Suspension Ecu Not Getting Power

[David Hallworth]

Hi Guys,

The Hydractive ECU (H5) on my XM isn't getting any power.

I have checked the fuse that is mentioned in the handbook and Ciaran has also advised me to check the ones that act on the deadlock as this caused problems with his suspension also.

After checking the two of these I am not getting any power at all to the ECU.

I have remade all of the earth clamps that go to the inner wing also just incase it was one of those that was causing problems.

I just wondered if anybody else had experienced any problems similar to this and could advise me where to check next?

If it makes any difference it is a 1998 V6 Exclusive.

Regards

David.

[xmexclusive]

Hi David

The suspension ECU has three fused feeds, four if you count the feed to the suspension switch. There are also at least double that number of earth points. If you put up the ORG I will try to look out the actual wiring diagram.

On the early Mk2's the wiring comprises:

F10 supplies the suspension switch lighting but the interest here is that the earth side of the switch also earths pins 12 (suspension switch contact) & 14 (hard mode dash indicator) of the suspension ECU.

F34 supplies pin 1 & 2 of the suspension ECU and this supply is permanent/unswitched.

F23 is an ignition switched supply (live when switched to M&D positions) to the distance sensor which then sends its signal to pin 11 of the suspension ECU.

F7 is an ignition switched supply (live when switched to M position) which is the main ECU supply (pin 5) but also supplies the body movement sensor.

The suspension ECU main earths are pins 8 and 15. This earth is also the earth for both electrovalves and the brake pressure switch.

Pin 6 of the ECU is earthed via the boot lighting switch and pin 7 via the four door switches.

It would not have made sense for Citroen to change the suspension ECU pins during the MK2 production run but as with all XM matters assuming common sense was applied can waste a lot of time.

Regards

John

[David Hallworth]

Hi John,

Thanks very much for your help again.

The RP is 7704.

Will check those fuses tonight.

Another suggestion is to look for a while connector either under the glovebox or under the steering column as apparently this provides the ECU with power also.

D

[xmexclusive]

Hi David

Have checked against the diagram for your ORG - the only difference I could see was that the F23 feed had been moved to F19. All the fused feeds have a single connection between the fuse and the ECU. Most are plug 18B except the F19 feed that is plug 13B. I suspect that the 18B plug is under the dash drivers side where the cables go through the front bulkhead. Not usually a problem area for connectors. I would not envy you trying to get under the passenger air bag to check connections. My guess is that plug 13B is a white 3 pin connector under the LHM tank.

Regards

John

This post has been edited by xmexclusive on August 14, 2008 11:17 am

[David Hallworth]

Thanks John.

I'll head out and check the rest of the fuses mentioned either tonight or tomorrow.

I am just trying to do a few jobs on it to get it ready for MOT now.

The strut tops on it don't look as healthy as some i have seen so i want to ensure the suspension is nice n soft rather then hard. Have replaced the spheres also, probably find the old ones were fine anyway!

David.

[David Hallworth]

Don't suppose anyone has a owners manual for a series 2 handy do they?

My car is missing fuse 8 at the moment but as we have the decorators in I can't find my handbook anywhere.

Thanks in Advance

David.

[xmexclusive]

Hi David

F8 is one of the three Dot Matrix Language selection fuses. Needs to be missing for English. Put it back in and you will get French.

Regards

John

[David Hallworth]

Ahh,

Guessing I don't want that fuse in then!

I have absolutely no idea why it isn't getting power now.

Every fuse that has been mentioned has been checked, guess its down to just checking multi plugs and stuff now.

David.

[xmexclusive]

Hi David

You could check for the feeds and earths at the ECU plug with a meter. You then stand a chance of knowing which one is missing.

Regards

John

[David Hallworth]

Thanks John,

Will give it a go in daylight tomorrow.

Electrical faults have never been a strong point of mine.

D

[xmexclusive]

Hi David

Best of luck with your fault finding.
The ECU plugs are not that easy to read the pin numbers on or even work on with a meter. I put some recovered plugs in a corner somewhere a while ago and intended to make up break-out connectors so I could check ECU wires easily. Must look them out and get on with it. Do not forget that some of the ECU feeds are only live with the ignition switch in certain positions. I spent ages the other day looking unsuccessfully for an intermittant dipped headlight wiring fault only to realise later that you need the engine running for the feeds to be live and that my dead wire was meant to be dead in that state. Turned out to be an earth fault anyway.

Regards

John

[Jan-hendrik]

Use a magnifying lens to read the pin numbers. Once you see the sequence it isn't hard, or just make a note of them.
Piercing the wires to be checked with the connectors in situ with a sharp needle makes it easy to check for voltage present. There are special probes for that too. Hope you find the problem

[David Hallworth]

Have finally got round to doing some fault finding.

What i have found:

No 12v feed to the ECU

Continuity between Pins 1 + 2 on black connector

12v feed getting to fuse 34 but no continuity between fuse 34 and pins 1 and 2 on Black ECU Plug

12v feed getting to fuse 23 with ignition on.

With a very brief 12v splash across white plug pin 1 the front E-Valve opens and with a brief splash across pin 2 the rear E-Valve opens.

Need to try and find where there's a break in the cable between the fuse and the ECU now.

Thanks again for your help guys.

David.

[David Hallworth]

Have been advised that this could be caused by a high resistance at the loom connector, possibly being caused by corrosion.

Does anyone have any idea where this is located?

Thanks

David.

[David Hallworth]

FIXED!!

I removed the LHM reservoir and cleaned all of the plugs under there then noticed the ones I was cleaning had a plastic sheath around them and the suspension ECU harness had a material like sheath around it.

I got a torch and followed it back under the water reservoir through the bulkhead on the drivers side. I then started looking under the dash by the drivers feet to find 3 plugs. 2 smaller grey ones and one big white plastic one.

I took the 2 grey ones out one by one n cleaned them, as i was removing the 2nd one the 3rd big white one fell out. I sprayed it with contact cleaner and plugged it back in and sliding the locking clasp over it. As i did this I immediately heard the electrovalves open and buzz.

I put everything back together and took the car for a run, it has its magic carpet ride back again. Think it needs a drop link as there's a bit of noise but apart from that its lovely n smooth again.

Thanks for your help in previous posts guys.

Regards

David.