to the abs sensors....

928Myles

Given that there is no ABS warning my guess would be dodgy sensor in the PSD control unit (under the drivers seat IIRC).

Myles

FredR

That is a interesting comment. I recently had the front discs off for the first time in 10 years for a general check/clean up and I was surprised at what I saw on the ABS sensor- as per your comment a lot of magnetic swarf. I cleaned it up in-situ best I could not wanting to remove the thing for fear of it falling to pieces in the process. I figured that if it was not working correctly I would get an ABS warning that to date has never happened.

That being said I as I understand the PSD system responds to input from the rear ABS signals and the accelerometer under the passenger seat and outputs and signal proportional to the computed need to give a variable amount of lock-up. My assumption is that if there is a problem with the rear ABS signal then again I would see an ABS alarm initially. I had the rear discs off last year and the rear sensors looked clean.

For sure I will take a look at the PSD pump connector. Last time I pulled the rear splash guard it was fine but that was some years ago - just about everything plasticy in the engine bay is falling to pieces or has been replaced. Ironically the front wheel arch shield is still in great condition- let's hope the rear one does not fall to pieces unless Randy has put the mockers on it!

Thanks for the inputs to date- will post some pics as I inspect and change the PSD fluid.

Rgds

Fred

Dave928S

I'd also wonder about the accelerometer, considering it's a bump sensitive issue, but some other wiring/fuse/relay worth checking would be in the spare wheel well, which is for the PSD. Go crazy with the deoxit on every connection just to be sure.

FredR

I'd be delighted to if I could get hold of some!

Trouble is nowadays so many things are banned from being carried by air cargo couriers- the list just seems to grow daily and if they suspect anything it simply does not go. Aerosols- no chance, batteries- no chance, any chemical that can vaguely be used for nefarious activities or is volatile- no chance. To be fair not sure where deoxit fits in the scheme of things.

On the positive side although many of my wiring cables, connectors and plastics are suffering to varying degrees, inspection of terminals usually reveals them to be quite bright.

I have searched town to see if deoxit is available but no joy so far- perhaps there is some other equivalent that can do an acceptable job? I should be able to find something here. If I know hwo makes it I can usally trace such through the main agents. Trouble is being a relatively small place, such outlets tend to be stuffed away where you least expect them.

Rgds

Fred

Dave928S

I could send you some if we can work out what would get through. I suspect the aerosols wouldn't get through, but the small bottles of liquid might.

Left to right ... bottles of 100% liquid ... small 100% aerosols ... large 5% aerosol

Made by CAIG Laboratories in the US .... http://store.caig.com/s.nl/sc.15/cat....SS/SS.5933/.f

worf928

No ABS warning means that no component that can cause an ABS code (e.g. sensors, wiring to ECU from sensors, etc) is a top suspect. Failure diagnosis should start with components that are exclusive to PSD.

As others have mentioned above:
- accelerometer mounting or connections
- psd fuse and relay in spare tire area
- connections in vicinity of pump and accumulator

Also:
- PSD/ABS control unit connector pins
- pins on junctions of the PSD/ABS harness (there is at least one junction for the harness under the dash. Might be more. Wiring diagrams for all years not memorized.)

worf928

Note that the control unit for PSD is also the control unit for ABS.

It is located (on LHD 928s) in the far upper outboard corner of the driver-side foot well. (Exactly: the hardest spot to get to in the foot well.)

FredR

Dave [Worf] - thanks for the inputs- I understood the control unit is integral with the ABS and yes- it is a bit of bugger to access that thing- hopefully I will not need to play around with it as I suspect the problem is at the back of the car seemingly triggered when the rear wheels cross over the mini speed bumps.

Dave [Aussie],

Thanks for the offer- much appreciated. My problem is not ordering stuff as I have couriers available to me in many countries- it is question of understanding what they will allow hazard wise and I do not know what liquid[s] are in the deoxit bottle and doubtless no one will tell you that - I suspect it is likely something quite volatile and for liquids like that if in doubt it does not go and that before Donald Dump was elected!

A friend thinks he may be able to get me a can of something made by Wurth [German outfit]- should know tomorrow.

Apologies- never mastered the "multi quote" technique.

Regards/many thanks

Fred

Dave928S

Fred ... Deoxit products are widely available here at electronics supply outlets, which is where I get the small packs shown. I get the large aerosol from the distributor, as it's not stocked anywhere I could track down. I actually got a box of the large cans and introduced quite a few auto electricians and mechanics to it.

I did a bit of googling and it seems that some Deoxit electronics products (such as their fader contact cleaner) are available in your part of the world, so electronics parts or repair outlets might be worth a try.

FredR

Dave,

I previously tried to track some down up in Dubai as I have an Aussie friend up there who does their 928's but no joy so far.

No problem getting a contact cleaner but they do not get rid of any oxidation products [As I understand] which is where the DEoxit "shines" of course.

Regards

Fred