Code B334: Loss Of ECM Data: Notes

Code B334 will set if communication between ECM and BCM is lost. If the BCM remains powered and only serial communication is lost, the vehicle will still run, however with ignition key on (engine not running), an ELECTRICAL PROBLEM message will illuminate.

Test Number 1)  If the ECM looses power or ground, code will set since ECM cannot communicate. It is important to note that engine will not start.

Test Number 2)  Since prior checks eliminated an open circuit, fault is poor terminal contact at ECM terminal No. 2A8, a faulty CALPAK connection or a faulty ECM.