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[al brown]

Brother in laws corsa has decided to not start, the only code showing is p0340 for cam sensor. It has 5v at the sensor plug but i have no idea how to test the sensor.
Is this likely to be the crank sensor at fault, I was having a trawl of old posts and was wondering if a failed cam sensor would stop it starting or is it more likely to be the crank sensor failed and is not showing a code and the cam sensor code is a red herring.
Any advice would be great.
Al

[Marks DTM Calib]

Failed cam sensor will result in a non start on a common rail diesel! 

To test it would require an oscilloscope.

[al brown]

Cheers mark, thought it would need a scope as the meter wouldn't see the pulse. Code reader apparently shows the engine speed as it cranks over so I guess that would mean the cs is working, although he said it also give a reading for the cam speed, or is that just a simulated reading? As is have that with the cam sensor unplugged also.
Many thanks Al

[al brown]

We  are gonna try a cam sensor, my scanner picks up engine speed on the starter which I assume comes from crank sensor, at the same time I had the cam sensor unplugged and connected to a scope. The scope picked up about 25rpm as soon as I turned the starter but that then dropped almost straight away to zero whilst the engine speed reading on code reader stayed at about 200 rpm.
Would a genuine sensor be the only way or does it not matter on these little diesel engines?

Cheers

[al brown]

Well, cam sensor didn't help. It is now showing about 100rpm on the scope via the cam sensor. Does anyone know where the engine speed signal comes from as the engine is showing about 200rpm on the started so would that mean the crank sensor is OK or does the speed signal come from somewhere else? It has fuel pressure in the rail so I am sort of at a loss as to why it won't start. Internet has suggested these engines suffer from cam timing issues.
Any ideas would be great

[Rods2]

I would expect the crank sensor to show double the rpm as remember a 4 stroke goes through 2 crank cycles for each valve cycle.

[al brown]

Cheers, I am happy with the relative speed of the cam and crank. I am just trying to work out where the engine speed signal comes from, as I get cam speed even with the sensor unplugged. I will try the wiring diagrams tomorrow to see where the signal comes from, ie is it from the crank sensor or else where.
Still getting the p0340 signal low code even with the new sensor, so an thinking it is the cam/crank sensors disagreeing, either because the cs is goose or the cam timing is out.
Can't think why else it wouldn't even attempt to start, code reader shows it is generating the desired fuel pressure in the rail.
Cheers for any help

[TheBoy]

I know nothing about 1.3 Corsa's, but was the sensor a good branded one. The p0340 still points to cam sensor. Could, of course, be the wiring...

[al brown]

I know nothing about 1.3 Corsa's, but was the sensor a good branded one. The p0340 still points to cam sensor. Could, of course, be the wiring...

Delphi, old sensor showed approx 1250 rpm as soon as you turned the key which dropped to zero almost straight away new one shows around 100 constantly while cranking. Today's job is to find the wiring diagram so I can check the wire to the ecu. Of course he could be unlucky and it grew 2 faults overnight.
Was hoping someone one where the rpm signal comes from, it shows 200 rpm on the starter so does that show the cs is OK. Will jack it up today and see if I can get the scope on the cs.
Cheers

[Marks DTM Calib]

Crank sensor is always the source of engine rpm.

[al brown]

Cheers Mark,
That would suggest the cs is OK then, wiring checks here we go.

[andrew-v8]

might be off topic but brother had an 03 diesel corsa which turn over but failed to start, ended up being the key at fault.

[al brown]

Cheers, had thought about that, but as it's showing the cam code and it seems to register the key with the immobiliser I ruled that out. It is showing fuel pressure in the rail when I crank it but as mark said, it needs the cam sensor working to start a diesel.
Today checked the wiring out and it all seems fine, continuity through to the ecu from the can sensor, am starting to think the timing is out as a Google search has suggested it is common on these engines.
Thanks for advice though, any help is appreciated

[serek]

Cheers, had thought about that, but as it's showing the cam code and it seems to register the key with the immobiliser I ruled that out. It is showing fuel pressure in the rail when I crank it but as mark said, it needs the cam sensor working to start a diesel.
Today checked the wiring out and it all seems fine, continuity through to the ecu from the can sensor, am starting to think the timing is out as a Google search has suggested it is common on these engines.
Thanks for advice though, any help is appreciated

so car crank but not start?
if so did you ever replace egr valve?
try to un plug maf sensor and see if start
thanks

[al brown]

Cheers, had thought about that, but as it's showing the cam code and it seems to register the key with the immobiliser I ruled that out. It is showing fuel pressure in the rail when I crank it but as mark said, it needs the cam sensor working to start a diesel.
Today checked the wiring out and it all seems fine, continuity through to the ecu from the can sensor, am starting to think the timing is out as a Google search has suggested it is common on these engines.
Thanks for advice though, any help is appreciated

so car crank but not start?
if so did you ever replace egr valve?
try to un plug maf sensor and see if start
thanks

Yes, it cranks but won't start, ecu keeps logging p0340 cam sensor low input.
Haven't tried removing the egr, didn't know that could stop it starting. Have had the maf unplugged and it still doesn't start. The fuel pressure builds up quickly to the desired pressure and I have check most of the other sensors I can think of, but as Mark suggested, if it is getting a cam code a common rail diesel won't start.
Trouble is trying to work out why it's getting the code.
I have checked the cam sensor with a scope both direct on the sensor and at the ecu and there is a signal when I crank the engine but it still logs a code, so I am left with either the ecu or timing being out.
Just need to fix the seal on my jack so I can get the timing cover off.

Cheers for all the ideas