My 2001 express 5.7 has low idle issue.
It had a misfire code:
-changed plugs
-changed distributor cap and rotor
-ohmed out plug wiring
-alternator replaced as well as battery
-found engine to frame ground strap severely corroded and replaced it.
-changed idle control valve
-cleaned mass air flow sensor
-found air line leaking to PVC valve
-engine codes cleared and new light came on stating PCM is not communicating with brake control valve. P1381 code.

Where is PCM located and is it a DIY task?

-Curt

 

 

Another post if found googling that code.....


The P0300 is misfire detected. The P1381 is a loss of communication between the PCM and the electronic brake control module. You are going to have to have a scan tool for this note just a code reader. This is a complex diagnosis and I can't possibly convey all of the steps here. It is possible that you have a poor connection at the plug for either one of the ecm's. It's a long shot but you can try unplugging and re-plugging the harness going to both of them. Also check the ecm grounds, there is one at the back of the left cylinder head and a one at on a stud at the thermostat housing. Otherwise, this is not really a diy type of repair.