Safety Warning

DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.

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HOMESERVICE MANUALSCHEVROLET2008CHEVY EXPRESS G3500, VAN PASSENGER EXTENDEDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 767 (HYDRAULIC BRAKE SYSTEM)REPAIR INSTRUCTIONSBRAKE MASTER CYLINDER PRIMARY PISTON POSITION SENSOR REPLACEMENTINSTALLATION PROCEDURE

2008 Chevrolet Chevy Express G3500, Van Passenger Extended

Installation Procedure

2008 Chevrolet Chevy Express G3500, Van Passenger ExtendedSECTION Installation Procedure

WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2011 GMC Yukon XL, 2011 GMC Yukon, 2011 Chevrolet Tahoe, 2011 Chevrolet Suburban, and 2011 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: Primary Piston Position Sensor

Courtesy of GENERAL MOTORS CORP.

Install the BMC primary piston position sensor (2).

CAUTION:

Refer to Fastener Caution .

Install the 2 primary piston position sensor screws (1) and tighten to 10 N.m (89 lb in).
Connect the primary piston position sensor electrical connector.
Inspect the battery state of charge. Refer to Battery Inspection/Test .
If necessary, connect a battery charger to the 12V battery. Refer to Battery Charging .
Install a scan tool to the vehicle.

NOTE:

The ignition switch must remain in the ON position with the engine OFF during this procedure.

Turn the ignition ON with the engine OFF.
Using the scan tool, perform the following steps:
1. Select Diagnostics
2. Select the appropriate vehicle information
3. Select Chassis
4. Select Electronic Brake Control Module (EBCM)
5. Select Module Setup
6. Select BMC Primary Piston Position Relearn and follow the instructions on the scan tool

RENDER: 1.0x

NO RELATED

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.
• Brakes feel soft, pull hard to one side, or make grinding noises.
• The engine overheats, stalls repeatedly, or misfires under load.
• You are missing required tools, torque specs, or safe lifting equipment.
• You are not confident in the next step or safety outcome.