Xantia XUD 1.9TD alarm suppression

lolingram · Post by **lolingram** » 25 Nov 2008, 11:25

Wife's XUD 1.9 Xant's alarm has somehow activated, and will not switch off with the ign key. Problem includes no pre-heat whilst activated, so I need a quick way to de-activate it ASAP. The car is fitted with immoboliser key key pad, but the inj pump has been castrated, so this poses no probelm.

HELP!!!!!! (please).

wheeler · Post by **wheeler** » 25 Nov 2008, 12:02

Removing fuse 17 should stop it in the meantime.
You may have water in the control unit underneath the left hand front seat, unplug this for a more pemanant fix if you dont mind loosing the alarm.

lolingram · Post by **lolingram** » 25 Nov 2008, 16:32

Removing fuse 17 should stop it in the meantime.
You may have water in the control unit underneath the left hand front seat, unplug this for a more pemanant fix if you dont mind loosing the alarm.

Thanks Wheeler; that's stopped the alarm just fine!

I now have (the original?) fault of no pre-heat. Any help in finding this item - plus any likely dope on a cure much appreciated. There is no current drain on switch-on as is usual, but feeding +12V to the preheat plugs results in an instant start.

Thanks again.

AndersDK · Post by **AndersDK** » 25 Nov 2008, 22:07

The diesel preheat timer is usually of a simple design : some electronics for basic timing, possibly some added electronics for temperature related modification of the timing period, a lamp & relay driver stage and a relay.

The common problem is dodgy (rusty) glowplug power cable connections to the relay contact terminals.
Once a smallish bad connection starts out, the connection heats up, and shortly thereafter you have a burnt out connection.
The amperage is pretty hefty - in the region of 10A each glow plug - total some 40A. This will over time at some point possibly burn out the realy contact points.
With a little smart fiddling it is pretty easy to move the relay control wires outside the timer box, and let it control an external standard power relay, rated at 40-50Amps in the contact set, leaving the original relay un-connected.

Very rarely the electronics circuit itself is bad.

You should have these connections on the timer box :

1) power input from battery to relay contact set
2) power output to glowplugs
3) earth for timer circuit
4) +12V ignition key feed for timer circuit
5) instrument glow plug lamp output
6) possibly a temp sensor input from an engine fitted temp sensor.

Happy fiddling

lolingram · Post by **lolingram** » 26 Nov 2008, 08:50

The diesel preheat timer is usually of a simple design : some electronics for basic timing, possibly some added electronics for temperature related modification of the timing period, a lamp & relay driver stage and a relay.

Thanks for the info Anders.... at the moment I am trying to locate the preheat device. Perhaps someone familiar with a late XUD (not HDi) Xant can help here. I can find NO fuse allocated to the device in the car handbook.

Post by **CitroJim** » 26 Nov 2008, 12:23

Hi Lol,

The glowplug controller is on the LH inner wing adjacent to the battery and well hidden.

Note that the controller is in turn controlled by the Engine ECU and if this is not happy, nor will the glowplug controller be. The usual problem is poor connections on the multi-pin plug on the controller itself.

I can post up the wiring diagram later if that will help.

EDIT: Here's the Wiring Diagram. The Glowplug controller is item 1150.

lolingram · Post by **lolingram** » 26 Nov 2008, 18:25

The glowplug controller is on the LH inner wing adjacent to the battery and well hidden.

Note that the controller is in turn controlled by the Engine ECU and if this is not happy, nor will the glowplug controller be. The usual problem is poor connections on the multi-pin plug on the controller itself.

Exactly the case Jim - or rather the pink wire going into the mult-pin plug simply severed; as in like bitten through, with all the strands still bright.... very strange. Soldered the ends together and alles gutes.

Thanks very much indeed.

Post by **CitroJim** » 26 Nov 2008, 18:34

Excellent

You've had a visit from a small rodent who has a particular liking for pink wires Lol...

Post by **myglaren** » 26 Nov 2008, 20:12

citrojim wrote:Excellent

You've had a visit from a small rodent who has a particular liking for pink wires Lol...

This isn't so strange as it may sound.

I read a couple of years ago* of some minor celebrity being away on holiday and the alarms/tracker in his Ferrari went off.
The police went to his house, gained entry to the garage, opened up the bonnet of the Ferrari and discovered a nest of rats in there munching away on the wiring.

Cost thousands to fix that little mess.

*BBC website IIRC