GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2002 🢒 Impala 🢒 DTC 🢒 DTC P1381

Circuit Description

The powertrain control module (PCM) receives rough road information from the electronic brake control module (EBCM) on the serial data circuit. 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 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 malfunction indicator lamp (MIL), DTC P1381 will set.

Conditions for Running the DTC
    • The engine load is less than 87 percent.
    • The engine speed is less than 5,000 RPM.
    • The vehicle speed is greater than 16 km/h (10 mph).
    • A misfire diagnostic trouble code (DTC) is occurring and is requesting the MIL to be illuminated.

Conditions for Setting the DTC

The PCM is detecting a loss of communication with the EBCM for at least 5 seconds.

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.

Diagnostic Aids

If the condition is intermittent, refer to Intermittent Conditions .

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step ensures that the EBCM is capable of transmitting the serial data on the serial data circuit.

    2.

  2. Test the serial data circuit at the EBCM for correct voltage.

Step

Action

Values

Yes

No

Schematic Reference: Data Link Connector Schematics in Data Link Communications

1

Did you perform the Diagnostic System Check-Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

  1. Turn ON the ignition, with the engine OFF.
  2. Attempt to display ABS data on the scan tool.

Can ABS data be displayed?

--

Go to Step 3

Go to Step 4

3
  1. Test and inspect the serial data circuit for an open or a poor connection between the PCM and the EBCM.
  2. If a condition is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 7

Go to Step 4

4

  1. Turn OFF the ignition.
  2. Disconnect the EBCM.
  3. Turn ON the ignition, with the engine OFF.
  4. Using a DMM, measure voltage on the serial data circuit at the EBCM harness connector.

Does voltage vary within the specified values?

1-5 V

Go to Step 5

Go to Step 6

5
  1. Inspect for a poor connection at the EBCM.
  2. If a condition is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 7

Go to Step 6

6
  1. Check for an open in the serial data circuit to the EBCM.
  2. If a condition is found, repair as necessary. 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 System

7
  1. Turn ON the ignition, with the engine OFF.
  2. Attempt to display ABS data on the scan tool.

Can ABS data be displayed?

--

Go to Step 8

Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications

8
  1. Use the scan tool in order to clear the DTCs.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC run and pass?

--

Go to Step 9

Go to Step 2

9

With a scan tool, observe the stored information, Capture Info.

Does the scan tool display any DTCs that you have not diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK