84k10

Hey all needing some help I can't seem to figure out with repair manuals or other information sources. Basically the issue is my cel is on constantly from start up. I've pulled the codes about a dozen times now in hopes one will finally show up but all I get is 12 on repeat. I've tried resetting the cel many times aswell with no solution. I've also gone through and checked all ground connections including the Ecm ground. Any ideas why the cel would stay on with no error codes? The truck is running great and all vaccumm readings are normal. In fact without the cel light on the trucks on point. Thanks for the help

1984 Chevy Silverado k10 5.7 California emissions.

Richard Till

Tried unhooking the battery cable for a while and reconnecting?

84k10

Yes multiple times. Have also pulled ecm fuse