Electrical Gremlins

[nightmare]

Hi,

New here, but have had an XM 2.5TD since 2008.

I've got a problem

The other day I turned the ignition OFF and the engine carried on running ( had to stall it), with the engine stopped and ignition OFF the dash lights continued to stay illuminated.

After about 45 secs they went out.

Turned ignition ON/OFF a couple of times and everything seemed to be O.K.

Started car.
O.K. to begin then all dash lights/guages stopped working

switched OFF. (engine stopped).

Checked fuses O.K.

Checked supply to various dash guages/dot matrix & clock.(Power at fuses & at wiring terminals to the dash & warning lights/guages).

The next day the BATTERY was completely dead.

Removed and charged fully.

Now when I connect the battery the following happens:-

(1),Engine cooling fans on full
All dash/warning lights( apart from batt & glow plug) illuminate.
fuel guage, oil level guage working.
Alarm operating( cannot disarm)

When the ignition is turned on :-

(2),Engine cooling fans STOP
Batt & glow plug lights illuminate.

Car won't start (turns over).

I disconnected/removed the ignition switch and when I reconnected the battery
it was the same (see (1)).

Please HELP

[xmexclusive]

Check out the double injection relay.
On the front of the ECU box drivers side of engine bay.
Usually brown or black marked Bitron type 240.104 more than twice as long as a standard relay. Has 15 pin plug.
Clean the contacts and retry.

If it is a late 2.5 then the alarm has no isolation switch which is a pain.
Fans running on likely to continue rather than time out.
This flattens the battery overnight.
Temporary workaround is to release the bonnet, lock the car up then disconect one of the battery leads.
Saves having to change/recharge the battery every morning.

John

[nightmare]

Hi John,

RP/ORGA 6679 YM 1995

It has the isolator switch in engine bay behind the O/S headlight and it IS turned OFF.
I was under the impression that this just turned the siren off/on.

Have cleaned the bitron relay and now I can cancel the alarm with the dash switch.

Still have :-

Engine cooling fans

ABS,brake pad,stop,rad level lights on. dot matrix working

And engine management light glows.

Oil level guage light, but no level is indicated.

As soon as battery is connected. These light are constantly on.


When the ignition switch is turned to the run position the Engine cooling fans STOP and the glow plug light lites up as normal.


Have disabled cooling fans by removing relay behind N/S headlight for the moment.

My main problem is that the power is not being isolated even with the ignition switch disconnected/removed.

Any idea where to look next?

Keith

This post has been edited by nightmare on January 29, 2012 02:57 pm

[nightmare]

Hi John,

From reading in a previous post 10 July 2010 you had similar problems with a silver 2.5 estate.

Did you fix it ?

If so how?

Keith

[xmexclusive]

Hi Keith

I would be inclined to try a spare ignition switch next.

The silver XM that I posted about still has problems.
I had found a way to get a green on the immobiliser.
That got it running.
Usually it behaves.
Occasionally it christmas trees the dash lights.
Once in a while it ignores the ignition switch and runs on.
The cooling fans will often run on so I usually pull the battery lead off overnight.
Glow plug light is on all the time but the plugs do not heat.
Makes starting a pain if it freezes overnight.
Not my main XM, just using it as a van for now.
Sometime soon a couple of my 2.5's are going to be stripped for spares.
Still deciding if this silver one goes SORN and gets rebuilt or becomes a donor.

John

[nightmare]

Hi John,

Not sure how it can be the ignition switch as the simptoms are the same with it removed.
I.e. lights and fans still on

Still, some progress in that the alarm is now sorted and I.ve had it running last night.
Dash behaves itself untill REVERSE is selected, then the oil level operatesand the tacho stops + some of the dash lights dim a bit.

But it does start and stop O.K.

Could it be an earthing fualt?

Keith

[xmexclusive]

Hi Keith

I suspect the wiring loom across the top of the front subframe.
Lot of corrosion here usually but the leaking anti-freeze can also attack wiring insulation.

Not going in to follow this up this time of year on mine unless I have no choice.

The XM ignition switch is an easy electrical check and partial failure a common fault.
Failure can give all sorts of odd results including electrical feeds after switch off.
Just plug in the replacement switch to the 3 connectors not physically install the switch.

John

This post has been edited by xmexclusive on January 31, 2012 12:13 pm

[Sharo]

Hi nightmare
I've had similar problem when a diode in the alternator had become shorted. Try to unplug the thin wire from the alternator and see what happens. Also is it possible this XM to be with BSI (Multiplexee in france)?

[nightmare]

Hi Sharo,

When it stops RAINING I'll give it a try.

NO it's not multiplexed luckily or diagnostics would REALLY be difficult.

As if it's ever easy.

[nightmare]

UPDATE

Have changed ignition switch
Have chacked alternator OK
Have checked wiring across front OK
Have checked and changed relays on slam panel
Have checked and changed engine bay fuse box
Have checked and changed main fuse box No change apart from now able to select language for dot matrix

Have found that fuse 34 when removed stops cooling fans and warning lights/guages.
The strange thing is that fuse 34 is supposed to protect the central locking,plip,alarm and hydractive suspension.

With 34 removed the central locking and alarm still work with the plip.

Any help appreciated as I want to use the XM for the ICCCR.

[noz]

Hi nightmare,

I appreciate that you listed the symptoms back in January. However you have obviously done a lot of work since then. Have the list of symptoms changed any or are they still the same as you listed back in January?

Diagnosing electrical faults remotely is always very difficult. Because you can't see or hear the car you miss the little tell-tale signs which would lead you to an answer. Therefore, in the abscence of seeing the car first hand, an accurate description of the symptoms no matter how trivial will be the best way to try to help you remotely.

If you are prepared to list the symptoms in detail I will study the wiring diagram and try to discover where the short circuit is occurring. Could you please list the things that seem to work and don't seem to work in each of the positions of the ignition switch?

Cheers

noz

[nightmare]

O.K. Noz,

Symptoms as follows

With fuse 34 inserted, ignition switch off.

Dash warning lights illuminated
Engine check light glows faintly
Dot matrix works
Radiator cooling fans full on high speed
=============================
Fuse 34 inserted, ignition switch to acc.

Dash warning lights OFF
Engine check light OFF
Dot matrix works
Radiator cooling fans OFF.
=============================
Fuse 34 inserted, ignition switch to ON/RUN.

Dash warning lights ON
Engine check light ON
ABS light ON
Glow plug light ON for normal amount of time
Oil level guage WORKING
Dot matrix Works
Radiator cooling fans OFF.
=============================
START ENGINE, Fuse 34 inserted.

Dash warning lights OFF
Engine check light OFF
ABS light OFF
Oil level guage stops registering as normal
Dot matrix Works
Radiator cooling fans OFF
REV counter,FUEL guage,TEMP guage WORKING.
Radiator cooling fans operate as normal when engine gets up to TEMP then cut out as normal.
============================
Select REVERSE

REV counter,FUEL guage,TEMP guage STOP WORKING
OIL level guage TRIGGERED
Parking brake warning light DIMMS
============================
Fuse 34 REMOVED, Engine running,

Dot matrix STOPS WORKING
REV counter,FUEL guage,TEMP guage NOT WORKING
Parking brake light OFF
============================
Fuse 34 removed,Ignition switch OFF
Engine STOPPED
Radiator cooling fans OFF
============================
Ignition KEY removed, Fuse 34 removed

Central locking/Deadlocking & alarm WORK using PLIP

==========================================

I hope you can make sense of that Noz.

Thanks in advance Keith(nightmare)

P.S.
I don't know if the speedo works with fuse 34 removed as I hav'nt driven it like that.

[nightmare]

Any luck Noz?

[Jan-hendrik]

QUOTE

Have found that fuse 34 when removed stops cooling fans and warning lights/guages.
The strange thing is that fuse 34 is supposed to protect the central locking,plip,alarm and hydractive suspension.

Fuse F34 on your model serves:

Water temperature control unit.
Central door locking control unit.
PLIP remote control unit.
Hydractive suspension system.
Alarm. Burglar alarm relay coil.
Burglar alarm warning lamp.

I may be wrong but I suspect the water temperature control unit is faulty. This could cause all kinds of gremlins.

There is another fuse that feeds instrument clusters: F23.

[nightmare]

UPDATE!!!

I have just found that if I unplug the grey connector on the alarm ECU( the grey TEXTON box).

ENGINE RUNNING
============
The guages stop working
The DOT MATRIX stops working
The dash warning lights stop working
HYDRACTIVE SUSPENSION working
Also Indexed rear view mirror stops working when reverse is selected.

IGNITION OFF
============

The DOT MATRIX not working
RADIATOR cooling fans STOPPED

I discovered this because I've got to the stage of disconnecting things one at a time to try and find the cause of my problems.

I'm getting desperate.

This post has been edited by nightmare on May 19, 2012 01:41 pm