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For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2000 🢒 Impala 🢒 Engine 🢒 Engine Controls - 3.8L 🢒 DTC P1381 Misfire Detected - No Communication with Brake Control Module

Refer to Data Link Communications Data Link Connector Schematics .

Circuit Description

The PCM receives rough road information from the EBCM / EBTCM on the Class 2 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 / 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 setting, DTC P1381 will set.

Conditions for Running the DTC
    • The engine load is less than 87 percent.
    • The engine speed is less than 5000 RPM.
    • The vehicle speed is more than 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.

Diagnostic Aids

Check for the following conditions:

    • Poor connection at the PCM or at the EBCM / EBTCM -- Inspect harness connectors for the following conditions:
       - Backed out terminals
       -  Improper mating
       - Broken locks
       - Improperly formed or damaged terminals
       -  Poor terminal to wire connection
    • Damaged harness -- Inspect the wiring harness for damage. If the harness appears to be OK, observe ABS data on the scan tool while moving connectors and wiring harnesses related to the EBCM / EBTCM. A loss of ABS data will indicate the location of the malfunction.

If the DTC cannot be duplicated and is determined to be intermittent, reviewing the Failure Records can be useful in determining when the DTC was last set. Also refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Test Description

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

  1. Ensures that the EBCM/EBTCM is capable of transmitting serial data on the Class 2 serial data circuit.

    2.

  2. Checks the Class II serial data circuit at the EBCM/EBTCM for correct voltage.

DTC P1381 - Misfire Detected - No EBCM/PCM Serial Data

Step

Action

Values

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

Important: If U1040 is also set, perform DTC U1XXX Lost Communication with XXX first.

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

Can ABS data be displayed?

--

System OK

Go to Step 4

3
  1. Test the serial data circuit for an open or a poor connection between the PCM and the EBCM.
  2. If a problem 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 Systems.

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 Class II serial data circuit at the EBCM harness connector.

Is voltage present and varying?

--

Go to Step 5

Go to Step 6

5
  1. Inspect for a poor connection at the EBCM.
  2. If a problem 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. Test for an open in the serial data circuit to the EBCM. Refer to Data Link Connector Schematics in Data Link Communications for a complete mechanization.
  2. If a problem 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 Systems.

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?

--

System OK

Go to Step 4