Just to double check Roy. Are you saying this last mod of doing the diode repair on the back of the card is relevant to any variation of card using the same pin numbers? So in other words, wirdy or Gav could do it on their cards and me on mine using the same pin numbers even if the cards are different variations?

Did that make sense?

Thanks.

Hi Dave,

Yes that made sense. That's exactly what I'm saying - with one caveat. It applies to all the RP Numbers I've been able to check i.e. RP6383 to RP6947 and RP7483 to RP7847. [It applies equally to LHD & RHD cars and those with & without cruise control. These are the 4 main suspension loom variations given and I've checked all of them.]

It doesn't matter what colour the wiring loom is going into the white connector on the ECU, nor does it matter that the layout of the printed circuit board in the ECU may vary, the following always applies for those RP numbers:

Pin 1 - Connected to "Suspension electrovalve (single or front)"
Pin 2 - Connected to "Rear suspension electrovalve"
Pin 15 - Connected to Earth (common with pin 8)

In fact I'd be very surprised if this doesn't apply to the missing RP's as well - but I haven't been able to get hold of the corresponding wiring diagrams to check this - yet. I'm hopeful that I'll have that missing information early next week though.

When it comes to the wiring loom colours/numbering - again I'd be very surprised if there are any more than the three options (1, 2 & 3) I've already given - I just don't have enough information to be able to confirm this or say that option 1 changed to option 2 at RP6XXX and so on.

I've modified units outside the RP ranges given - and they have been consistent with a linear change from options 1 through to 3.

The information came from checking all the suspension wiring diagrams in Noz's CD - so anyone who's invested in one can verify this for themselves.

It makes things a lot easier doesn't it! Not just in terms of consistency but also because as an attachment point it's a much less vulnerable area of the board to be soldering. In addition you don't need to remove the board from the case in order to do the job (although having got that far you'd probably want to check the MOSFET's too).

Having said all that anyone reading this should think carefully before attempting this modification - these are sophisticated multi layer boards that are easily damaged unless you are proficient at soldering. The cost of replacement is likely to give you a heart attack - and some of the less common ones will be difficult to get second hand.

Cheers

Roy

Hi,

Just a big thankyou to everyone on the Forum

I finished repairing my suspension ecu over the weekend and refitted it today.

I now have two active electrovalves and suspension that moves!

I fitted the diodes on the back of the card as in Roys example. It took 5 minutes to do, although the mosfet was a bit more awkward. The tip on my soldering iron was a tight fit between the front pins to get to the back two. However I managed it and its working.

Its only in temporary at the mo as I have to re-silicone the case joints to keep the moisture out.

I'll post a couple of piccies in the next day or two.

I've only just realised but since I put the ecu back in, the back end hasn't dropped when parked

You couldn't make this stuff up could you?

I fitted one of Roys diode kits at the weekend (had it for a couple of weeks, and it kept raining whenever I was at home). So easy to fix. 15-20 mins, 1 pair of pliers needed, and now peace of mind that my VN05N's are safe.

Sticking my head on the ground and opening/closing the door I can clearly hear both buzzing away and clicking on/off so it sounds like I have done it in time.

I can definitely recommend his kit wether you currently have hard ride problems, or don't yet and want to avoid one common source of them.

Thanks Roy.

It took me quite a bit longer than expected - but I eventually managed to buy a complete set of XM Factory Manuals (MkI & MkII). With this I've been able to identify the correct wiring for any RP number and as a result have been able to make the fix kit more widely available.

Hydractive II was introduced in Feb 93 to LHD XM models from RP 5929 onwards and later to RHD XM's from RP 6383 onwards. I've now got accurate information from these RP's to the end of XM production. If anyone here needs the details for their XM - just PM me your RP No & LHD/RHD details and I'll send you the wiring details you need.

Those of you who've got one of Noz's CD's (the source of the original information posted here) may have noticed there are odd pages missing here and there and I hope to be able to fill in most if not all the gaps from the set of manuals I now have. I'll send these to Noz as soon as I can for inclusion in his masterwork. Meanwhile if anyone urgently needs access to any pages not included on his CD - please PM me details of the page numbers you need and I'll scan them and send you a copy.

Roy

I've just posted this information to another thread so thought I should update this one too.

The pin numbers 1, 2 & 15 given earlier are valid for Hydractive II ECU's fitted to all XM's from RP 6383 onwards.

Roy

Hi all,

I have just reinstalled my suspension ECU after having diodes installed as per Roys advice and guidance. I know that I'm not the first to say this but - the modification has made a world of difference. My 2.1Td has always been fiirm up front and lately has been riding like a rock. It now floats! I took the ECU circuit board to my local 'old school' TV repair guy and he charged me $10 (about 3 quid) including the diodes to do the job.

A special thanks to Roy for your help and advice.

Regards,
Kiwi

Hello

The addition of two diodes did also stabilize the hydraulics’ regulator in my
XM 2.1 TD orga 7834.


Thanks to the good advice and not least an instructive photo from Roy
The roads have suddenly improved.

Furthermore the sudden levelling two minutes after start has disappeared.


Best regards


Mich@el