Circuit Description
The PCM uses the rough road information to enhance the misfire diagnostic by distinguishing crankshaft speed variations caused by driving on rough road surfaces from variations caused by true misfires. The EBCM/EBTCM transmits rough road information based on inputs from the wheel speed sensors. If a loss of communication occurs which causes the PCM not to receive rough road information while DTC P0300 is requesting the MIL, DTC P1381 will set.
Conditions for Running the DTC
| • | Engine load is less than 87 percent. |
| • | Engine speed is less than 5000 RPM. |
| • | Vehicle speed is greater than 16 km/h (10 mph). |
| • | A misfire DTC 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 / EBTCM for at least 5 seconds.
Action Taken When the DTC Sets
The PCM stores conditions which were present when the DTC set as Failure Records only. This information will not be stored as Freeze Frame Records.
Conditions for Clearing the MIL/DTC
| • | The DTC becomes history when the conditions for setting the DTC are no longer present. |
| • | The history DTC clears after 40 malfunction free warm-up cycles. |
| • | The PCM receives a clear code command from the scan tool. |
Test Description
The numbers below refer to the step numbers on the diagnostic table:
-
Ensures that the EBCM/EBTCM is capable of transmitting serial data on the Class II serial data circuit.
-
Tests the Class II serial data circuit at the EBCM/EBTCM for correct voltage.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |
Can ABS data be displayed? | -- | Go to Step 3 | Go to Step 4 | |
3 | Test the serial data circuit for an open or a poor connection between the PCM and the EBCM. Refer to Testing for Continuity , and Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Did you find and correct the condition? | -- | System OK | Go to Diagnostic Aids |
Does voltage vary within a range between the specified values? | 1-5 V | Go to Step 5 | Go to Step 6 | |
5 | Inspect for a poor connection at the EBCM. Refer to Testing for Continuity , and Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 7 | Go to Step 6 |
6 | Test for an open in the serial data circuit to the EBCM. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 7 | Go to Diagnostic System Check - ABS in Antilock Brake Systems |
7 |
Can ABS data be displayed? | -- | System OK | Go to Step 4 |
