Hi All,
This is for the mate/mechanic next door, who helps me out a lot so I'd like to return a favour (and on top of that it's his mums car).
This car is excellently maintained as he's really picky and has done a fairly low mileage.
MIL on, read cam / crank sensor codes, no surprise on a Vauxhall then!
He informed me it was due for a cambelt so I said to do that first, which he did, quality kit with tensioner and pump. I also warned him about the fragile lug on the cam pulley.
After this we still get a P0340 cam sensor code.
Checked all wiring to ECU. There is no power from the ECU to the cam sensor which I believed to be a Hall sensor as it is the later type dropped in from the top behind the cam wheel (or will this be the rf excited type?) Never got involved this far with these before,new sensors and adjusting or replacing the cambelt has always got me out of trouble with these until now.
ECU has been to ATP for testing with no fault found
I intend to scope the cam / crank sensor next week but I am having trouble finding a set of reference waveforms.
Shaun

I think you will find that the cam sensor on these are inductive type so there you should be able to read 2 resistances.With plug disconnected and ignition on I think the voltage is around 1-1,5 volts.The hall effect sensor can be found on the 2.2 engines fitted to Omega models which run a different management system.If you have access to Bosch esi.all the info is available here.Also does it have the modified sensor and adaptor wiring harness?

I'm sure on www.picoauto.com there is a reference waveform for you to look at and it explains how it operates.

Hi Shaun

This is an AC excited type cam sensor (it is covered in the presets on Picoscope Automotive). If you scope the two outer pins at the sensor, (or better still pins 31 & 32 at the PCM) you should see an AC signal on each. It's quite a rapid signal & if the sensor is functioning correctly, you should see that the alignment of the two signals move (in relation to each other) as a ferrous object is passed close to the tip of the sensor.

A bit like this....




It's a shame you didn't deploy the scope before diving in so deep with ECU testing & the like!

You'll know for next time though hey!

Here is a link to something from the archives.

HTH

Dave

Hi All, and thanks for the replies.
Sorry about the delay but wanted to be sure it was a reliable fix.
Dave, you are right about the ECU testing but my friend who sent the unit off wanted to do something, so that is what he did. Like I said I have not had to go this far into this system before, I will not get caught again (hopefully).
I did spend a lot of time searching the archives and Pico's website with no luck for some reason.
Anyway, made basic resistance tests of old cam sensor to find coil between 2&3 open circuit, so at least I new that one was faulty. Made resistance and inductance tests of new one. Between pins 1&2- 12.7 Ohms/ 1.15 mH, 2&3- 0.7 Ohms/ less than 0.03mH. On the basis of the resistance between 2&3 I recommended a new sensor. Before fitting it I measured again, the latest one was very close to the previous new one! It was fitted anyway and guess what, out went the light and the code could be cleared.
Intending to scope the first replacement sensor I got the scope out to warm it up and after a couple of minutes the display went blank, I did not manage to repair it until after the second replacement sensor was fitted, which did give results as per the samples Dave supplied. Due to time issues it was not possible to refit the first replacement and see what was wrong with it unfortunately.
I always preach to others "just because it's new does not mean it's a good one" and fell in the trap myself. Both sensors genuine GM by the way.
Yes, I would love to have a Picoscope but unfortunately financial constraints mean no chance at the moment. The scope I use is quite old, it's an HP 400Msample/Sec DSO, but I do have 3 of them, one to use and 2 for spares!
Thanks again for advice and info, Shaun.