GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 1999 🢒 Riviera 🢒 DTC 🢒 DTC P1381 Misfire Detected - No Communication with Brake Control Module

Refer to Engine Controls Schematics

Cell 20: TCC Switch, Transaxle Solenoids


Object Number: 381069 Size: FS
Engine Controls Components
Powertrain Control Module Description
Cell 20: Transaxle - Sensors and TR Switch
Cell 20: Generator, Oil Level Switch, EBTCM
OBD II Symbol Description Notice
Cell 10: HVAC RELAY Fuse and CLNG FAN Fuse (Buick)
Cell 10: Battery
Cell 10: HVAC RELAY Fuse and CLNG FAN Fuse (Buick)
Cell 10: OXYGEN SENSORS Fuse (Buick)
Cell 34: Multifunction Lever
Handling ESD Sensitive Parts Notice
Powertrain Control Module Connector End Views
 for a wiring diagram.

Circuit Description

The PCM receives rough road information from the EBCM / EBTCM on the serial UART 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 imputs 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%.
    • Engine speed is less than 5000 RPM.
    • Vehicle speed is greater 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 10 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 backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and 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.

Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.

Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table.

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

    2.

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

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

Step

Action

Value(s)

Yes

No

1

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

  1. Turn ON the ignition.
  2. Select chassis application on the scan tool.
  3. Attempt to display ABS data on the scan tool.

Can ABS data be displayed?

--

Go to Step 3

Go to Step 4

3
  1. Check 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 Intermittents and Poor Connections Diagnosis and Repairing Connector Terminals .

Was a problem found?

--

System OK

Go to Diagnostic Aids

4

  1. Turn OFF the ignition.
  2. Disconnect the EBCM.
  3. Turn ON the ignition.
  4. Measure voltage on the serial data circuit at the EBCM harness connector, using a Digital Multimeter.

Does voltage vary within a range between the specified values?

1-5V

Go to Step 5

Go to Step 6

5
  1. Check for a poor connection at the EBCM/EBTCM.
  2. If a problem is found, replace terminal(s) as necessary. Refer to Intermittents and Poor Connections Diagnosis and Repairing Connector Terminals .

Was a problem found?

--

Go to Step 7

Go to Step 6

6
  1. Check for an open in the serial data circuit to the EBCM/EBTCM. Refer to UART Data Line in Data Link Connector Schematics.
  2. If a problem is found, repair as necessary. Refer to Wiring Repairs .

Was a problem found?

--

Go to Step 7

Go to Diagnostic System Check - ABS

7
  1. Turn ON the ignition.
  2. Select chassis application on the scan tool.
  3. Attempt to display ABS data on the scan tool.

Can ABS data be displayed?

--

System OK

Go to Step 4