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Pump Circuit Failure: Testing

  1. Turn the ignition off. Turn the ignition on. Monitor the pump motor for continuous operation. Is the pump motor running continuously? Yes: Replace the Controller Anti-Lock Brake. See CONTROLLER ANTI-LOCK BRAKE (CAB)  . Perform ABS VERIFICATION TEST VER-1  . No: Go to next step.
  2. Turn the ignition on. With the DRBIII(R), read DTC's. With the DRBIII(R), erase DTC's. Turn the ignition off. Turn the ignition on. With the DRBIII(R), actuate the ABS pump motor. Did the pump motor operate when actuated? Yes: Go to next step. No: Go to step  4 .
  3. Turn the ignition off. Visually inspect the related wiring harness. Look for any chafed, pierced, pinched, or partially broken wires. Visually inspect the related wire harness connectors. Look for broken, bent, pushed out, or corroded terminals. Refer to any hotline information or Technical Service Bulletins that may apply. Were any problems found? Yes: Repair as necessary. Perform ABS VERIFICATION TEST VER-1  . No: Replace the Controller Anti-Lock Brake. See CONTROLLER ANTI-LOCK BRAKE (CAB)  . Perform ABS VERIFICATION TEST VER-1  .
  4. Check the short wiring harness between the ABS pump and the CAB. Check for disconnect and damage. Is the harness disconnected or damaged? Yes: Reconnect or repair the pump harness as necessary. Perform ABS VERIFICATION TEST VER-1  . No: Go to next step.
  5. Disconnect the CAB end of the short CAB/pump motor wiring harness. Check for disconnect and damage. Using jumper wires, connect 12 volts and ground to the pump motor connector. Does the pump motor run? Yes: Go to next step. No: Replace the Hydraulic Control Unit/Pump Motor assembly. See HCU (HYDRAULIC CONTROL UNIT)  . Perform ABS VERIFICATION TEST VER-1  .
  6. Turn the ignition off. Disconnect the CAB connector. Check connector and clean or repair as necessary. Turn the ignition on. Using a 12-volt test light connected to ground, check the pump motor fused B+ circuit. Does the test light illuminate brightly? Yes: Go to next step. No: Repair the fused B(+) circuit for an open. Perform ABS VERIFICATION TEST VER-1  .
  7. Turn the ignition off. Disconnect CAB connector. Check connector and clean or repair as necessary. Measure the resistance of the CAB ground circuits. Is the resistance below 1.0 ohm? Yes: Go to next step. No: Repair the ground circuit for an open. Perform ABS VERIFICATION TEST VER-1  .
  8. Turn the ignition on. With the DRBIII(R), enable pump motor actuation. Pump motor may not operate, but voltage will be applied. Measure the voltage drop across the ABS ground circuit connection, with pump motor actuation enabled. Is the voltage below 0.1 volt? Yes: Go to next step. No: Repair the ground circuit for high resistance. Perform ABS VERIFICATION TEST VER-1  .
  9. If there are no possible causes remaining, replace the Hydraulic Control Unit/Pump Motor assembly. See HCU (HYDRAULIC CONTROL UNIT)  . Perform ABS VERIFICATION TEST VER-1  .
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