Citroen Xanita V6 Help needed Please

[co04pow]

Hi,

Was at the car today.

I started by checking continuity of as many cables as I could. Annoyingly the one I thought was broken (checked cable 120 from pin 1 to Fuse 9 on under bonnet fuse box (this does not have continuity so must be broken!)) was not broken I must have been on the wrong pin on the multi plug under the drivers side wing.

I have attached an image of the wiring diagram and coloured all the cables i have checked continuity with green pen.

I have marked where I was getting 12V with battery connected in red and one point between inside car fusebox and pin 14 on relay 1307 when ignition turned to position 2 in purple.

Also I wanted to rule out 1203 (which is the red inertia fuel cut-off switch) I was getting 12V at it so fitted a cable between pins to try and get 12V at pin 10 on relay 1304.

So Can you tell me if I an correct in saying the following:

I need 12V from ECU pin 3 through the inertia fuel cut-off switch to pin 10 on relay 1304, This will then give 12V at pin 1 and 9, supplying under bonnet Fuse 9 for the fuel pump. As well as pin 2 on relay 1307 but also 12V from pin 51 on the ECU to pin 10 on relay 1307 thus supplying pin 9 and giving 12V at under bonnet Fuse 11.

How do I know the ECU is getting power and sending it back out?

Why am I not getting 12V at pin 10 on relay 1304 even with the inertia fuel cut-off switch looped out?

Help very much appreciated.

Owen

[xantia_v6]

How are you testing continuity of the wires? Reading with a multimeter is not always accurate with a corroded wire, as it may show a low resistance, or correct voltage with no load but still not pass any current with a load applied. You need to check for voltage drop across the cable when it is carrying a load.

I think you need to take a step back and determine which voltages are present or absent at the relevant pins on the ECU and relays, I have become a bit confused.

[co04pow]

Ok,

Yes just using a multimeter for continuity.

So next time I am back I can pass 12V down each cable and see what comes out the other end and let you know values for relevant pins?

Thanks

Owen

[xantia_v6]

For the power wires, you should apply a load, such as a 20W light bulb. It also give a visible test result.

[thorter]

A good way to look for loose and dry joints in the power distribution chain is using a filament bulb, say an 18 or 21 watt. Connect one side to ground, the other to a probe and to a meter on volts, and touch this along the supply path to be checked. Obviously look for low volts as you go. Don`t probe sensors, processors and so on, but the method is fairly safe.

[thorter]

Beat me to it!

[co04pow]

Thank you for the info, I'll let you know the outcome