BCM DTC B334: Loss Of ECM Data: Description

DTC B334 will set if the ignition is on and the BCM is not able to exchange data with the ECM (if any other communication DTCs are stored along with B334. see SERIAL DATA CIRCUIT MULTIPLE INTERMITTENT CODES  ). When this is the only communication code stored, the problem must be one of the following:

• An open CKT 800E and 800F.
• An open or short to ground in circuit 439 or 1605.
• A faulty ECM or ECM Calpak.

During the time the failure is present, a fail soft value equal to 100°C will be used for the coolant temperature, the cooling fans will be commanded to high speed, and no ECM diagnostic information will be available for display. Also, while in the service diagnostic mode, this DTC will remain active, always checking for proper operation.