Hi All,

Have read a lot of interesting support on the site that has helped a lot on the past but never been a member.

 

My vehicle is a Skoda Fabia 1.9 TDI on a 56 plate.

My current problem:

Recently changed the cam belt, have done this before, went without too much trouble, all back together, tried to start, wouldn’t, got out the VCDS Light, did a scan, had an error on the  camshaft position sensor -G40-, ok went to the sensor probed it for voltage while still connected, all looked good, tried to start again still won’t go, went back to the sensor disconnected it and tried to start again (was pretty sure that engine should run without camshaft sensor connected ), started, with a bit of a struggle but started.

 

Ok, so it could be the camshaft sensor, could have given it a knock when I changed the belt, or it could be the wiring loom, have read a few articles on here about problems with wiring failing. I don’t have a new sensor to swap out so will check the voltages and connections to the ECU first.

 

So, with the camshaft sensor disconnected I have checked the voltages on the camshaft sensor connector:

Pin 1 (blue/black wire) +12V

Pin 2 (white/yellow wire) 5v~ to pin 109 on the 40 pin connector at the ECU

Pin 3 (brown/blue wire) -12V to pin 101 on the 40 pin connector at the ECU

 

I was expecting Pin 2 to have no voltage on it as this should be the feedback form the sensor??

 

Though this might be some sort of contamination in the wiring loom so I exposed the wiring close to the ECU and cut the wire and then tested the voltage there, it is still about 5v??

 

Don’t have a spare ECU to swap out with.

 

Any support with this will be greatly apricated.

Or the cam belt timing is far enough out to give a cam position error, it won't be the ECU.

 

Double check your cam timing.

Hi sepulchrave,

 

Thanks for the quick response.

 

I have checked the timing several times, all looks good,

While the cam sensor is disconnected the car runs fine (well sort of fine), have been driving around in it for the past few days, bit low in power but serviceable.

 

The thing that is baffling me is why would the ECU output a voltage on pin 2, surely this is an input?

 

Inputs can have so called pull-up resistors on them. The cam sensor may then pull down that line, by a transistor switching to ground, each time it sends a pulse.