Hello, I have a 99 blazer that will crank but am not getting any spark. I found a trouble shooting guide for the ICM module online The ICM has power to it and a good ground but when cranking the engine I have no light on my tester. On either of the other two wires. I replaced to crank shaft position sensor with no luck. Any help would be greatly appreciated.

 

Note that the test should have been done with a test light hooked to power (12V).


I prefer to look at things another way.


So do you have 12V power to the coil itself on the pink wire with the key on? If so, disconnect the ICM connector and with the key on probe the harness terminal for the white/black wire. It should light a test light hooked to battery ground. If so, jumper the white/black wire to ground and then immediately break the connection (ICM still unplugged). The coil should fire when the connection is broken. This can be easily observed by plugging a spark plug onto the end of the coil wire that goes to the distributor cap and grouding it.

Report please.

p.s. now that you have disturbed the crank sensor (probably needlessly), once this vehicle is running again you will need to do a crank sensor relearn (or have it done). Otherwise the misfire detection will be screwed up and the SES light will be on. This takes a pretty high-end scanner.


Or you can do it per the factory manual if you like. See diagnostic charts below.

 

Thank you for your input and chart. It will be a few days before I have some time off to work on it. Will let you know how it turns out. Thanks again

 

We always have time for those who will help themselves. Let us know.

Best wishes for a successful repair!