Camshaft and Crankshaft positioning sensor

[sisdavid]

How do I test my camshaft and crankshaft positioning sensors. can I use a multi tester. Also, What should the reading be and I have been told that you do not get a check engine light if these go bad is this true?

[dougbfresh]

You do get a check engine on the crankshaft sensor going bad and there are code for the cam sensor. On GM's you get no spark conditions on a bad crank sensor and no Injector firing with a bad cam sensor. These are GENERAL rules of thumb. What's going on with the car?

[sisdavid]

OOOOps I almost forgot where are the Camshaft and Crankshaft positioning sensors located?

[dougbfresh]

Not knowing WHAT car we're talking about it hard to say, but generally there are on the front of the motor. The Crank sensor is somewhere near the front of the crankshaft, usually behind the harmonic balancer. The cam sensor is usually somewhere near the from close to the timing gear but there are several different designs I've seen. Need to know what vehicle.

By the way, you should not start another thread for the same question, just go to the 1st one you started.

[carsandcycles]

I merged the two same topic threads.

[thecarguy]

You cannot use a regular meeter. You will need a digital oscilliscope and a set of back probes, depending on where the sensor is and whats around it you will want some long flexable back probes.

Your graphs will look somthing like this....

Your graph will have a greater frequency (mountians and valleys closer together) with higher RPM and less frequency will less RPM. Most import crank/cam sensors use 5 volts max.

A cam/crank sensor starting to go out will cause a bit of hesitation or a little stumble on acceleration. A bad sensor will keep the vehicle from running at all.

If this is a nissan or infiniti there are crank/cam recalls.

[dougbfresh]

But if the ECM loses contact with either sensor on many OBD systems, it will set a code. I doubt he has a way to scope this, but there are symptoms and ECM codes that can help track it down. Last one I had go on my Pontiac set a "Crank sensor" code and I got intermittant fire at the plugs even though the injectors were firing. Turned out to be a flake of rust between the sensor pickup and the crank wheel. Still had to pull the balancer to find it. The scope is the definative diagnostic though, but you can still Shadetree it out at times if you can read the codes and get some other info like spark and fuel readings.

[thecarguy]

I never said it wouldnt......