GM Service Manual Online
For 1990-2009 cars only

Object Number: 97666  Size: MF
Power Door Systems Components
Door Control Module Schematics
Handling Electrostatic Discharge Sensitive Parts Notice

Circuit Description

The LH Door Control Module (LDCM) provides the LH door lock and LH heated mirror control output functions. When the LDCM detects an active door LOCK or UNLOCK command from either the LH window switch, or from a LOCK or UNLOCK message sent on the serial data line by the RH Door Control Module (RDCM), the LDCM will LOCK or UNLOCK the LH door. The LDCM accomplishes this by applying a ground or voltage to CKT 294 and CKT 295 depending on which command (LOCK or UNLOCK) was requested. The LDCM also controls the LH heated mirror functions by supplying a ground and voltage to the LH heated mirror. When the LDCM receives a message on the serial data line indicating the rear defogger was turned ON, the LDCM will activates the LH heated mirror by applying voltage to CKT 267. The LDCM monitors the voltage level and the amount of current draw on the LH door lock control circuit and the LH heated mirror control circuit. If the voltage level and/or current draw in either circuits are not within the acceptable range, a malfunction is present and a DTC will set.

Conditions for Setting the DTC

    • The LDCM detects a high current or a short to voltage condition in the LH door lock control circuit when the LH door lock is activated
    • The LDCM detects a high current or short to voltage condition in the LH heated mirror control circuit when the LH heated mirror is activated (rear window defogger is ON).
    • Condition must be present for 150 ms.
    • The LDCM detects a voltage drop of 5 volts or more at battery 2 when the LDCM activates the LH door lock or the LH heated mirror.

Action Taken When the DTC Sets

    • Stores a history DTC B2276 in the LDCM memory.
    • This DTC can only be set as a history code even if the malfunction is current.
    • No driver warning message will be displayed for this DTC.
    • Disables all LH door lock or LH heated mirror functions depending on which circuit the LDCM detected the malfunction.

Conditions for Clearing the DTC

    • The rear window defogger must be turned ON.
    • The LDCM no longer detects a high current or short to voltage condition in the LH door lock control circuit.
    • The LDCM no longer detects a high current or short to voltage condition in the LH heated mirror control circuit.
    • The LDCM no longer detects a voltage drop of 5 volts or more at battery 2 when the LDCM applies the LH door lock or LH heated mirror.
    • Use the IPC clearing DTCs feature.
    • Use a scan tool.

Diagnostic Aids

    • The following conditions may cause an intermittent malfunction:
       - There is an intermittent short to voltage in CKT 267, CKT 294 or CKT 295.
       - The LH door lock motor or LH heated mirror is shorted internally.
    • If the LDCM detects a malfunction in the LH door lock or LH heated mirror control system, the LDCM will disable the system that the malfunction was detected in.
    • Using a scan tool, select LDCM Data display and monitor battery 2  voltage while cycling the door locks. If battery 2 voltage drops more than 5 volts, then the LH door lock control circuit must be checked for a short to ground. Sense LDCM also monitors the voltage level in the LH heated mirror control circuit, this test can be applied to the heated mirror system.
    • If the DTC does not reset after the code is cleared, then the problem may be intermittent. Perform the tests shown while moving related wiring and connectors. This can often cause the malfunction to occur. Refer to Intermittents and Poor Connections .

Test Description

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

  1. This test determines if the malfunction is located in the LH heated mirror circuit or the LH door lock circuit.

  2. This test checks if the LDCM is sending the correct supply voltage to the LH heated mirror.

  3. This test checks if the LDCM is sending the correct supply voltage to the LH door lock.

DTC B2276

Step

Action

Value(s)

Yes

No

1

Were you sent here from the Power Door Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - Power Door Systems

2

Using the LH door lock switch, operate the LH lock.

Does the LH door LOCK and UNLOCK properly?

--

Go to Step 3

Go to Step 4

3

  1. Turn OFF the ignition switch.
  2. Disconnect the LH mirror connector C1.
  3. Turn ON the ignition switch.
  4. Turn ON the rear defogger.
  5. At the LH mirror connector C1 (harness side), measure the voltage between terminals B and E.

Is the voltage within the specified range?

10.0-14.0 V

Go to Step 10

Go to Step 6

4

  1. Turn OFF the ignition switch.
  2. Disconnect the LH door lock connector C3.
  3. Turn ON the ignition switch.
  4. At the LH door lock connector C3 (harness side), measure the voltage between terminals A and B.
  5. Using the LH door switch, LOCK then UNLOCK the LH door.

Is the voltage within the specified range when the LH door is LOCKED then UNLOCKED?

10.0-14.0 V

Go to Step 11

Go to Step 5

5

Check for an open or short (to ground or voltage) in CKT 295 or CKT 294.

Was a problem found and repaired?

--

Go to Step 12

Go to Step 9

6

Check for an open or short (to ground or voltage) in CKT 450 or CKT 267.

Was a problem found and repaired?

--

Go to Step 12

Go to Step 9

7

Replace the LH mirror assembly. Refer to Outside Rearview Mirror Replacement .

Is the replacement complete?

--

Go to Step 12

--

8

Replace the LH door lock assembly. Refer to Door Lock Replacement .

Is the replacement complete?

--

Go to Step 12

--

9

  1. Replace the LDCM. Refer to Door Control Module Replacement .
  2. Program the replacement DCM (hardtop only). Refer to Door Control Module Programming/RPO Configuration .

Is the replacement complete?

--

Go to Step 12

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10

Check the LH heated mirror circuit for an intermittent malfunction. Refer to Diagnostic Aids.

Was a problem found and repaired?

--

Go to Step 12

Go to Step 7

11

Check the LH door lock control circuit for an intermittent malfunction. Refer to Diagnostic Aids.

Was a problem found and repaired?

--

Go to Step 9

Go to Step 8

12

  1. Turn OFF the ignition switch.
  2. Reconnect or install any connectors or components that were disconnected or removed.
  3. Turn ON the ignition switch.
  4. Clear any DTCs.

Is the repair complete?

--

Go to Diagnostic System Check - Power Door Systems

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