Refer to Antilock Brake System Schematics in Antilock Brake Systems.
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 Engine Misfire Detected is requesting the MIL, DTC P1381 will set.
Conditions for Running the DTC
| • | Engine load is less than 87.5 percent. |
| • | Engine speed is less than 5000 RPM. |
| • | Vehicle speed is more 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 will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed. |
| • | The PCM will store conditions which were present when the DTC set as Freeze Frame/Failure Records data. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn OFF the malfunction indicator lamp (MIL) during the third consecutive trip in which the diagnostic has run and passed. |
| • | The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction. |
| • | The DTC can be cleared by using a scan tool. |
Diagnostic Aids
Inspect for the following conditions:
Many situations may lead to an intermittent condition. Perform each inspection or test as directed.
Important: : Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion.
| • | Loose terminal connection |
| - | Use a corresponding mating terminal to test for proper tension. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair. |
| - | Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair. |
| • | Damaged harness--Inspect the wiring harness for damage. If the harness inspection does not reveal a problem, observe the display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the scan tool display may indicate the location of the fault. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair. |
| • | Inspect the powertrain control module (PCM) and the engine grounds for clean and secure connections. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair. |
If the condition is determined to be intermittent, reviewing the Snapshot or Freeze Frame/Failure Records may be useful in determining when the DTC or condition was identified.
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.
-
Checks the Class II serial data circuit at the EBCM/EBTCM for correct voltage.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On Board Diagnostic (OBD) System Check? | -- | ||
Can ABS data be displayed? | -- | |||
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? | 1.0-5.0 V | |||
5 | Test for a poor connection at the EBCM. Refer to Testing for Continuity and Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Was a problem found? | -- | ||
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 Diagnostic System Check - ABS in Antilock Brake System | |
7 |
Can ABS data be displayed? | -- | System OK |
