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Home >> Mitsubishi >> 2004 >> Montero XLS >> Repair and Diagnosis >> Brakes >> Mechanical - Hydraulic >> Hydraulic Brake Booster >> Diagnostic Tests >> DTC 55: Pump Motor Circuit (Pump Motor Energized Abnormally For Long Period) >> Diagnosis & Repair

Diagnosis & Repair

NOTE: For component location and connector identification, see Figure .
  1. Remove motor relay "A". If pump motor stops, go to step  15 . If pump motor does not stop, go to next step.
  2. Remove motor relay "B". If pump motor stops, go to step  15 . If pump motor does not stop, go to next step.
  3. Disconnect HBB connector B-18. Measure voltage between ground and terminal No. 31. Voltage should be zero volts. If voltage is zero volts, go to step  5 . If voltage is not zero volts, go to next step.
  4. Check wire between motor relay "A" connector B-53X terminal No. 4 and HBB connector B-18 terminal No. 31. If problem is found, repair as necessary, then go to step  15 . If problem is not found, go to step  15 .
  5. Disconnect HBB connector B-17. Measure voltage between ground and terminal No. 2. Voltage should be zero volts. If voltage is zero volts, go to step  7 . If voltage is not zero volts, go to next step.
  6. Check wire between motor relay "B" connector B-55X terminal No. 5 and HBB connector B-17 terminal No. 2. If problem is found, repair as necessary, then go to step  15 . If problem is not found, go to step  15 .
  7. Check wire between motor relay "A" connector B-53X terminal No. 1 and M-ASTC-ECU connector E-120 terminal No. 48. Also, check wire between motor relay "B" connector B-54X terminal No. 1 and M-ASTC-ECU connector E-119 terminal No. 24. If problem is found, repair as necessary, then go to step  15 . If problem is not found, go to next step.
  8. Disconnect M-ASTC-ECU connector E-119. Measure resistance between ground and terminal No. 11. Resistance should be less than 2 ohms. If resistance is less than 2 ohms, go to next step. If resistance is not less than 2 ohms, go to step  12 .
  9. Check wire between HBB connector B-18 terminal No. 35 and M-ASTC-ECU connector E-119 terminal No. 11. If problem is found, repair as necessary, then go to step  15 . If problem is not found, go to next step.
  10. With ignition off, depress brake pedal repeatedly more than 40 times until pedal depressing force feels heavy. Disconnect HBB connector B-18. Measure resistance between terminals No. 33 and 35 (component side). Resistance should be about 1000 ohms. If resistance is about 1000 ohms, go to next step. If resistance is not about 1000 ohms, replace master cylinder and hydraulic unit assembly, then go to step  15 .
  11. Check pump motor operation. If pump motor operates, go to step  14 . If pump motor does not operate, go to next step.
  12. Clear DTC memory. Recheck for DTC. If DTC 55 resets, go to next step. If DTC 55 does not reset, diagnosis and repair procedure is complete.
  13. Check wire between HBB connector B-17 terminal No. 4 and M-ASTC-ECU connector E-119 terminal No. 25. If problem is found, repair as necessary, then go to step  15 . If problem is not found, go to next step.
  14. Clear DTC memory. Recheck for DTC. If DTC 55 is set, replace M-ASTC-ECU, then go to next step. If DTC 55 is not set, it can be assumed that this malfunction is intermittent.
  15. Clear DTC memory. Recheck for DTC. If DTC 55 is set, go to step  1 . If DTC 55 is not set, repair is complete.
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