DESCRIPTION:Jake Brake Stage 1 Circuit Failed Low. MONITORED PARAMETER:Jake solenoid TYPICAL ENABLING CONDITIONS:Always enabled MONITOR SEQUENCE:None EXECUTION FREQUENCY:Always enabled TYPICAL DURATION:Two seconds DASH LAMPS:1. MIL2. CEL VERIFICATION:Engine idle: One minute. PROBABLE CAUSES:1. Short to ground between pin 13 of the front fuel injector valve cover harness connector and pin 66 of the 120-pin ECM connection.2. Jake brake solenoid failure.