2008 GMC Sierra 2500 HD Brake Service (ONLINE REPAIR MANUALS)

Height Sensing Proportioning Valve

The height sensing proportioning valve must be adjusted whenever the valve and/or linkage is disassembled or removed for service. In addition, adjustment should be inspected if excessive front wheel lock-up is experienced with a lower than desired brake application rate when vehicle is at or near maximum GVWR.

• Raise and support vehicle, leave wheels on and allow axle to hang freely.
• Remove lever retaining nut and disconnect lever from valve shaft, Fig. .
• Rotate valve shaft to permit installation of correct adjustment gauge, Fig. , ensure D shaped hol...

Vue

Removal

• Raise and support vehicle.
• Mark relationship of drum to hub.
• Remove and discard retaining clip.
• Remove brake drum. If brake drum does not come off easily, proceed as follows:
• Loosen parking brake cable.
• Remove backing plate access hole plug.
• Disengage self adjuster by inserting suitable flat-bladed tool through backing plate access hole.
• Loosen adjuster screw by inserting another flat-bladed tool through access hole .
• Install access hole plug.
• Apply small amount of penetrating oil around brake drum center hole.
• Remove brake drum.
• Disengage adjuster spring hook end from tab on adjus...

Service Brake

The following procedure has been revised by a technical service bulletin.

These brakes have self-adjusting shoe mechanisms that ensure correct lining-to-drum clearances at all times. The automatic adjusters operate only when the brakes are applied as the vehicle is moving rearward or when the vehicle comes to an uphill stop.

Although the brakes are self-adjusting, an initial adjustment is required after the brake shoes have been relined or replaced, or when the length of the adjusting screw has been changed during some other service operation.

Frequent usage of an automati...

Service Brake

The following procedure has been revised by a technical service bulletin.

These brakes have self-adjusting shoe mechanisms that ensure correct lining-to-drum clearances at all times. The automatic adjusters operate only when the brakes are applied as the vehicle is moving rearward or when the vehicle comes to an uphill stop.

Although the brakes are self-adjusting, an initial adjustment is required after the brake shoes have been relined or replaced, or when the length of the adjusting screw has been changed during some other service operation.

Frequent usage of an automati...

Hybrid Battery Service

Disconnect

Before working on any high voltage system, be sure to wear the following Personal Protection Equipment: Safety glasses with appropriate side shields when within 50 feet of the vehicle, either indoors or outdoors. Certified and up-to-date Class "0" Insulation gloves rated at 1000 volts with leather protectors. Visually and functionally inspect the gloves before use. Wear the Insulation gloves at all times when working with the high voltage battery assembly, whether the system is energized or not. Failure to follow the procedure exactly as written may res...

Brake System Bleed

ABS Automated Bleed

The base hydraulic brake system must be bled before performing this automated bleeding procedure.

• Connect a suitable scan tool to Data Link Connector (DLC).
• Start engine and allow engine to idle.
• Follow instructions on scan tool to access automated bleed procedure.
• Apply brake pedal when instructed by scan tool.
• Turn ignition off and remove scan tool from vehicle.
• Fill brake master cylinder reservoir to maximum fill level with brake fluid from a clean, sealed brake fluid container.
• Bleed hydraulic brake system as outlined under "Hydraulic Brake System... "