Oil light comes on when clutch is depressed
 

Hi all,
This is my first post on here so please be gentle........
I bought a 55 plate 2.0 diesel back in September last year. She drives very very well and gives good MPG.
Recently though when i depress the clutch the engine dies, the oil light comes on and then very soon after the battery light comes on.
I assume the battery light is because the engine has died.
The car will start instantly again if i turn off and on again or if i am traveling fast enough then is bump start itself.
I have changed the fuel filter and added a good quality diesel system cleaner but still doing the same.
I have no problems starting the car in any weather and when she is driving she pulls very well.
The only thing i can think of is the oil pressure switch??
I am a reasonably competent driveway mechanic............so as long as not to complicated i would have a go.

Any ideas would be greatly appreciated.

As the brake fluid reservoir also supplies the clutch fluid also, I wonder if the slight drop in reservoir level when depressing the clutch pedal is triggering the low brake fluid level switch ?


Paul.

Didnt know it served both, but why would that cause the engine to die and the oil light to come on?

Although I'm not familiar with the clutch system in your car, if it is twined with the braking system then is the vacuum servo also twinned? if so, the fault may be with the servo leaking and allowing unmetered air into the engine giving an over lean mix. Just a thought?

The clutch pedal has a switch, this tells the cruise control to disengage, also the fluid level switch previously mentioned.
If the wiring had a fault, possibly bad ground on one of the several ecm wires, or a short somewhere else ?

Paul.

OK, ................Checked the clutch/brake fluid level and all is fine.
I have since changed the oil pressure switch, camshaft and crankshaft sensor and it is still doing the same.
Someone has mentioned previously about "knock" sensors.................is this worth considering?
It seems to cut out more often when the revs have been above 3000rpm.
If i slow down using the gears and let the revs die slowly its fine, but if i brake hard and have to press the clutch without changing gear then it usually stalls.

Any ideas please again??

OK, so how does one stop a diesel engine ? On a petrol engine one turns off the ignition. On a modern engine, this is shutdown on the ECU, so no spark - engine stops, but a diesel has no ignition system.

Well, on a diesel you have to turn off the fuel supply. With modern common rail diesel engines like yours, the fuel is injected using electric fuel injectors operated by a similar Engine Control Unit. There is also a high-pressure pump to charge up the fuel rail to a very high pressure. The ECU has to fire the fuel injectors at a very precise moment, so gets this information in the same way as a modern petrol engine, namely from a Crankshaft Position Sensor, and also a Camshaft Position Sensor. From these two the system can fire the right injector.

So when you are pushing the clutch in, this is somehow affecting the electronic circuits somewhere. The only thing I can think of is the mechanical action of the clutch is shorting out a circuit, or there is a switch on the clutch mechanism that has an input to the ECU, and this switch is defective.

Anyway, that is my tuppenyworth !!