What does the Camshaft Position Sensor read off of?

unseenthings

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Joined
Oct 17, 2007
Location
Peoria, IL
TDI
2004 Jetta, 2009 Q7 2010 A3
04 Jetta PD is having trouble with the Camshaft Sensor, It's not getting a reading, car runs the same with the sensor mounted in the hole or outside the hole, and doesn't run at all with sensor unplugged. We have tried new sensor and checked the wiring harness.
Thanks
Brian
 

whitedog

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Joined
Jul 12, 2004
Location
Bend, Oregon
TDI
2004 Jetta that I fill by myself
There is a toothed wheel on the camshaft gear that the sensor reads, but I get the feeling tha tthis isn't your real question and I'm not sure I would actually have the answer anyway, but what the heck, I'll throw in my pennys worth and hopefully learn something when someone smart answers.
 

unseenthings

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Oct 17, 2007
Location
Peoria, IL
TDI
2004 Jetta, 2009 Q7 2010 A3
Well, I was guessing that their would be some kind of chip or something on the camshaft and the sensor would count how many times around the camshaft is rotating and adjust the idle accordingly. And that something is missing or block or? Someone here has got to know!
 

whitedog

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Jul 12, 2004
Location
Bend, Oregon
TDI
2004 Jetta that I fill by myself
Me in my post above said:
There is a toothed wheel on the camshaft gear that the sensor reads,
Why exactly are you asking? Is there a problem that you are experiencing? If so what are the symptoms?
 

DanG144

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Aug 2, 2007
Location
Chapin, South Carolina, USA
TDI
2005 A4 Jetta 5spd
PD cam sensor normal readings

It seems odd that the car will not run with the cam sensor unplugged. My 2005 PD will; it just takes a bit longer to crank.

The cam sensor sees a wheel behind the cam sprocket. It is not a toothed wheel in the normal manner. It has pieces of metal of varying width in places, with other pieces of varying widths removed. This lets the sensor report to the ECU not just how fast the cam is turning, but also which cylinder is presently at TDC.

As I said, my 05 pd will run with the sensor unplugged. The PD educational pdf in the photo section indicates that is normal. (By the way the BEW will not run without the crank sensor, but the BRM can run as long as either the crank or the cam sensor is working.)

The cam sensors normal resistance is greater than 6 Mohms for any and all pins to ground, with either positive or negative ground.

The sensor pin to pin readings were all greater than 6 Mohms, with the following exceptions:
Pin 1 neg to pin 3 positive = 2.89 Mohm.
Pin 2 neg to pin 3 positive = 1.95 Mohm.

The plug (wiring harness) pin to ground(negative) readings (key off) are :
pin1 = 26 to 50 ohms (varying, seemed mostly 50 ohms)
Pin 2 =4.35k ohms
Pin 3 = 0 ohms.

The plug (wiring harness) pin to ground (negative) voltage readings (key on) are:
Pin 1 = 12.5 volts
Pin 2 = 5.0 volts
Pin 3 = 0 volts

When I started the car (yeah it runs) with the plug off and checked the voltages again, the only one that changed was:
Pin 1 = 14.3 volts.
 
Last edited:

TdiRacing

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Aug 19, 2003
Location
Baltimore, MD
TDI
2006 Jetta TDI Cup


You can see the wheel is attached to the harmonic balancer that the timing sprocket goes over. The fingers pass the sensor(magnetic) and it references the signal. Get a new sensor. I have replaced a few in the past and solved the issues.
 

DanG144

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Joined
Aug 2, 2007
Location
Chapin, South Carolina, USA
TDI
2005 A4 Jetta 5spd
edited post 5 above. I had copied the wrong reading down for pin 2 to pin 3.

My experience is nowhere near what TdiRacing's is - and it does not come from direct hands-on, but through long distance helping on this forum. (So treat his input as more valuable than mine.) In the few cases I have assisted with, it was always a wiring problem.

That is why I provided the readings from a known good sensor, and a known good wiring harness. You can test your sensor and harness in about 15 minutes, and know which way to go.

Checking the plug's (wiring harness) resistance with the key off, and voltage with the key on would be very telling when looking for possible wiring issues.
 

unseenthings

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Joined
Oct 17, 2007
Location
Peoria, IL
TDI
2004 Jetta, 2009 Q7 2010 A3
Well, i will try to run the car with the sensor unplugged. When the car runs (with the sensor plugged in) It runs with a bad miss, and the car with die if you don't play with the throttle. While the car is running, the rpm needle is bouncing around, not getting very high, and all the dash lights that you normally see when you turn the key over stay on.
We have replaced the cam sensor twice, because the error code we are reading from the computer is a engine speed sensor error.
Thanks for the input, I guess we pull the cam and see how that toothed wheel is looking.
 

whitedog

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Joined
Jul 12, 2004
Location
Bend, Oregon
TDI
2004 Jetta that I fill by myself
unseenthings said:
Well, i will try to run the car with the sensor unplugged. When the car runs (with the sensor plugged in) It runs with a bad miss, and the car with die if you don't play with the throttle. While the car is running, the rpm needle is bouncing around, not getting very high, and all the dash lights that you normally see when you turn the key over stay on.
We have replaced the cam sensor twice, because the error code we are reading from the computer is a engine speed sensor error.
Thanks for the input, I guess we pull the cam and see how that toothed wheel is looking.
I must have missed something. WHy have you been looking to the cam sensor if you are getting an engine speed sensor code? You should be looking at the crank sensor, I believe.
 

whitedog

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Joined
Jul 12, 2004
Location
Bend, Oregon
TDI
2004 Jetta that I fill by myself
DanG144 said:
Yea, verily. The Pale Canine speaks the truth.

What codes are being thrown? Let's back up a step here.

Look for a PM.
Heh. I know what I would name a Pale beer if I ever made one. :)
 

unseenthings

Veteran Member
Joined
Oct 17, 2007
Location
Peoria, IL
TDI
2004 Jetta, 2009 Q7 2010 A3
We stuck a camera down the sensor hole, The tines on the camshaft are bent, ***? How would this happen? We are going to pull the camshaft and take a look. Does the whole camshaft need replacing?
Thanks
 

unseenthings

Veteran Member
Joined
Oct 17, 2007
Location
Peoria, IL
TDI
2004 Jetta, 2009 Q7 2010 A3
Well, it looks the front end has been squished, so we are guessing the sensor got shoved in too deep and bent the tines. Going to try and straighten them out now, see how that goes.
 

Dimitri16V

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Joined
Jan 30, 2005
Location
DE
TDI
01 Golf, 04 Golf
i would like to know the fix for that.
i get the "implausible signal" from the cam sensor too. it seems to read fine when hooked to VCDS.
who sells those cam sensors at best price ?
 
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