Replacement Tires

Tire size is important for proper performance of the antilock brake system (ABS). Replacement tires should be the same size, load range, and construction as the original tires. Replace tires in axle sets and only with tires of the same tire performance criteria (TPC) specification number. Use of any other size or type may seriously affect the ABS operation.

IMPORTANT: There is no serviceable or removable electrically erasable programmable read only memory (EEPROM). The electronic brake control module (EBCM) must be replaced as an assembly.

The EBCM is attached to the hydraulic unit in the engine compartment. The controlling element of ABS 5.3 is a microprocessor-based EBCM. Inputs to the system include the 4 wheel speed sensors, the stop lamp switch, the ignition switch, and the unswitched battery voltage. There is an output to a bi-directional serial data link, located in pin K of the data link connector (DLC) for service diagnostic tools and assembly plant testing.

The EBCM monitors the speed of each wheel. If any wheel begins to approach lockup and the brake switch is closed, brake pedal depressed, the EBCM controls the solenoids to reduce brake pressure to the wheel approaching lockup. Once the wheel regains traction, brake pressure is increased until the wheel again begins to approach lockup. This cycle repeats until either the vehicle comes to a stop, the brake pedal is released, or no wheels approach lockup.

Additionally, the EBCM monitors itself, each input, except the serial data link, and each output for proper operation. If it detects any system malfunction, the EBCM will store a DTC in nonvolatile memory (EEPROM). Diagnostic trouble codes (DTCs) will not disappear if the battery is disconnected.