Pretest Checks
NOTE:
Performing PRETEST CHECKS will identify relatively simple repairs and prepare vehicle for further diagnosis. Warning light faults are also identified and repaired using pretest checks. Perform pretest checks in order given unless specified otherwise.
- Underhood Checks (Electrical)
Check following items for good connection, condition, contamination and corrosion:- 35-pin ABS Electronic Control Module (ECM) connector.
- 14-pin Data Link Connector (DLC).
- 12-pin Hydraulic Control Unit (HCU) connector.
- 2-pin speed sensor connectors.
- Blown fuses. - 10-amp electronic ignition. - 15-amp stoplight. - 10-amp meter. - 20-amp anti-skid. - 30-amp anti-skid.
- Blown anti-lock warning light bulb.
- Damaged wiring harness.
- Loose or corroded connections.
- Underhood Checks (Mechanical)
Check for following items:- Low brake fluid.
- Damaged wheel speed sensor.
- Damaged hydraulic actuator assembly.
- Damaged brakeline(s).
- Damaged wheel bearing(s).
- Other Checks
Check hydraulic brakelines for air and fluid leaks. Check for problems in other areas that may affect anti-lock brake system, such as:- Suspension and steering components.
- Tire integrity and air pressure.
- Wheel bearings.
- Brake components that are common to all brake systems.
Check wiring harness for obvious signs of shorts, opens, bad connections or damage. If fault is not evident, determine symptom and proceed to symptom chart. See Fig 1 .