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VW Passat 2.0 ALT 2003 - Fault code 16725 cam sensor implausible signal - Fixed #

Posted by Malcolm Tripp on December 16, 2008, 3:56 pm
Message modified by board administrator February 18, 2009, 3:23 pm

Just had engine recoditioned having put it all back ecu is flagging 16725 cam sensor implausible signal.

Checked wiring back to ecu pins (no pin data on Autodata for this model) !!!!!!!! found ok

Scoped sensor 5v supply 0v on earth Ov on supply, start engine and supply stays at 5v but signal goes up to 13.5v switched.

I am sure this is why its flagging a code it's seeing a voltage over load but where is it coming from there are no cross feeds and even if there were it would not be switched.

Any ideas appreciated customer is breathing down my neck !!!!!

Re: VW Passat 2003 2.0l alt engine

Posted by Dave Harney <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2603' width='330' height='300' border=0 style='border:none;'> on December 16, 2008, 4:29 pm, in reply to "VW Passat 2003 2.0l alt engine"
Dave Harney

Malcolm,
Which pins are you getting these readings from ?
1. - ?
2. - ?
3. - ?

Is the timing ok ?

Regards
Dave

You can trim a sheeps wool many times, but you can only fleece it once !

Re: VW Passat 2003 2.0l alt engine

Posted by MALCOLM TRIPP <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5337' width='330' height='300' border=0 style='border:none;'> on December 16, 2008, 4:36 pm, in reply to "Re: VW Passat 2003 2.0l alt engine"
Malcolm Tripp

pin + 5v

pin 0 batt v

pin - 0v

engine running

I did not rebuild engine but engineering firm are quite competent, if timing was out I dont see that increasing the voltage across hall sensor.

Re: VW Passat 2003 2.0l alt engine

Posted by MALCOLM TRIPP <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5337' width='330' height='300' border=0 style='border:none;'> on December 18, 2008, 4:40 pm, in reply to "Re: VW Passat 2003 2.0l alt engine"
Malcolm Tripp

Can anyone tell me what to expect on ecu pins
86 / 98 / 108

Re: VW Passat 2003 2.0l alt engine

Posted by Sean Mc Gettigan <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5291' width='330' height='300' border=0 style='border:none;'> on December 19, 2008, 8:32 am, in reply to "Re: VW Passat 2003 2.0l alt engine"
Sean McGettigan

Hi Malcolm,
"Scoped sensor 5v supply 0v on earth Ov on supply, start engine and supply stays at 5v but signal goes up to 13.5v switched."
This could be normal for this system and if its switching ok I would say it is.
As Dave says recheck the timing,its usually the chain timing at the rear thats out.
Hth Sean

Re: VW Passat 2003 2.0l alt engine

Posted by Mike Walker <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5168' width='330' height='300' border=0 style='border:none;'> on December 19, 2008, 9:04 am, in reply to "Re: VW Passat 2003 2.0l alt engine"

The supply voltage to power the Hall effect chip inside the pick-up (in this case 5v) and the output 'pull-up' voltage generated by the ECU are two different issues. There is no reason for them to be the same although on most engine management systems they are. I would suspect that there is a genuine cam timing fault or possibly , interference being picked up on the cam sensor supply.

Link: ATP Electronics the original all makes remanufactureres.

Fixed

Posted by MALCOLM TRIPP on December 20, 2008, 10:10 am, in reply to "Re: VW Passat 2003 2.0l alt engine"
Message modified by board administrator January 9, 2009, 9:08 am

Fixed #

Thank you for your input it was indeed the cam timing out.

I suppose when you put you faith in engine reconditioners you expect them to know what they are doing.

All the Hall switches I ever came across switch the supply voltage and I could not understand why we were getting 12 volts on what I took to be the signal wire, on further investigation voltage was indeed coming from the ecu and stayed live for some 30 seconds after switching off ignition.

I was not prepared to take engine apart to check, so used picoscope on cam and crank sensor (probably should have done that in the first place)and the triggers were obviously some way apart so took the car back to engineers to sort it out.

The Solus Pro definition of "implausible signal" can obviously be interpreted in various ways ie: no signal at all or there is a signal but I dont like it or the signal I see does not match another.

Anyway I can now stop tearing my hair out and wish you all a happy Christmas.

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