GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2003 🢒 Corvette 🢒 Body and Accessories 🢒 Doors 🢒 DTC B2276-B2277

Circuit Description

The driver door module (DDM) and passenger door module (PDM) provide the door lock motor control output functions. These output controls allow the DDM and PDM to command the door lock motors to Lock and Unlock. When the DDM or PDM detects an active lock or unlock input from a door lock switch, the DDM or PDM will command the door lock motor to Lock or Unlock . Each door module accomplishes this by applying voltage to the door lock or unlock control circuit depending on the desired action. Each door module monitors the control circuits voltage. If the voltage level drops below 7 volts for longer than 200 milliseconds, a DTC is set.

The DDM and PDM also provide the mirror heater control output functions. These output controls allow the DDM and PDM to command the mirror heaters to switch on. When the DDM and PDM receive a message on the serial data line indicating the rear defogger was turned ON, they will activate their respective mirror heater by applying voltage to the mirror heater control circuit. Each door module monitors the control circuits voltage. If the voltage level drops below 7 volts for longer than 200 milliseconds, a DTC is set.

Conditions for Setting the DTC
    • The DDM and PDM detects a voltage level drop below 7 volts in a door lock control circuit when a door lock is activated.
    • The DDM and PDM detects a voltage level drop below 7 volts in a mirror heater control circuit when a mirror heater is activated.
    • Condition must be present for longer than 200 milliseconds.

Action Taken When the DTC Sets
    • Stores a history DTC B2276 or B2277 in DDM or PDM memory.
    • These DTCs can only be set as a history code even if the malfunction is current.
    • No driver warning message will be displayed for this DTC.

Conditions for Clearing the DTC
    • The DDM or PDM no longer detects a voltage level drop below 7 volts in a door lock control circuit when a door lock is activated or a voltage level drop below 7 volts in a mirror heater control circuit when a mirror heater is activated, and:
    • The DTC is cleared using the IPC clearing feature, or
    • The DTC is cleared using a scan tool.

Diagnostic Aids
    • The following conditions may cause an intermittent malfunction:
       - There is an intermittent short to ground in a door lock control circuit.
       - There is an intermittent short to ground in a mirror heater control circuit.
       - A door lock motor or mirror heater is shorted internally.
    • If the DTC does not reset after the code is cleared, then the problem may be intermittent. 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. Tests the mirror heater control circuit for a short to ground.

    2.

  2. Tests the door lock actuator lock control circuit for a short to ground.

    3.

  3. Tests the door lock actuator unlock control circuit for a short to ground.

Step

Action

Yes

No

Schematic Reference: Door Control Module Schematics

Connector End View Reference: Power Door Systems Connector End Views

1

Did you perform the Power Door Systems Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Door Systems

2

  1. Install a scan tool.
  2. Turn the ignition on, with the engine off.
  3. With a scan tool, observe the mirror heater parameter in the appropriate Door Control Module data list.

Does the scan tool display Active?

Go to Step 5

Go to Step 3

3

With a scan tool, observe the door lock motor parameter in the appropriate Door Control Module data list.

Does the scan tool display Active?

Go to Step 6

Go to Step 4

4

With a scan tool, observe the door unlock motor parameter in the appropriate Door Control Module data list.

Does the scan tool display Active?

Go to Step 7

Go to Step 8

5

Test the appropriate mirror heater control circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 12

Go to Step 8

6

Test the appropriate door lock actuator lock control circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 12

Go to Step 9

7

Test the appropriate door lock actuator unlock control circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 12

Go to Step 9

8

Inspect for poor connections at the harness connector of the appropriate door module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 12

Go to Step 10

9

Inspect for poor connections at the harness connector of the appropriate door lock motor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 12

Go to Step 11

10

Replace the appropriate door module. Refer to Door Control Module Replacement .

Did you complete the replacement?

Go to Step 12

--

11

Replace the appropriate door lock motor. Refer to Door Lock Replacement .

Did you complete the replacement?

Go to Step 12

--

12
  1. Use the scan tool in order to clear the DTCs.
  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