Code B334, Loss Of ECM Data: Notes

Fig 1: Code B334, Wiring Diagram Loss Of ECM Data

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, with ignition key on (engine not running), a "Low Oil Pressure" message will be displayed followed by an "Electrical Problem" message about 25 seconds later.

1. If the ECM loses power or ground, code will set since ECM cannot communicate. It is important to note that engine will not start.
2. Since prior checks eliminated an open circuit, fault is poor terminal contact at ECM terminal "A8", a faulty CALPAK connection or a faulty ECM.