P0318

DTC P0318

CIRCUIT DESCRIPTION
Rough roads cause torque on the tires that is transmitted to the powertrain. This slows down the crankshaft giving the appearance of a misfire. The electronic brake control module (EBCM) determines rough road surfaces using input from the wheel speed sensors. The EBCM then sends the rough road data to the engine control module (ECM) via class 2 serial data. The data allows the ECM to distinguish the crankshaft speed variations caused by rough road surfaces from those caused by true misfires. If a loss of communication occurs that causes the PCM not to receive rough road information while a misfire condition is requesting the malfunction indicator lamp (MIL), DTC P0318 will set.

CONDITIONS FOR RUNNING THE DTC
DTC P0300 is occurring and requesting the MIL to be illuminated.

CONDITIONS FOR SETTING THE DTC
The PCM is detecting a loss of communication with the EBCM for approximately 12 seconds or more.

ACTION TAKEN WHEN THE DTC SETS
- The control module stores the DTC information into memory when the diagnostic runs and fails.
- The malfunction indicator lamp (MIL) will not illuminate.
- The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
- The driver information center, if equipped, may display a message.

CONDITIONS FOR CLEARING THE DTC
- A current DTC Last Test Failed clears when the diagnostic runs and passes.
- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
- Clear the DTC with a scan tool.

TEST DESCRIPTION

Steps 1-2:

The number below refers to the step number on the diagnostic table.
2. This step ensures that the EBCM is capable of transmitting serial data on the class 2 serial data circuit.