P1381

Diagnostic Chart:

Schematic:

CIRCUIT DESCRIPTION
This diagnostic will detect a loss of serial communication from the Electronic Brake Control Module (EBCM) to the control module. This serial communication is essential in order to distinguish misfire from a rough road condition.

CONDITIONS FOR RUNNING THE DTC
^ The vehicle speed is 2 km/h (1 mph).
^ The engine speed is less than 5800 RPM.
^ The engine load is less than 89 percent.
^ Engine misfire is detected.

CONDITIONS FOR SETTING THE DTC
A serial data malfunction is preventing the VCM from receiving rough road detection data.

ACTION TAKEN WHEN THE DTC SETS
^ The control module stores the DTC in history after the first failure but will not illuminate the Malfunction Indicator Lamp (MIL).
^ The control module records the operating conditions at the time the diagnostic fails. The control module stores the failure information in the scan tools Freeze Frame/Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC
^ A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles.
^ A warm-up cycle occurs when the coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant temperature exceeds 70°C (160°F) during the same ignition cycle.
^ Use the scan tool Clear Information function.

DIAGNOSTIC AIDS
Check for the following conditions:

An intermittent may be caused by any of the following conditions:
^ A poor connection
^ Rubbed through wire insulation
^ A broken wire inside the insulation

Thoroughly inspect any circuitry that is suspected of causing the intermittent complaint. Refer to Testing for Intermittent and Poor Connections in Diagrams.

If a repair is necessary refer to Wiring Repairs or Connector Repairs in Diagrams.

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.
3. This step isolates an open serial data circuit from the EBCM system.