Citroen XM Forum

I note that as well as there appearing to be no power to the fuel system there is no power to the starter motor.
It's possible the Ign switch has failed internally, but this is two separate output circuits.
The Ign switch is fed power from a single feed from the fuse box.
A bit of diagnostic work is required before just changing parts.
A test lamp is all that's required.

Agree on a deeper diagnosis.

I will put the engine bay "on hold" for now I think and dig into the Ignition switch etc to establish why the starter/LEXIA are not working as they should.

With luck (on Lockdown/COVID), I will be getting a visit by a very clever man with an ELIT system in hand soon.

(Fuses all OK in the cabin and engine bay boards)

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How are the two supplies to #807 Injection Relay....
- permanent Batt+ to pins 15,8,14,11, via F31
- + to pin 2, via IGN sw

Cheers, will check these today and report back.

You will achieve more with a headlamp bulb than you will with any diagnostic appliance.
You need to load test the supply and Gnd circuits.

ELIT, Lexia and any other diagnostic equipment all read the same data...they are just graphical user interfaces...they display the data in an easy to read format...like Windows does to Dos...
Use a low wattage lamp and DMM for sensitive devices, a headlamp for high current devices and a scope for rapid signals, such as speed sensors and CAN information.

Pretty well all modern electronics is digital...On, or Off.

Noted on the need for bulbs, I will make up some kit to go alongside my Multi-Meter.

Electrics are my nightmare so please be kind to poor me .

A useful analogy for electricity is water: voltage = water pressure, current = flow rate.
Any connection - between wire/loom and switch, fuse or device can cause unwanted electrical resistance, which can be thought of as equivalent to a join or union in water pipes - and every one has the potential to restrict the flow of water/reduce the flow of electricity. When, as Dieselman says, the circuit requires clear 'on' and 'off' states, the existence of resistance at poor connections really, ahem, muddies the water (sorry).

For example, putting a multimeter on the leads that will go onto a starter solenoid might well show a healthy 12volts, but once the solenoid is connected, a good amount of current must flow through it for it to do its job. A poor connection elsewhere in the circuit is not shown up by the multimeter, as testing with one draws only the tiniest of currents. Now that a lot of current needs to flow, any poor connection will play its part and limit the current flowing through the solenoid, quite possibly to the extent that the solenoid doesn't perform. This is why tests with a device drawing the same order of current as when the circuit is in use, as suggested by Dieselman, is such a good idea.

Sorry, got my teacher's hat on there for a moment.

Carry on

I need "basic teaching" with electrics


Dug out the ignition switch from my spares v.6 Activa and after playing --Hunt the retaining screws-- with the XM's lower plastic covers I fitted the Activa one to the XM. = Same result, no starter no clicks from the ignition relay.

I only get power (1.9v) on pin No 11 I am concerned that (plug side) 12/13/14/15 are damaged however.

Those double Injection relays usually have a part number and a circuit diagram printed on the top.
There are a number of different types each with different internal pin wiring.
Check that both have the same diagram and part number or you may comparing apples with pears.

Same as in the Xantia 2.1 I have here...No 240104 (9619696580)

I had dead ignition on my v6 xm once. My fix. I left the ignition on. And on the V6 there's a bunch of relays that sit on the front of the ecu box. All I did was grab bits and shake them. I then heard the relays click and fuel system prime. A few clicks were also heard as other relays woke up. May be worth a try..