Cur turns but won't start, computer hints at the cam sensor

rocky1994

Hi there,

My Opel Corsa B 2000 wont start but turns so I had a mechanic run a diagnostic test with a specialised computer computer and apparently it's the cam sensor. I checked the wires myself and multimeter reads 5v on 1st(power supply I suppose?) and 2nd pin(output signal?), the third one being the ground obviously. When I crank the engine the voltage jumps from 5v to 5.15v and remains constant for as long as I'm cranking the engine. There's also continuity between the ground pin and the negative terminal, so that seems ok. All opinions and ideas welcome and much appreciated.

Thanks in advance

dieselbug

Your meter is unlikely fast enough to be capable of measuring accurately the voltage change on the signal wire.

Better to use a tester with an led or better still, an oscilloscope will show any activity very accurately.

Pins are numbered 1 to 3

1=Ground and 3 being 5v reference.

A good scan tool will confirm if the sensor is producing a signal in sync with the crank sensor.

Tony Beetroot

What kind of specialised computer computer did your mechanic have?

martinr5232

Crank sensors gave a lot of trouble on those corsas are you sure hes not getting mixed up.

rocky1994

dieselbug wrote: »

Your meter is unlikely fast enough to be capable of measuring accurately the voltage change on the signal wire.

Better to use a tester with an led or better still, an oscilloscope will show any activity very accurately.8

Pins are numbered 1 to 3

1=Ground and 3 being 5v reference.

A good scan tool will confirm if the sensor is producing a signal in sync with the crank sensor.

To tell the truth, it is a cheapy multimeter, but it should give at least some kind of reading. Still, no explanation why signal wire gives a constant 5v when it should be 0v, or should it?

rocky1994

martinr5232 wrote: »

Crank sensors gave a lot of trouble on those corsas are you sure hes not getting mixed up.

Well, he said it's the cam sensor and he even pointed at it.

jimgoose

rocky1994 wrote: »

To tell the truth, it is a cheapy multimeter, but it should give at least some kind of reading. Still, no explanation why signal wire gives a constant 5v when it should be 0v, or should it?

That's a three-wire Hall Effect sensor. Aside from verifying that power and ground exists, you are wasting your time without a noid light and a meter with a Hz counter.

enumbers

if its the usual 1 litre 12v chain engine, will start no problem with the cam sensor disconnected, need a scan to see a fault description to go any further.

George Dalton

It has probably slipped the timing knowing those yokes...

enumbers

though it normally has to be really bad to stop them starting

PukkaStukka

Why bring a car to a mechanic, get him to scan it, and then try fix it yourself??