Citroen SM doesnt start

Hi Johan,
you have to test this using an Ohmmeter, not a Voltmeter.
Did you do it this way?
Resistance has to be almost 'zero' for two seconds when switching ignition on - (continuous during start), then return to infinite Ohms.

Regards
Norbert

Aha, I thought I would have a 12V signal through the ECU but obviously the ECU should ground the relay through pin19?
I have no breakout cable so I have to use the needle again to start measure again.

No I got almost The Same value with my crude equipment, in the mega ohm range.
Some difference but it didnt fall to zero.

Still The same conclusion about faulty ECU?
Repairing ECU sounds like a lengthy and expensive business. Is Bosch only source?

Regards
Johan

Hi Norbert,

sorry to contradict Norbert. Easieast way is to measure pin 19 against +12V. That would show nothing when fuel pump is off and -12V when ECU switches ON fuel pump.

Volker you mean zero V or +12V?
I got roughly 12V

Tjena Johan,

ECU puts this output actively on 0V to activate fuel pump relay. That is why I say measure against +12V.