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Chevrolet Silverado / GMC Sierra. Manual - part 2802
Fig. 4: View Of Trailer Brake Control Module & Bolts
Courtesy of GENERAL MOTORS CORP.
Callout
Component Name
Preliminary Procedures
1. Turn the ignition switch to the OFF position.
2. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle .
1
Trailer Brake Control Module Bolt (Qty: 3)
Procedure:
Loosen, but do not remove the bolts. It is not necessary to completely remove
the bolts.
Tighten: 9 N.m (80 lb in)
NOTE:
Refer to Fastener Notice .
Trailer Brake Control Module
Procedure
2008 Chevrolet Silverado 1500
2008 BRAKES Trailer Brake Controls - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
TRAILER BRAKE CONTROL RELAY REPLACEMENT
Fig. 5: View Of Trailer Brake Control Relay, Electrical Connector & Bolts
Courtesy of GENERAL MOTORS CORP.
2
1. Disconnect the electrical connector.
2. Slide the module upward to remove.
3. If installing a new trailer brake control module, program the module.
Refer to Control Module References .
Callout
Component Name
Preliminary Procedures
1. Turn the ignition switch to the OFF position.
2. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle .
1
Trailer Brake Control Relay Electrical Connector
Procedure:
Disconnect the electrical connector.
Trailer Brake Control Relay Bolt (Qty: 2)
NOTE:
Refer to Fastener Notice .
2008 Chevrolet Silverado 1500
2008 BRAKES Trailer Brake Controls - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
DESCRIPTION AND OPERATION
TRAILER BRAKE CONTROLS DESCRIPTION AND OPERATION
This vehicle may be equipped with a Trailer Brake Control (TBCM) system for electric trailer
brakes. The power output to the trailer brakes is based on the amount of brake pressure being
applied in the vehicle's brake system. The available power output to the trailer brakes can be
adjusted to a wide range of trailering situations.
The vehicle is equipped with the following trailer braking components:
Manual Trailer Brake Apply
Trailer Gain Adjustment
2
Procedure:
Loosen, but do not remove the bolts. It is not necessary to completely remove
the bolts.
Tighten: 9 N.m (80 lb in)
3
Trailer Brake Control Relay
Procedure:
Slide the relay upward to remove.
IMPORTANT: Connecting a trailer that is not compatible with the ITBC system
may result in reduced or complete loss of trailer braking. There
may be an increase in stopping distance or trailer instability
which could result in personal injury or damage to your vehicle,
trailer, or other property. An aftermarket controller may be
available for use with trailers with surge, air or electric-over-
hydraulic trailer brake systems. To determine the type of brakes
on your trailer and the availability of controllers, check with your
trailer manufacturer or dealer.
IMPORTANT: If your vehicle is equipped with an ITBC, the blunt cuts exist, but
are not connected further in the harness. If you install an
aftermarket trailer brake controller, the ITBC must be
disconnected. Do not power both ITBC and aftermarket
controllers to control the trailer brakes at the same time.
2008 Chevrolet Silverado 1500
2008 BRAKES Trailer Brake Controls - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
Trailer Brake Control Panel
Trailer Brake DIC Display
Manual Trailer Brake Apply
The Manual Trailer Brake Apply Lever is located on the Trailer Brake Control Panel, and is used
to apply the trailer's electric brakes independent of your vehicle's brakes. This lever is used in the
Trailer Gain Adjustment Procedure to properly adjust the power output to the trailer brakes.
Sliding the lever to the left will apply only the trailer brakes. The power output to the trailer is
indicated in the Trailer Brake Display Page in the DIC. If your vehicle's service brakes are
applied while using the Manual Trailer Brake Apply Lever, the trailer output power will be the
greater of the two.
The trailer and the vehicle's brake lamps will come on when either vehicle braking or manual
trailer brakes are applied.
Trailer Gain Adjustment
Trailer Gain should be set for a specific trailering condition, and must be adjusted any time
vehicle loading, trailer loading or road surface conditions change.
Setting the Trailer Gain properly is needed for the best trailer stopping performance. A trailer
that is over-gained may result in locked trailer brakes. A trailer that is under-gained may result in
not enough trailer braking. Both of these conditions may result in poorer stopping and stability of
the vehicle and trailer.
After the electrical connection is made to a trailer equipped with electric brakes, the TRAILER
CONNECTED message will be momentarily displayed on the DIC. The Trailer Brake Display
Page will appear on the DIC showing TRAILER GAIN and OUTPUT, after all vehicle related
service messages are acknowledged by the driver. The dashed lines in the TRAILER OUTPUT
display signifies a disconnected trailer or TBCM fault condition, and will disappear only when
the TBCM fault condition is not present.
Trailer Gain Adjustment
Adjust trailer gain in 0.5 step increments up to 10 gain setting by using the gain adjustment
+/- buttons on the trailer brake control panel switch. Pressing and holding a gain button will
cause the trailer gain to continuously increment or decrement. To turn the output to the
trailer off, set the gain to zero.
Drive the tow vehicle and trailer combination on a level road surface representative of the
towing condition, and free of traffic at approximately 32-40 km/h (20-25 mph) and fully
2008 Chevrolet Silverado 1500
2008 BRAKES Trailer Brake Controls - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
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