Suspension Ecu?, Where?

I had a (very) quick look for the suspension ecu the other day. When I lifted the plastic cover on the brain box (the car's not mine) I could see three in there. Presumably one for suspension, one for engine management. What is the third one? And out of all of them which is the suspension one. I want to check me mosfets to see if they need surgery.

Hi Dave,

The third one is your ABS.

The Suspension ecu is the one with Valeo on it. Its usually bolted to the engine ecu. The suspension ecu has a white and a black connector with a thick bundle of cables attached to each.

cheers

noz

Hi demag

The suspension ECU is slightly smaller than the other two and the case is an aluminum casting. As Noz says it is the only one with two separate electrical connectors. You should also find H4 marked on it.

Regards

XMexc

Thanks both will look over the weekend if the rain holds off.

I had a good day today. Not only did I start replacing the heater plugs but I removed the suspension ecu as well!

The markings on the case are:- 73811502; 9623191980; 12v; H4.3; S212C The last letter in that sequence is a "C" I think, but it could be "G" or maybe "0" its just not very clear. Also "13/95" which I assume is the build date.

The circuit board is marked "VALEO SUP CUIVRE 4.3" and "NSAE 44/94" which I would imagine is the assembly date.

It looks like the VN05N has had its chips ( ) Its the left one next to the white connector block, but the right one looks ok. Looking at Norrie's pdf file comparing his picture and my card the pc tracks look different in that area. I have some resistors to solder on but I'm not 100% certain of the exact position. I'll try and upload a photo later. Were there variations in the card design? I assume I have to solder them to the four large solder blocks but I'll wait for confirmation of that.

Just out of interest the car seems more bouncy now at the back.

This post has been edited by demag on January 29, 2007 08:02 pm

Hi Demag,

you are in the same position as me then trying improve the occasion hard ride. I have removed the electronics and am armed with the bits to solder on. I too have found the ride to be more bouncy but harder - certainly not smooth which suggests the computer was at least doing something. No signs of damage or heat on the VN05N though.

I'm following another topic also which is investiagting the electrovalve itself and potential seal failure. It seems a few of us are checking the same things.

BTW which diodes do you have? I have purchased from maplins both 1N4007G & 1N4007S, the difference seemingly glass pasivated vs silicon?

cheers
Gav

I have not personally ever had a problem with the suspension computer, but a sure way to test whether it is working or not is to pull the plugs, if it makes no difference its not working! ...Assuming of course all your spheres are not flat!

Peter.N.

Got mine from Maplins Gav. They only had the one type in stock, can't remember which The cheaper of the two, although there's only coppers in it.

I don't think there's much left in my spheres Peter but the one mosfet doesn't look well at all . I thought I'd read somewhere that if one mosfet packs up the circuits shut down so as not to compromise the handling of the car, in which case I would have thought removing the ecu would make no difference. But it does feel more joggly at the back.

Here's a piccie.

Is it the large square solder blobs in the middle of the picture where I connect the diodes across?

This post has been edited by demag on January 30, 2007 01:43 am

Hi demag,

Here's the 'How to' file with pictures which should answer your question.

http://club-xm.com/forum/index.php?showtopic=845

And another picture to help identify the exact contact pads and diode orientation:

cheers

noz

Hi noz,

Thanks for that info however I am totally at a loss now as every photo I look at is a different card to mine. Although the pictures are extremely clear and it would be straightforward copying them on an identical card. Mine is different and I don't want to run the risk of screwing the whole card by soldering the diodes in the wrong place.

I am considering repairing the card but leaving the diodes off a la Citroen. Presumably they last a few years before failing. Unless I can get precise details for my card. I wonder how many variations there were?

Dave,

The MOSFETs will simply shut down (protection circuit) and you won't get the benefit of the repair you've done if the diodes in the electrovalves have blown. Eventually the MOSFETs will burn out again without replacement diodes.

As a general rule the repair is better tackled the other way round - i.e. replace the diodes first. If one (or both) of them have blown they may not yet have fried the MOSFET(s) - although with blown diodes they will have shut down (protection circuit). If the MOSFET(s) aren't fried they will work correctly if the diodes are replaced. (Having said that - in your case it seems clear from your photo that you had one fried MOSFET). For many people simply replacing the diodes can transform the car (assuming the spheres / LHM / filter etc are in good condition).

(Even if the diodes in the electrovalves haven't blown - it's a good idea to add new ones into the circuit - they won't do any harm and should prevent the problem arising in the first place.)**

The photo showing 3 MOSFETs is from a Xantia Activa I think - hence the third "CAR" circuit.

You should find it a lot easier to connect the diodes to the loom going into the ECU. Remove the connector that's attached to the white socket on the ECU and see if you can identify the following wires (Option 1 should be correct for the RP of your car):

Option 1

A. External Dia 2.7mm - Yellow/Brown (1 wire)
B. External Dia 2.7mm - Yellow/Red (1 wire)
C. External Dia 3.3mm - Blue & Blue (2 wires)

Option 2

A. External Dia 2.7mm - Yellow/18 (1 wire)
B. External Dia 2.7mm - Yellow/3 (1 wire)
C. External Dia 3.3mm - Blue/15 & Blue/4 (2 wires)

Option 3

A. External Dia 2.7mm - Green/18 (1 wire)
B. External Dia 2.7mm - Green/3 (1 wire)
C. External Dia 3.3mm - Green/Yellow/15 & Green/Yellow/4 (2 wires)

Option 1 is for earlier XM Hydractive II cars (RP 6383 on) through to Option 3 for the late models. These are the only three wiring options I have found (covering RP6383 to RP6947 and RP7483 to RP7847) - there may be variations, particularly outside these RP ranges.

A. = Rear Electrovalve
B. = Front Electrovalve
C. = Common Earth Wires

The marked end of the diodes should be connected to A & B respectively. The other end of the diodes should be connected to either of the common earth wires C.

If you want to go down this route you can find the wiring diagrams in Noz's CD manual (starting at section 580-1/20 - also check the beginning of that chapter for useful information). Be sure you identify the correct wiring for your car.

(Blatant plug) **I have a ready made fixing kit for this that takes less than 5 minutes to fit and doesn't require any soldering. If anyone else is considering this job I also have a good supply of the original VN05N MOSFETs, 1N4007 diodes and some repaired ECU's available - PM me for details.

Thanks to Noz, Techmanagain and others for pointing me in the right direction in the first place.

I hope this helps.

Roy

This post has been edited by mackay1 on January 31, 2007 05:40 am

Thanks for that info Roy. That's brilliant. You're a dark horse aren't you all this gear and no one knew .

I think in my case the cable route will be a lot safer so that's what I'll look at. I have the diodes already and the mosfets are on order from RS although they list them as extra range items with 5-10 day delivery.

The back is definitely harder now so I think it was working. I think the front mosfet is fritzed as you say. Yes of course if I put a new mosfet on it will fry again because of the duff diodes. Derrrr!

Interesting but when I stop the car now the back drops. It didn't do that before. Is the anti sink tied into this circuit?

Hi Demag

I would be interested to know the RS part Number for the devices you have on order?
When I checked a year or so ago RS had discontinued the 5 leg solid state switches made by ST that are fitted to the Mk2 ECU's. They did still supply a 3 pin MOSFET with a very similar part number.

Regards

XMexc

Hi Demaq,

I'm in awe of people like Mackay1, Noz and XMexclusive with their electronics knowledge, but as far as antisink is concerned there is no electrical hookup, it's purely pressure operated and is virtually foolproof.

From your description you must have an internal leak, a rear suspension cylinder is probably favourite. Suggest you check the return lines at the tank (reservoir) to see if one is showing flow as your rear end settles.

Derek