Any way to test the crank sensor that's still on the motor in the car?

[NORMAN]

Hi all,

Would there be a simple way to test a suspect crank position sensor that is still on the motor in my friend's '89 SHO? That way we would be sure of it's condition before tearing into the motor for the 2nd time in a couple of weeks..

We did an engine swap, and now it wouldn't start. We are not getting any tachometer activity while cranking the motor.. I suspect a shot CKP..

Please help..

Thanks, Norm

 

[projectSHO89]

Yeah, I posted this on the mailing list awhile back and again a little while ago. Hope it helps.

A few random tips...

Hook up a timing light to the #5 plugwire and see if there is or isn't spark
when cranked.

Verify that Vbatt is at the RED/LIGHT GREEN Wire at the coil pack with IGN
in RUN. You should also measure Vbatt at the other three coil terminals as
long as the coil is not open.

Unplug the cam sensor. The car will run without it but may take several
attempts to start (under normal conditions). If it's shorted, it would ****
the CID signal by shorting it to ground.

You can measure the output of the cam and crank sensors with a meter as the
engine is rotated with IGN in RUN. The output of the cam sensor will be a 0
to Vbatt squarewave with one period per cam revolution. The output of the
cam sensor can be picked up at the DIS, connector C2, LT BLUE wire. The
output of the crank sensor will be a squarewave of 0 to Vbatt with three
periods per crank revolution. The output of the crank sensor can be picked
up at the DIS, connector C2, GRAY wire. Be sure both front wheels are off
the ground while doing these tests.

End rambling.

Steve

 

[rangerj]

Steve,

This is an absolutely fantastic response. Thank you.

SHOTHANG,

I hope you read Steve's response. This is the kind of diagnostic testing I was talking about in response to your "Codes" question. This is the difference between a "parts changer", and a real mechanic.

Steve, again, this is superb. rangerj