No Spark, no signal at ecu
 

ok I have a 97 blazer 4x4

It does not get any spark, I followed a troubleshooting flow chart and it took me back to the ecu. It said look at IC circit on the vcm C3 connector. I believe this is pin 9 on the connector, I tested it and it was not getting any signal from the ecu.

Went to the yard today and got an ecu that I know works as it came off a running motor but the test still says its a bad ecu. anyone got any ideas?

I have replaced the Crank sensor, distributor cap, wires, plugs coil and ic module but still nothing. and I have followed the flow chart to check for grounds etc.

any help would be awesome

RE: No Spark, no signal at ecu
 

Attached below you will find the wiring schematic for your '97 concerning the ignition components. I would start by verifying that the white wire has continuity between the PCM and the ICM.

https://i11.photobucket.com/albums/a..._Schematic.jpg

RE: No Spark, no signal at ecu
 

awesome thanks for the schem, I will check some things this one looks different than the one I was looking at. I did do a resistance test through the wire to make sure there was no break in it between the PCM and ICM but i will be back checking grounds tonight.

RE: No Spark, no signal at ecu
 

Let me know if you need anything further.

RE: No Spark, no signal at ecu
 

well I got it running, I pulled the new CKS I put in and put the old one back in. no go. So I changed out my stock ecu for a junkyard one and vroom. started right up. Then I pulled the old CKS and put the new one back in. Started again no problem. SO I drove it to work last night it worked ok but stumbled a bit. I fifured it needed a cks variation learn. Got home parked it and was gonna go and get it done today. when I went to start it today I got nothing again.

It was snowing last night so theres alot of moisture everwhere so that may have a contributing factor but I would think it would have quit on me when I was driving if water was a problem.

Any help is awesome thanks