Brake Pad Inspection through Symptom List
Disc Brake Fastener Specifications
Fastener Tightening Specifications:
Disc Brake Component Specifications
Disc Brake Component Specifications:
Disc Brake Component Specifications (cont'd)
Disc Brake Component Specifications (cont'd):
page 5-74
Micrometer:
Disc Brakes
Diagnostic Information and Procedures
Diagnostic Starting Point - Disc Brakes
Begin the disc brake system diagnosis with Diagnostic Starting Point - Hydraulic Brakes in Hydraulic Brakes. The use of the Diagnostic Starting Point will lead to the identification of the correct procedure for diagnosing the system and where the procedure is located.
Brake Pad Inspection
Caution: Refer to Brake Dust Caution in Cautions and Notices.
^ Inspect the disc brake pads at regular intervals, or whenever the tire and wheel assemblies are removed from the vehicle.
^ If replacement is necessary, always replace disc brake pads in axle sets.
^ Inspect both edges of the disc brake pad friction surfaces (3). The highest rate of wear normally occurs at the trailing edge of the disc brake pads.
^ Inspect the thickness of the disc brake pads (3) in order to ensure that they have not worn prematurely. The disc brake pad wear should be approximately even per axle set.
^ Both front and rear disc brake pads have integral, audible wear sensors (1). When the disc brake pad wear reaches the minimum allowable thickness, the wear sensor contacts the disc brake rotor (2). The wear indicator will then produce an audible, high-pitched warning noise during wheel rotation.
^ Replace the disc brake pads when the friction surface (3) is worn to within 0.76 mm (0.030 in) of the mounting plates.
^ Remove the brake calipers and inspect the friction surfaces of the inner and outer disc brake pads to ensure that they are level. Place the disc brake pad friction surfaces together and measure the gap between the surfaces. If more than 0.13 mm (0.005 in) gap exists midway between the length of the disc brake pads, replace the disc brake pads.
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Apply threadlocker GM US P/N 12345493, Canada P/N 10953488, or equivalent to two-thirds of the threaded length of the lower caliper bracket bolts. Ensure that there are no gaps in the threadlocker along the length of the filled area of the bolts.
Allow the threadlocker to cure approximately ten minutes before installation.
Notice: Refer to Fastener Notice in Cautions and Notices.
2. Install the backing plate bolts.
Tighten
Tighten the backing plate bolts to 135 Nm (100 lb ft).
3. Install the park brake shoe. Refer to Park Brake Shoe Replacement.
4. Adjust the park brake shoe. Refer to Park Brake Adjustment (J55).
5. Install the hub and bearing assembly. Refer to Wheel Bearing/Hub Replacement - Rear (FE 1, FE3) or Wheel Bearing/Hub Replacement - Rear (FE7).
6. Install the brake rotor. Refer to Brake Rotor Replacement - Rear (Without (J55)) or Brake Rotor Replacement - Rear (J55).
7. Install the park brake cable to the mounting bracket until the locking tabs snap into place.
8. Install the park brake cable to the brake caliper lever.
9. Pull down on the front park brake cable and connect the intermediate cable from the connector.
10. Install the caliper and mounting bracket as an assembly. Refer to Brake Pads Replacement - Rear (J55) or Brake Pads Replacement - Rear (without J55).
11. Install the tire and wheel assembly. Refer to Tire and Wheel Removal and Installation in Tires and Wheels.
12. Lower vehicle.
Brake Rotor Assembled Lateral Runout (LRO) Correction
Important:
^ Brake rotor thickness variation MUST be checked BEFORE checking for assembled lateral runout (LRO). Thickness variation exceeding the maximum acceptable level can cause brake pulsation. Refer to Brake Rotor Thickness Variation Measurement.
^ Brake rotor assembled lateral runout (LRO) exceeding the maximum allowable specification can cause thickness variation to develop in the brake rotor over time, usually between 4 800-11 300 km (3,000-7,000 mi). Refer to Brake Rotor Assembled Lateral Runout (LRO) Measurement.
Review the following acceptable methods for brining the brake rotor assembled LRO to within specifications. Determine which method to use for the specific vehicle being repaired.
- Brake Rotor Assembled Lateral Runout (LRO) Correction - Indexing.
The indexing method of correcting assembled LRO is most effective when the LRO specification is only exceeded by a relatively small amount: 0.025-0.127 mm (0.001.005 in). Indexing is used to achieve the best possible match of high spots to low spots between related component.
- Brake Rotor Assembled Lateral Runout (LRO) Correction - Correction Plates.
The correction plate method of correcting assembled LRO involves the addition of a tap red plate between the brake rotor and the hub/axle flange. The correction plate method can be used to correct LRO that exceeds the specification by up to 0.23 mm (0.009 in).
- Brake Rotor Assembled Lateral Run put (LRO) Correction - On-Vehicle Lathe.
The on-vehicle brake. lathe method is used to bring the LRO to within specifications through compensating for LRO while refinishing the brake rotor.
If the assembled LRO cannot be corrected using these methods then other components must be suspected as causing and/or contributing to the LRO concern.
Brake Rotor Assembled Lateral Runout (LRO) Correction - Indexing
Tools Required
J 39544-KIT Torque-Limiting Socket Set, or equivalent
J 45101-100 Conical Brake Rotor Washers
Caution: Refer to Brake Dust Caution in Cautions and Notices.
Important:
^ Brake rotor thickness variation MUST be checked BEFORE checking for assembled lateral runout (LRO). Thickness variation exceeding the maximum acceptable level can cause brake pulsation. Refer to Brake Rotor Thickness Variation Measurement.
^ Brake rotor assembled lateral runout (LRO) exceeding the maximum allowable specification can cause thickness variation to develop in the brake rotor over time, usually between 4 800- 11 300 km (3,000-7,000 mi). Refer to Brake Rotor Assembled Lateral Runout (LRO) Measurement.
1. Remove the J45101-100 and the lug nuts that were installed during the assembled LRO measurement procedure.
2. Inspect the mating surface of the hub/axle flange and the brake rotor to ensure that there are no foreign particles or debris remaining.
3. Index the brake rotor in a different orientation to the hub/axle flange.
4. Hold the rotor firmly in place against the hub/axle flange and install one of the J45101-100 (1) and one lug nut (2) onto the upper-most wheel stud.
5. Continue to hold the rotor secure and tighten the lug nut firmly by hand.
6. Install the remaining J45101-100 and lug nuts onto the wheel studs and tighten the nuts firmly by hand in a star-pattern.
7. Using the J 39544-KIT or equivalent, tighten the lug nuts in a star-pattern to specification, in order to properly secure the rotor. Refer to Tire and Wheel Removal and Installation in Tires and Wheels.
8. Measure the assembled LRO of the brake rotor. Refer to Brake Rotor Assembled Lateral Runout (LRO) Measurement.
9 Compare the amount of change between this measurement and the original measurement.
10. If this measurement is within specifications, proceed to step 14.
11. If this measurement still exceeds specifications, repeat steps 1-9 until the best assembled LRO measurement is obtained.
12. Match mark the final location of the rotor to the wheel studs if the orientation is different than it was originally.
13. If the brake rotor assembled LRO measurement still exceeds the maximum allowable specification, refer to Brake Rotor Assembled Lateral Runout (LRO) Correction.
14. If the brake rotor assembled LRO is within specification, install the brake caliper and depress the brake pedal several times to secure the rotor in place before removing the J45101-100 and the lug nuts.
Brake Rotor Assembled Lateral Runout (LRO) Correction - Correction Plates
Tools Required
^ J 39544-KIT Torque-Limiting Socket Set, or equivalent
^ J 45101-100 Conical Brake Rotor Washers
Caution: Refer to Brake Dust Caution in Cautions and Notices.
Important:
^ Brake rotor thickness variation MUST be checked BEFORE checking for assembled lateral runout (LRO). Thickness variation exceeding the maximum acceptable level can cause brake pulsation. Refer to Brake Rotor Thickness Variation Measurement.
^ Brake rotor assembled lateral runout (LRO) exceeding the maximum allowable specification can cause thickness variation to develop in the brake rotor over time, usually between 4 800-11 300 km (3,00-7,000 mi). Refer to Brake Rotor Assembled Lateral Runout (LRO) Measurement.
1. Rotate the brake rotor to position the high spot identified and marked during the brake rotor assembled LRO measurement procedure, to face upward.
2. Remove the J 45101-100 and the lug nuts than were installed during the assembled LRO measurement procedure and/or the indexing correction procedure.
3. Inspect the mounting surface of the hub/axle flange and the brake rotor to ensure that there are no foreign particles or debris remaining.
4. Select the correction plate, following the manufacturer's instructions, which has a specification closest to the assembled LRO measurement.
For example: If the assembled LRO measurement was 0.076 mm (0.003 in), the 0.076 mm (0.003 in) correction plate would be used. If the measurement was 0.127 mm (0.005 in), the 0.152 mm (0.006 in) correction plate would be used.
5 Determine the positioning for the correction plate (1) using the high spot mark (3) made during the brake rotor assembled LRO measurement procedure.
Important:
^ Do NOT install used correction plates in an attempt to correct brake rotor assembled lateral runout (LRO).
^ Do NOT stack up, or install more than one correction plate onto one hub/axle flange location, in an attempt to correct brake rotor assembled LRO.
6. Install the correction plate (1) onto the hub/axle flange, with the V-shaped notch (2) orientated to align with the high spot mark (3), that was positioned to face upward.
7. Install the brake rotor to the hub/axle flange. Use the matchmark made prior to removal for proper orientation to the flange.
8. Hold the rotor firmly in place against the hub/axle flange and install one of the J45101-100 (1) and one lug nut (2) onto the upper-most wheel stud.
9. Continue to hold the rotor secure and tighten the lug nut firmly by hand.
10. Install the remaining J45101-100 and lug nuts onto the wheel studs and tighten the nuts firmly by hand in a star-pattern.
11. Using the J 39544-KIT or equivalent, tighten the lug nuts in a star-pattern to specification, in order to properly secure the rotor. Refer to Tire and Wheel Removal and Installation in Tires and Wheels.
12. Measure the assembled LRO of the brake rotor. Refer to Brake Rotor Assembled Lateral Runout (LRO) Measurement.
13. If the brake rotor assembled LRO measurement still exceeds the maximum allowable specification, refer to Brake Rotor Assembled Lateral Runout (LRO) Correction.
14. If the brake rotor assembled LRO measurement is within specification, install the brake caliper and depress the brake pedal several times to secure the rotor in place before removing the J45101-100 and the lug nuts.
Brake Rotor Assembled Lateral Runout (LRO) Correction - On-Vehicle Lathe
Tools Required
J45101-100 Conical Brake Rotor Washers
Caution: Refer to Brake Dust Caution In Cautions and Notices.
Important:
^ Brake rotor thickness variation MUST be checked BEFORE checking for assembled lateral runout (LRO). Thickness variation exceeding the maximum acceptable level can cause brake pulsation. Refer to Brake Rotor Thickness Variation Measurement.
^ Brake rotor assembled lateral runout (LRO) exceeding the maximum allowable specification can cause thickness variation to develop in the brake rotor over time, usually between 4 800-11 300 km (3,000-7,000 ml). Refer to Brake Rotor Assembled Lateral Runout (LRO) Measurement.
1. Ensure that the caliper and caliper bracket than are already being supported, are clear from contacting any rotating components, such as the brake rotor.
2. Remove the J45101-100 and the lug nuts that were installed during the assembled LRO measurement procedure and/or the indexing correction procedure.
3. Inspect the mounting surface of the hub/axle flange and the brake rotor to ensure that there are no foreign particles or debris remaining.
4. Set up the lathe, following the manufacturer's instructions.
5. Refinish the brake rotor, following the brake lathe manufacturer's instructions.
6. After each successive cut, inspect the brake rotor thickness. Refer to Brake Rotor Thickness Measurement.
7. If at any time the brake rotor exceeds the minimum allowable thickness after refinish specification, the brake rotor must be replaced After replacing the rotor, proceed to step 10.
8. After refinishing the brake rotor, use the following procedure in order to obtain the desired non-directional finish:
8.1. Follow the brake lathe manufacturer's recommended speed setting for applying a non-directional finish
8.2. Using moderate pressure, apply the non-directional finish:
^ If the lathe is equipped with a non-directional finishing tool, apply the finish with 120 grit aluminum oxide sandpaper
^ If the lathe is not equipped with a non-directional finishing tool, apply the finish with a sanding block and 150 grit aluminum oxide sandpaper
8.3. After applying a non-directional finish, clean each friction surface of the brake rotor with denatured alcohol, or an equivalent approved brake cleaner
9. Remove the lathe from the vehicle.
10. Measure the assembled LRO of the brake rotor. Refer to Brake Rotor Assembled Lateral Runout (LRO) Measurement.
11. If the brake rotor assembled LRO measurement still exceeds the maximum allowable specification, refer to Brake Rotor Assembled Lateral Runout (LRO) Correction.
12. If the brake rotor assembled LRO is within specification, install the brake caliper and depress the brake pedal several times to secure the rotor in place before removing the J 45101-100 and the lug nuts.
Brake Rotor Refinishing
Tools Required
^ J 41013 Rotor Resurfacing Kit
^ J 42450-A Wheel Hub Resurfacing Kit
Caution: Refer to Brake Dust Caution in Cautions and Notices.
Important:
^ The disc brake rotors do not require refinishing as part of routine brake system service. New disc brake rotors do not require refinishing.
Do not refinish disc brake rotors in an attempt to correct the following conditions:
- Brake system noise - squeal, growl, groan
- Uneven and/or premature disc brake pad wear
- Superficial or cosmetic corrosion/rust of the disc brake rotor friction surface
- Scoring of the disc brake rotor friction surface less than the maximum allowable specification
^ Before refinishing a brake rotor, the rotor MUST first be checked for adequate thickness to allow the rotor to be refinished and remain above the minimum allowable thickness after refinish specification. Refer to Brake Rotor Thickness Measurement.
^ Disc brake rotors should only be refinished if they have adequate thickness to be refinished and if one or more of the following conditions exist:
- Thickness variation in excess of the maximum allowable specification
- Excessive corrosion/rust and/or pitting
- Cracks and/or heat spots
- Excessive blueing discoloration
- Scoring of the disc brake rotor surface in excess of the maximum allowable specification
^ Disc brake rotors may need to be refinished as part of the process for correcting brake rotor assembled lateral runout (LRO) that exceeds the maximum allowable specification.
Special Tools and Equipment
Special Tools And Equipment:
Special Tools And Equipment:
Park Brake Specifications
Fastener Tightening Specifications:
3. Install the park brake pedal assembly to the mounting studs.
4. Install the park brake pedal assembly mounting nuts (1, 2).
Tighten
Tighten the park brake pedal assembly mounting nuts to 24 N.m (18 lb ft).
5. Connect the electrical connector to the park brake warning lamp switch.
6. Install the left knee bolster. Refer to Knee Bolster Replacement - Left (Without UV2) or knee Bolster Replacement - Left (UV2) in Instrument Panel, Gages, and Console.
7. Install the left closeout/insulator. Refer to Closeout/insulator Panel Replacement - Left in Instrument Panel, Gages, and Console.
8. Install the left carpet retainer. Refer to Carpet Retainer Replacement - Front in Interior Trim.
Park Brake Cable Replacement - Front
Tools required
J 37043 Parking Brake Cable Release Tool
Removal Procedure
1. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
2. Ensure the park brake pedal is in the full returned position.
3. Pull down on the front cable in relieve tension on the cable.
4. Remove the cable (3) from the cable connector (1).
5. Using J 37043 depress the park brake cable retainer.
6. Remove the park brake cable from the park brake cable support.
Electronic Brake Control Module (EBCM)
Electronic Brake Control Module (EBCM):
DTC C1277 or P1571
Test Steps 1 - 7:
Test Steps 1 - 5:
Test Steps 6 - 7:
DTC C1295
Circuit Description
The EBCM sources 5 volts on the stop lamp switch signal circuit when the stop lamp switch is inactive. The voltage is supplied a ground path through the stop lamp bulbs.
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
The stop lamp switch input voltage is between 2.1 volts and 5.3 volts for 2 seconds.
Action Taken When the DTC Sets
The EBCM disables the TCS for the duration of the ignition cycle.
^ The Traction Control indicator turns ON.
^ The ABS remains functional.
Conditions for Clearing the DTC
^ The condition for the DTC is no longer present (the DTC is not current) and you used the scan tool Clear DTC function.
^ The condition for the DTC is no longer present (the DTC is not current) and you used the On-Board Diagnostics Clear DTC function.
^ The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.
Diagnostic Aids
Possible causes of this DTC are the following conditions:
^ A signal circuit of the stop lamp switch is open.
^ The stop lamp switch is misadjusted.
^ Verify proper stop lamp switch operation using the data list of the scan tool. As the brake is applied, the data list displays the stop lamp switch ON within 2.54 cm (1 in) of travel.
^ All brake lamps are open.
^ All brake lamp grounds are open.
^ Circuit has a wiring problem terminal corrosion, or poor connections.
^ Loose or corroded EBCM ground or PCM ground.
^ An internal EBCM problem.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
3. This DTC detects an open stop lamp switch signal circuit from the stoplamp side of the splice pack to the EBCM.
4. Verifies that the stop lamps are operating properly.
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Symptoms - Antilock Brake System
Important: The following steps must be completed before using the symptom tables.
1. Perform the Diagnostic System Check-ABS before using the Symptom Tables in order to verity that all of the following are true:
^ There are no DTCs set.
^ The control module(s) can communicate via the serial data link.
2. Review the system operation in order to yourself with the system functions. Refer to AB Description and Operation.
Visual/physical Inspection
^ Inspect for aftermarket devices which could affect the operation of the antilock brake system. Refer to Checking Aftermarket Accessories in Wiring Systems.
^ Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.
^ Inspect the master cylinder reservoir for the proper brake fluid level.
Intermittent
Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent and Poor Connections in Wiring Systems.
Symptom List
Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom:
^ ABS Indicator Always On
^ ABS Indicator Inoperative
^ Traction Control Indicator Always On
^ Traction Control Indicator Inoperative
^ Traction Off Indicator Inoperative
^ Vehicle Stability Enhancement System Inoperative
^ Vehicle Stability Enhancement System Unwanted Activation
^ Vehicle Stability Enhancement System Excessive Brake Pulsation