GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2004 🢒 Envoy - 2WD 🢒 DTC 🢒 DTC B0283

Circuit Description

The lift gate module (LGM)/end gate module (EGM) monitors the voltage level on the supply voltage circuit of the rear window defogger. The LGM/EGM test the supply voltage circuit of the rear window defogger every 160 milliseconds. With the rear window defogger inactive, the supply voltage circuit of the rear window defogger will have no voltage present. With the rear window defogger active, the supply voltage circuit of the rear window defogger will be near system voltage.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

One of the following conditions can cause this DTC to set:

    • Battery positive voltage is detected on the supply voltage circuit of the rear window defogger, while the rear window defogger is inactive.
    • Low voltage is detected on the supply voltage circuit of the rear window defogger, while the rear window defogger is active.

Action Taken When the DTC Sets

The rear window defogger is disabled.

Conditions for Clearing the DTC

A history DTC will clear after 50 consecutive ignition cycles.

The DTC will clear from current status when one of the following conditions is no longer detected:

    • Battery positive voltage on the supply voltage circuit of the rear window defogger, while the rear window defogger is inactive.
    • Low voltage on the supply voltage circuit of the rear window defogger, while the rear window defogger is active.

Step

Action

Yes

No

Schematic Reference: Defogger Schematics

Connector End View Reference: Stationary Windows Connector End Views

1

Did you perform the Defogger Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Defogger

2
  1. Turn ON the ignition, with the engine OFF.
  2. Turn OFF the rear window defogger.
  3. Connect a test lamp between the rear window defogger grid and a good ground.

Does the test lamp illuminate?

Go to Step 5

Go to Step 3

3
  1. Select the Rear Defog, from the lift gate module (LGM)/end gate module (EGM) special functions.
  2. With a scan tool, command the rear window defogger ON.

Does the test lamp illuminate?

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 4

4
  1. Turn OFF the ignition.
  2. Disconnect the harness connector C1 of the LGM/EGM.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test lamp between the battery positive voltage circuit, terminal A, of the LGM/EGM and a good ground.

Does the test lamp illuminate?

Go to Step 7

Go to Step 6

5

Test the supply voltage circuit of the rear window defogger for a short to battery positive voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 10

Go to Step 8

6

Repair the battery positive voltage circuit of the LGM/EGM for an open or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 10

--

7

Test the supply voltage circuit of the rear window defogger for a short to ground or an open. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 10

Go to Step 8

8

Inspect for poor connections at the harness connector of the LGM/EGM. 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 10

Go to Step 9

9

Important:: Perform the setup procedure for the module, if required. Refer to Control Module References in Body Control System.

Replace the module. Refer to Control Module References in Body Control System.

Did you complete the replacement?

Go to Step 10

--

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

Does the DTC reset?

Go to Step 2

System OK