Chevrolet Silverado / GMC Sierra. Service manual — part 721

open/high resistance. If the circuit tests normal, replace the EBCM.

If greater than 5.2 volts, test the 5-volt reference circuit for a short to voltage. If the
circuit tests normal, replace the EBCM.

4. Test for 4.5-5.3 volts between the 5-volt reference circuit terminal B and the signal circuit

terminal C.

If less than the specified range, test the signal circuit for an open/high resistance. If the
circuit tests normal, replace the EBCM.

If greater specified range, test the signal circuit for a short to voltage. If the circuit
tests normal, replace the EBCM.

5. Install a 3A fused jumper wire at the signal circuit terminal C. Toggle the jumper wire

between the low reference circuit terminal and the 5-volt reference circuit terminal B.
Verify the scan tool Brake Pressure Sensor Input parameter toggles between 0.2-3.2 volts.

If the specified parameter, does not toggle between the minimum and maximum values
test the signal circuit for a short to voltage, short to ground or an open/high resistance.
If the circuit tests normal, replace the EBCM.

6. If all circuits test normal, test or replace the brake booster vacuum sensor.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for EBCM replacement, setup, and programming

SYMPTOMS - ANTILOCK BRAKE SYSTEM

IMPORTANT: The following steps must be completed before using the symptom

tables.

1. Perform the ABS Diagnostic System Check before using the

symptom tables in order to verify that all of the following are
true:

There are no DTCs set.

The control modules can communicate via the serial
data link.

2. Review the system description and operation in order to

familiarize yourself with the system functions. Refer to ABS
Description and Operation (With JL4) or ABS Description and
Operation (Without JL4).

2008 Chevrolet Silverado 1500

2008 BRAKES Antilock Brake System - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

Visual/Physical Inspection

Inspect for aftermarket devices which could affect the operation of the ABS. Refer to
Checking Aftermarket Accessories .

Inspect the easily accessible or visible system components, for obvious damage or
conditions, which could cause the symptom.

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer Testing
for Intermittent Conditions and Poor Connections .

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the
symptom:

ABS INDICATOR MALFUNCTION

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Circuit/System Description

The instrument panel cluster (IPC) illuminates the Antilock Brake System (ABS) indicator by
supplying ground to the lamp. The electronic brake control module (EBCM) sends a serial data
messages to the IPC, in order to command the indicator ON or OFF.

Reference Information

Schematic Reference

Antilock Brake System Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

2008 Chevrolet Silverado 1500

2008 BRAKES Antilock Brake System - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

ABS Description and Operation (With JL4) or ABS Description and Operation (Without
JL4)

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for Scan Tool Information

Circuit Verification

Ignition ON, observe the ABS indicator to turn ON then OFF during the IPC bulb test.

Circuit/System Testing

1. Ignition On, with a scan tool command the Scan Tool IPC display test ON and OFF. The

ABS indicator should turn ON and OFF.

If the ABS warning lamp does not turn ON and OFF, replace the IPC.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for EBCM or IPC replacement, setup, and programming

STABILITRAK INDICATOR MALFUNCTION

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Circuit Description

The instrument panel cluster (IPC) illuminates the stabilitrak indicator during the IPC bulb check

2008 Chevrolet Silverado 1500

2008 BRAKES Antilock Brake System - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

or when the electronic brake control module (EBCM) sends a serial data message to the IPC
commanding the indicator ON.

Reference Information

Schematic Reference

Antilock Brake System Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

ABS Description and Operation (With JL4) or ABS Description and Operation (Without
JL4)

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for Scan Tool Information

Circuit Verification

Ignition ON, observe the Stabilitrak indicator to turn ON then OFF during the IPC bulb test.

Circuit/System Testing

1. Ignition On, with a scan tool command the Scan Tool IPC display test ON and OFF. The

Stabilitrak indicator should turn ON and OFF.

If the Stabilitrak indicator does not turn ON and OFF, replace the IPC.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

2008 Chevrolet Silverado 1500

2008 BRAKES Antilock Brake System - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado