Citroen Relay X250 Starting Issue

[Adamhratcliffe]

I tested both off the car yes and both seemed find. Albeit the new one quicker when spinning.

I am not 100% it is not the battery at this stage but short of buying another one have no way of totally isolating it. Voltage drop the starter, multimeter positive on the positive connection of the starter and earth whilst cranking?

[wheeler]

No, multi meter should be connected battery positive to starter positive terminal & take a reading when trying to crank it, ideally you want 0 volts but should be no more than half a volt.
You will probably need to extend your meter lead

[Adamhratcliffe]

It’s showing 0.3 when I crank it like that with the multimeter in line to the positive post. If I touch the body of the starter it reads 12.4 so that seems like the full voltage is getting through?

[Adamhratcliffe]

I’ve done what I think is a ground voltage drop and that was 9...

[Adamhratcliffe]

Earthed my starter directly to chassis and started fine. So earthing is the issue as you said. Where is the place to start to fix this. Is it likely to be the engine earth strap?

[wheeler]

Sounds like there is corrosion on the engine to chassis earth then. Its just a case of locating it & checking where both ends bolt on for corrosion. You could also add a new heavy duty earth strap for good measure.