Drivetrain - 'Service 4WD' Indicator ON/DTC B2725 Set
File In Section: 04 - Driveline AxleBulletin No.: 02-04-21-002A
Date: February, 2003
TECHNICAL
Subject:
"Service 4WD" Indicator Illuminated, DTC B2725 Set, Transfer Case Selector Switch is in One Position - Indicator Lamp Indicates Another Range is Selected (Replace Transfer Case Shift Control Switch)
Models:
2002-2003 Chevrolet TrailBlazer, TrailBlazer EXT
2002-2003 GMC Envoy, Envoy XL with Four-Wheel Drive
This bulletin is being revised to change the part number, service procedures and a labor operation number. Please discard Corporate Bulletin Number 02-04-21-002 (Section 04 - Driveline Axle).
Condition
Some customers may comment that the Service 4WD indicator is illuminated or that the Indicator lamp is illuminated for a range other than the one selected with the selector switch. Upon investigation, the technician may find a DTC B2725.
Cause
The condition may be due to the transfer case shift control switch.
Correction
Replace the transfer case shift control switch using the applicable procedure below for the vehicle being serviced.
GMC Envoy, Envoy XL
Notice:
Trying to remove the transfer case control switch from the instrument panel (IP) trim panel without releasing the retainers will damage the IP trim panel. The switch cannot be removed without first removing the trim panel.
1. Remove the four screws that retain the center IP closeout to the bottom of the IP. The closeout is located just in front of the floor console assembly with two (2) screws on each side.
2. Gently disconnect the trim panel from the IP by grasping the rearward portion of the closeout and pull toward the door openings. With the panel wings spread away from the IP, gently pull the panel wings down toward the footwell area of the vehicle. The front edge of the trim panel will drop down, allowing access to the two (2) screws retaining the lower edge of the IP trim panel.
3. Place a clean shop cloth over the front edge of the console upper trim panel to protect against possible marring from the screwdriver.
4. Remove the two (2) screws.
5. Remove the center IP trim panel by gently pulling it toward the rear of the vehicle in order to release the retaining clips.
6. Disconnect the electrical connectors from the switch.
7. Depress the switch retainers and remove the switch.
8. Insert the new switch into the IP trim panel and reconnect the electrical connector.
9. Reinstall the IP trim and the two (2) retaining screws.
10. Reposition the closeout panel and install the four (4) retaining screws.
11. For 2002 vehicles produced prior to January 2002, verify that the vehicle contains the latest calibration for the automatic transfer case control module. The calibrations were available from Techline starting January 2002, on the TIS 2000 version TIS 01/2002 data update or later. Reprogram the automatic transfer case control module if necessary.
Chevrolet TrailBlazer, TrailBlazer EXT
Notice:
Trying to remove the transfer case control switch from the instrument panel (IP) trim panel without releasing the retainers will damage the IP trim panel. The switch cannot be removed without first removing the trim panel.
1. Remove the two (2) screws that retain the rear edge of the driver's side insulator to the IP.
2. Remove the two (2) screws that retain the bottom of the knee bolster to the IP.
3. Remove the two (2) screws that retain the top of the knee bolster to the IP.
4. Remove the four (4) screws that retain the IP bezel to the IP.
5. Separate the bezel from the IP enough to allow access to the transfer case control switch.
6. Disconnect the electrical connector and remove the switch.
7. Install the new switch and connect the electrical connector.
8. Reposition the IP bezel and install the four (4) retaining screws.
9. Reposition the knee bolster and install the four (4) retaining screws.
10. Reposition the insulator and install the two (2) retaining screws.
11. For 2002 vehicles produced prior to January 2002, verify that the vehicle contains the latest calibration for the automatic transfer case control module. The calibrations were available from Techline starting January 2002, on the TIS 2000 version TIS 01/2002 data update or later. Reprogram the automatic transfer case control module if necessary.
Parts Information
Parts are currently available from GMSPO.
Warranty Information
For vehicles repaired under warranty, use the table.
Disclaimer