# 12-06 Hydraulic Brake Backup Pump Verification

SAFETY PRECAUTIONS

  • Turn the start switch to the “OFF” position

  • Set the parking brake

  • Place wheel chocks around the tires.

PROCEDURE

  1. Confirm the hydraulic fluid level is correct in the hydraulic fluid reservoir.

  2. Locate the brake booster and visually ensure there is no leak or apparent damage.

  3. Locate the master-cylinder brake fluid reservoir and visually ensure there is no leak.

  4. Check the brake fluid level in the master cylinder reservoir. Add DOT3 brake fluid, if necessary.

Figure 1 – Brake module system components
Figure 1 – Brake module system components

  1. Turn the start switch to the ‘’OFF’’ position.
  1. Press the brake pedal and listen for the brake booster backup pump to turn on, the backup pump noise pitch will change as the pedal is pressed harder.

  2. Keep the brake pedal depressed for all the other steps.

  3. Turn the start switch to the ‘’ON/12V’’ position. The backup pump must keep running.

  4. Turn the start switch to the ‘’START’’ position long enough to activate the high–voltage (HV) circuit. After a few seconds, the backup pump should turn off as soon as the HV circuit powers the HV hydraulic pump.

  5. Keep the brake pedal depressed and turn the start switch to the “OFF” position. After a few seconds, the backup pump must restart as soon as the HV circuit is deactivated.

  6. Remove your feet from the brake pedal.