my ALDL will not communicate with my ECM. The ECM is new. was wondering if there is a fuse or something simple that others have found to cause this problem before i start searching for bad wires in the dash. Thanks.

 

There isn't a fuse in the ALDL line if that is what you are thinking. At key-on/engine-off the SES should turn on, blink off, then turn on solid. As long at it does that the ECM has power and is running from the PROM.

Note that a 10K resistor is required between A&B on the ALDL connector to scan your ECM. Although the resistor can and should be removed once communication has been established.

RBob.

 

I read about that 10K resistor and it said some cars need it and some don't but didn't clarify which did or didn't. I will try that Thanks for the help.

 

Well i tried the 10K resistor and it didn't fix anything. I also checked my ALDL ports that connect to the ECM and they were bouncing from 3.5-4.3 volts and kept bouncing back and forth. That doesn't seem right but i'm not sure what would cause that. Also i checked the voltage at the ECM A6 and A9 pins. One was at 5.0 constant, other a constant 11.50. I don't get it whats goin on?