Crank Position Sensor

[TallPaul]

Just what is a crank position sensor? The thing looks extremely simple, but stopped me cold in the middle of I20 in Mississippi a couple weeks ago. My motorhome (a 1999) had only 11000 miles on it when this happened. How can this thing go bad?

Also, my Haynes manual says there is a camshaft position sensor. Should I change it out just in case? No, guess not as there are several other sensors also feeding into OBDII. Guess any or all of them could stop me cold. But why didn't they design it with a limp mode so I could at least have saved the 105 $ towing fee?

 

[Colt45ws]

It watches the crank to see where it is. It is at the front of the motor behind the balancer. It is a magnetic sensor and "reads" a gear behind the balancer. Usually there will be a tooth missing from the gear to indicate #1 TDC. It went bad because it was done. Who knows, maybe it was a bad part.
It could have been setup to use the camshaft position sensor to keep track of the motor in event the crank sensor failed. However I believe you would be able to keep going but not restart it once shut off.

 

[TallPaul]

It shut itself off and pegged the speedo at 105 mph. Didn't come off the peg until I drove out of the Chevy dealership.

So internally what does it consist of?

 

[Titan]

Had one on a 1990 Saab that did the same thing, with only about 2000 miles on the clock....

 

[Colt45ws]

I believe its a hall effect sensor inside. It is for sure if its a three wire sensor.

 

[TallPaul]

Yep, three wire. So are these prone to sudden death?

 

[Junior]

Sometimes sensors just go bad. Who knows. Water, heat, vibration, mechanical damage. Hard to tell. The PCM uses the information from the crank position sensor to adjust the spark and fuel timing curves.

 

[Merkava_4]

TallPaul - I got news for you, you've got a camshaft position sensor too.

 

[TallPaul]

Quote:

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TallPaul - I got news for you, you've got a camshaft position sensor too.

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Maybe I should carry the parts. Might be worth the chance slapping them on in event it dies again.

BTW, they installed a NAPA crank sensor. Hopefully NAPA is high quality.