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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1393 (Door System, Mirror System & Window System) >> Diagnostic Information and Procedures >> DTC B1721 >> Conditions for Clearing the MIL/DTC

Conditions for Clearing the MIL/DTC

WARNING: This page is about a different car, the 2002 Oldsmobile Bravada, 2002 GMC Envoy XL, 2002 GMC Envoy, and 2002 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.

When the fault is no longer present, the door module changes the current DTC to a history DTC. The door module will clear the history DTC after 50 fault free ignition cycles, or in response to a scan tool command.

DTC B1721

Step Action Value(s) Yes No
1 Did you perform the Door Systems Diagnostic System Check? - Go to Step 2  Go to Diagnostic System Check - Door Systems 
2
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. Place the mirror direction switch in the IDLE position.
  4. With a scan tool, observe the Mirror Switch Horizontal data parameter in the door module data list.
Does the scan tool display Idle?		 - Go to Step 3  Go to Step 4 
3
  1. Activate the mirror direction switch to both the left and right positions.
  2. With the scan tool, observe the Mirror Switch Horizontal data parameter.
Does the Mirror Switch Horizontal data parameter change state appropriately with each selection?		 - Go toTesting for Intermittent Conditions and Poor Connections in Wiring Systems Go to Step 4 
4
  1. Disconnect the mirror switch.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, observe the Mirror Switch Horizontal data parameter.
Does the scan tool display Idle?		 - Go to Step 7  Go to Step 5 
5 Inspect for poor connections at the harness connector of the driver door module. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 8  Go to Step 6 
6
IMPORTANT: Perform the set up procedure for the driver door module. Refer to DCM Programming/RPO Configuration .
Replace the driver door module. Refer to Switch Replacement - Door Lock and Side Window - Driver .Did you complete the replacement?		 - Go to Step 8  -
7 Replace the mirror switch. Refer to Power Mirror Switch Replacement .
Did you complete the replacement?		 - Go to Step 8  -
8
  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
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