Citroen XM Forum

Automatic Suspension message - If you put the slide witch to Sport, does that stop such messages appearing randomly?
IIRC, the LH display is looking (while driving, as opposed to start-up) for a change of the selected suspension mode, which suggests that the Auto signal to it disappears then re-appears, the latter triggering the message.

Check wiring/connectors between mode switch and LH display?

I think that the suspension mode is the lowest priority message for the display, so if a higher priority message is flashed up (however briefly), the suspension message will be displayed afterwards, so it could be any other message being briefly triggered.

Hi John,

Blower circuit . . . This is the earliest circuit I have which shows a digital display:
644-2/10
Sorry, not a good (Pepon) scan; the pdf above might be better.

xantia_v6 wrote:I think that the suspension mode is the lowest priority message for the display, so if a higher priority message is flashed up (however briefly), the suspension message will be displayed afterwards, so it could be any other message being briefly triggered.

It doesn't do that. Only the message relevant to the error flashes up, none other.

No other messages appear whilst driving, just the Automatic suspension message and only when the tacho is going nutty. It goes into SPORT via the switch and shows the correct message.
If the TDC sensor signal goes straight to the Tacho, it cant be effecting the suspension could it?

If the suspension is selecting the sport mode it won't display any message. The message is only visible when the switch is used to select the sport option.
I suspect you have a wiring fault, possibly a chafed wire causing random shorts to Gnd.

Removing the dash skin is actually pretty straightforward and unless other reasons can be found, could well be worth it.
The skin unbolts from the sub structure and the car is driveable without the skin installed.

Russ,

That is correct, a message showing suspension setting is only displayed when you manually select it (slide switch), not during normal driving.

I was wondering, though, whether if you manually select Sport mode and leave it there, any messages pop up while driving (and the tacho going loopy). My reasoning is if a manual selection of Automatic mode (made whilst driving about in Sport mode) is the only way to legitimately get the Auto message to display, then this might be happening 'accidentally', due to a poor switch/wiring/connector.

Diagram below is for Hydractive I:
Open in Word.

This shows the Suspension Mode switch #606 which simply connects pin14 to pin15 on the suspension ECU (#143) 15-way black connector.
When switch is Open, suspension is in Auto mode
When switch is Closed, suspension is in Sport mode
The 'common' side of the switch makes a feed to the LH matrix #30... 15-way Blue connector, pin10

The Mode switch obviously isn't getting stuck 'closed', or you'd be going into Sport mode AND the dash Sport light would illuminate.
Presume the switch itself is ok - i.e. it brings the dash Sport light on.

My guess is that if the feed to pin10 of the display is faulty, then the display might show Auto, and do this each time a fault in the connection occurs.

______

"If the TDC sensor signal goes straight to the Tacho, it can't be affecting the suspension could it?"
No. Engine speed is one of the few things not fed to the suspension ECU!

C.

Hi Russ

What are the codes marked on the suspension ECU fitted to your car?
Have you swapped the ECU?
Do you still have the one from your old car?
If so add the details from that.
HA2, HA2B or HA3.

John

Good, so there isn't a relationship to the TDC sensor and suspension. Or at least a common feed.

A clue. The tacho flicks about as well with the ignition on. Now with my awful understanding of any thing electrical! ... If the engine isn't rotating, it can't feed a signal to the tacho ...or is there a power feed to it?
It would make sense what Will is suggesting about a wire shorting to ground. As it doesn't always flick about. But it does seem to be getting worse.


I think you might also be right Chris about the feed to pin 10 on the dash plug. If it is faulty then it would make sense that it pops up that message. Its almost like it gets reset into thinking it's back into automatic mode. As I have said before, only that message pops up. It never goes into sport by itself, and correctly brings up the light and sport mode message when the switch is put into sport.
I will try it in sport mode and see if it triggers any messages.

John, I do still have the suspension ECU from the old car. I'll get the code.

With the blower, I have replaced it with my old unit. See what happens there. As of this afternoon it was working fine up through the different fan speeds.

Developments.

Firstly.... John it's an H3 ECU. I have fished out the spare from the loft and it has H3 on it. Considering the two cars were built days apart, I can't see them being different.

I took it for a drive round town just now. On start up waiting for glow plugs ect, the dot matrix woke up, did its screen swipe thing and then went dead. Started it up as normal, no press the brake pedal message. Warning light with the exclamation mark on central display was lit. But crucially no auto or sport messages.

Drove quite away in sport mode, and it very briefly came up with sport mode message. As soon as it appeared it was gone.
I popped it into auto mode and nothing. Left it and through out my drive, it popped up 8 times. All this with the tacho needle fluttering about. Interestingly with the message up, and it can stay on for a quite a while at times, the tacho needle is fine.
Suspension noticeably going in and out of sport mode when switched , as normal.

Anyway eventually everything sorted itself out. I noticed the tacho needle was fine. Popped it into sport, message came up as normal. Put it into auto. Auto message came up as normal. None reappeared in the rest of the drive. Tacho behaving all that time, but it did flick a tiny amount when idling at traffic lights.
And that is how I left the car! Pretty much everything behaving. It won't last! ....It's done this before.

The blower is blowing on all speeds and it warms up on the different settings. It didn't stop working or go to default mode of only working on full blast. So see how that one goes.