My sentry light stays on after failed attempts to start engine. Replaced Crankshaft Position Sensor even though I am getting zero voltage to it from the ECM. I get gas but no spark, fuses good and autoscanner can not communicate to ECM. If ECM is bad how can I verify?

 

Usually only have to lock and unlock the door with the key... The module that controls that is usually seperate from the computer and is mainly intended as an anti-theft unit

 

You have to check the module

This should help
www.scribd.com/.../Jeep-XJ-2000-08qa-Vehicle-Theft-Security-Systems

 

Links not working.

 

Sorry
Just put it your search engine and it will come up

Chances are he is going to have to take it to the dealer so they can scan it with their overpriced drb, but it will show you a way of testing it your self with a volt meter. I would just be carefull not to f anything up.

 

Check and see if the PCM is showing any fault codes.>->Retrieving codes: http://www.wjjeeps.com/faultcodes.htm

 

what year is the cherokee

 

2000 jeep grand cherokee, no fault codes even though the engine light comes on after a few attempts to start. Scanner also cannot communicate with ECM.

 

Sounds like it is in anti-theft mode.

The computer is not recognizing the key.

Dealer time.

 

if you have a second key try that one if not you might need to get a new key they can come uncoded over the years

 

to reset after a failed start with the anti theft system
you need to use a valid key in the ignition turn to on then off do not try to start

if that doesn't work try to lock and unlock the door or tailgate