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replaced crankshaft position sensor now car wont start

09-10-2011, 09:48 AM
So 99 grand prix started misfiring as of lately. Eventually the ses popped up and i took it to autozone. They said that the code for the cps is what popped up. So i changed it and now the car wont start at all. It used to start just fine before that. Please help.

Tech II
09-10-2011, 10:09 AM
Crank sensors, don't cause misfires, per se......

Usually they cause a no start.....

Not sure if that code points to a crank sensor or an ICM....

Possible the sensor you put in is no good.....sure it was installed correctly(vanes of the harmonic balancer hit it?)?.....Did you bend contacts when installing the harness connector?

If the sensor is ok, it's installed correctly, and the connection is ok, it's possible that the ICM was on it's way out and finally went.....

First thing to do is check for spark and injector pulse and if rpm's are indicated....

09-10-2011, 06:43 PM
Unhook the battery for 15 minutes and then try starting it. I replaced mine and my car would not start. I took the belts and balancer back off, inspected everything, changed nothing, but the second go around I unhooked the battery. When I hooked it back up, my car started.

Also dont be discuraged if your SES light is still on when you get it running, as it may need a Cam/Crank variation learn done.

09-12-2011, 12:58 PM
Well I guess it depends on which engine you have, but isn't the "starting" crank position sensor the one on the back of the block? I've just dealt with this on another vehicle with a 3.1 and found the connector at the ICM to be faulty. The female pin connection inside the male plug would not fit snugly over the male pin in the ICM connector. Also, they are sometimes not routed correctly and touch the exhaust manifold and melt and short out. But again, don't know if this applies here.

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