Citroen SM injector points

Hi Rhys,
following the ECU-pinout to be found here at the compendium pin 12 is the ground contact for both sensors - wires connected inside the wiring harness.
Pin 14 is the connecton for the absolute pressure sensor.

Your car doesn't have a full-load-switch.

Be sure to use the correct wiring diagram.

The wiring differs from car model to car model

Regards
Norbert

Mmmm bit of a correction here –

Pin 17 is measured against pin 11 (14 will earth – but not on idle)
Pin 14 (the full load switch) should be measured against 11, but this should be 0 ohm, not infinity (as per instructions) – as the switch is normally closed, and opens on idle vacuum.

Cheers,
Rhys

Sorry Norbert,

The correction is to my notes - not yours.

My SM does certainly have a full load switch.

Wiring diagram should be correct....there are few versions available.

Cheers,
Rhys

Hi Rhys,

I have taken my information from the Bosch workshop manual. According to that Citroen DS and SM differ. On SM you should measure pin 17 against 12, on DS pin 17 against pin 14. Connection of absolute pressure switch differs also: It is pin 2 on DS and pin 14 on SM.

Regarding full-load or absolute pressure switch: that closes when engine is in full-load (no vacuum) or stalling (also no vacuum).

Hi Rhys, Hi Volker
I try to follow your explanations but still have problems in understanding.

- Rhys said the car has a full-load-switch. So says his figure from the citroen-manual ???
(or is this just a problem in using the term 'full-load-switch' instead of 'absolute pressure sensor'??
a car equipped with full-load-switch must have a TPS with 5 (connected!)connectors.

- Following the explanations of Volker, my linked measuring-plan seems to be o.k.

But an error in the Bosch service-instruction at this point would be not the first one we detect...

Please, Rhys, stay tuned with us and tell us your results.

Regards
Norbert

Hi Norbert,

well the absolute pressure switch in a way is nothing else than the full-load switch in TPS: In Citroen and early VW type 3 we had the full-load detection via this absolute pressure switch, in late cars this was done in throttle switch via a contact. Therefore absolute pressure switch is often also called full-load switch. In principle you could replace the absolute pressure switch by a proper throttle switch with full-load contact.

I have no idea why Citroen even in SM held on to absolute pressure switch and its failures in high altitudes.All other SM engineering strives for the most recent possible solution. VW type 3 is the only car that was available with all 3 kinds of full-load detection: Absolute pressure switch, full-load diaphragm and full-load contact.

And now I notice that I wrongly marked the 0 280 100 036 MAP sensor as a type 2. Of course it does not have a diaphragm. Will correct that. Therefore Rhys, I am 95% sure that is works correctly if it holds vacuum and potting has never been removed.