DTC C1073: Faulty motor drive circuit: Diagnosis

WARNING: This page is about a different car, the 2008 Mitsubishi Lancer. However, it is still accessible from the selected car via links, so may be relevant.

Required Special Tools:

MB991958 Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: Vehicle Communication Interface (V.C.I.)
- MB991827 M.U.T.-III USB Cable
- MB991910 M.U.T.-III Main Harness A
MB991997: ASC check harness

STEP 1. Using scan tool MB991958, diagnose the CAN bus lines.
Using scan tool MB991958, diagnose the CAN bus lines.

Q: Is the check result normal?

YES : Go to Step 3.

NO : Repair the CAN bus lines. (Refer to TROUBLESHOOTING .) After repairing the CAN bus line, go to Step 2.
STEP 2. DTC recheck after repairing the CAN bus line
Q: Is DTC C1073 set?

YES : Go to Step 3.

NO : The procedure is complete.
STEP 3. Fusible link check: Check the fusible link No. 26.
Q: Is the check result normal?

YES : Go to Step 4.

NO : Replace the fusible link No.26.
STEP 4. Battery check
Refer to BATTERY TEST .

Q: Is the battery in good condition?

YES : Go to Step 5.

NO : Charge or replace the battery.
STEP 5. Charging system check
Refer to OUTPUT CURRENT TEST .

Q: Is the charging system in good condition?

YES : Go to Step 6.

NO : Repair or replace the charging system component(s).
STEP 6. Voltage measurement at the A-05 ASC-ECU connector
1. Disconnect the connector, connect the ASC check harness (Special tool: MB991997) to the wiring harness-side connector, and measure the voltage at the special tool connector side.
  NOTE: Do not connect the special tool to ASC-ECU.
2. Measure the voltage between the terminal No. 1 and the body ground.
  
  Fig 1: Measuring Voltage Between Terminal No. 1 And Body Ground
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
  
  OK: System voltage
Q: Is the check result normal?

YES : Go to Step 8.

NO : Go to Step 7.
STEP 7. Connector check: A-05 ASC-ECU connector
Q: Is the check result normal?

YES : An open or short circuit may be present in the pump motor power supply circuit. Repair the wiring harness between A-05 ASC-ECU connector terminal No. 1 and the fusible link No. 26.

NO : Repair the defective connector.
STEP 8. Resistance measurement at A-05 ASC-ECU connector
1. Disconnect the connector, connect the ASC check harness (Special tool: MB991997) to the wiring harness-side connector, and measure the voltage at the special tool connector side.
  NOTE: Do not connect the special tool to ASC-ECU.
2. Measure the resistance between the terminal No. 16 and the body ground as well as between the terminal No. 47 and the body ground.
  
  Fig 2: Measuring Resistance Between Terminal No. 16 And Body Ground
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
  
  OK: Continuity exists (2 Ω or less)
Q: Is the check result normal?

YES : Go to Step 10.

NO : Go to Step 9.
STEP 9. Connector check: A-05 ASC-ECU connector
Q: Is the check result normal?

YES : An open circuit may be present in the ground circuit. Repair the wiring harness between A-05 ASC-ECU connector terminal No. 16 and the ground as well as between A-05 ASC-ECU connector terminal No. 47 and the ground.

NO : Repair the defective connector.
STEP 10. Check whether the DTC is reset.
1. Erase the diagnostic trouble code.
2. Drive the vehicle at 12mph (20 km/h) or more.
  NOTE: The ABS warning light does not turn OFF in some cases unless the vehicle runs at 12mph (20 km/h) or higher.
Q: Is DTC C1073 set?

YES : Replace the hydraulic unit (incorporates in ASC-ECU).(Refer to HYDRAULIC UNIT .) Then go to Step 11.

NO : Intermittent malfunction. (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION .)
STEP 11. Check whether the DTC is reset.
1. Erase the diagnostic trouble code.
2. Drive the vehicle at 12mph (20 km/h) or more.
  NOTE: The ABS warning light does not turn OFF in some cases unless the vehicle runs at 12mph (20 km/h) or higher.
Q: Is DTC C1073 set?

YES : Return to Step 1.

NO : This diagnosis is complete.