GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2009 🢒 Vibe - AWD 🢒 Safety and Security 🢒 Supplemental Inflatable Restraints 🢒 DTC B279A

Circuit Description

If the communication line between the transponder key ECU assembly is stuck on HI output, the engine control module (ECM) will set this DTC.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B279A Theft Deterrent System Communication Line High Fixation

Conditions for Running the DTC

This DTC shall run when key is inserted into key cylinder.

Conditions for Setting the DTC

Error in communication between ECM and transponder key ECU assembly in communication line.

Action Taken When the DTC Sets

The engine will not start.

Conditions for Clearing the DTC

The DTC will clear when conditions for setting the DTC have been repaired.

Step

Action

Value(s)

Yes

No

Schematic Reference: Immobilizer Schematics

Connector End View Reference: Component Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle

2
  1. Turn OFF the ignition.
  2. Install a scan tool.
  3. Turn ON the ignition, with the engine OFF.
  4. With the scan tool, recheck to see if DTCs other than B279A are set.

Is DTC B279A the only one set?

--

Go to Step 3

Go to Diagnostic Trouble Code (DTC) List - Vehicle

3

  1. Disconnect the ECM and the transponder key ECU assembly connectors.
  2. Measure the resistance and as follows:
    3. • Transponder key ECU connector E21 terminal 13 to ECM connector A50 terminal 11
    • Transponder key ECU connector E21 terminal 13 to body ground.
  3. Measure the voltage between the transponder key ECU connector E21 and body ground.

Are the resistance and voltage measured within the specified values?

Resistance: Connector E21 terminal 13 - connector A50 terminal 11 = Below 1 Ohm

Resistance: Connector E21 terminal 13 - body ground = Below 10 Kohms or higher

Voltage: Connector E21 terminal 13 - body ground = Below 1 Volt

Go to Step 4

Go to Step 6

4
  1. Re-connect the ECM and the transponder key ECU assembly connectors.
  2. Turn ON the ignition, with the engine OFF.
  3. Measure the voltage between the ECM connector B31 terminal 104 and ECM connector A50 terminal 11.

Is the voltage measured less than or greater than the specified value?

1-11 Volts

Go to Step 8

Go to Step 5

5

Measure the voltage between the transponder key ECU connector terminal 1 and terminal 16.

Is the voltage measured within the specified value?

11-14 Volts

Go to Step 9

Go to Step 7

6

Repair or replace harness or connector between the transponder key ECU and the ECM.

Did you complete the repair or replacement?

--

Go to Step 10

--

7

Repair or replace harness or connector between the transponder key ECU terminals 1 and 16.

Did you complete the repair or replacement?

--

Go to Step 10

--

8

Replace the transponder key ECU assembly.

Did you complete the replacement?

--

Go to Step 10

--

9

Replace the ECM. Refer to Control Module References for ECM replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 10

--

10
  1. Use the scan tool in order to clear the DTC.
  2. Operate the vehicle within the Conditions for Running the DTC, as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK