C145A
DTC C145A: Wiring harness and coupling coil short circuit failure
CAUTION: If there is any problem in the CAN bus lines, an incorrect DTC may be set. Prior to this diagnosis, always diagnose the CAN bus lines.
OPERATION
If the current flowing the electronic control coupling solenoid coil is larger than the command value from AWD-ECU, the system is deactivated.
DTC SET CONDITIONS
If the following conditions are met when the system is activated, AWD-ECU switches the control from AWD to FWD, flashes the AWD/LOCK indicators alternately, and sets the DTC No. C145A.
^ Sets the specified current command value to the electronic control coupling solenoid
^ Drive current value of the electronic control coupling solenoid: Deviated over from the normal current range
TROUBLESHOOTING HINTS
Current trouble
^ Short circuit inside the electronic control coupling solenoid
^ Wiring harness or connector failure (short circuit between the electronic control coupling solenoid terminals)
^ Damaged wiring harness and connectors
- Short to earth between AWD-ECU and the electronic control coupling solenoid
^ AWD-ECU internal error
Past trouble
^ Intermittent wiring harness or connector failure
NOTE: For diagnosis procedures, refer to "How to treat past trouble".
^ Intermittent electronic control coupling failure (solenoid failure)
DIAGNOSIS
^ MB991958: Scan Tool (M.U.T.-III Sub Assembly)
^ MB991824: Vehicle Communication Interface
^ MB991827: M.U.T.-III USB Cable
^ MB991910: M.U.T.-III Main Harness A
STEP 1. Scan tool MB991958 CAN bus diagnostics
Use scan tool MB991958 to diagnose the CAN bus lines.
Q:Is the check result normal?
YES: Go to Step 3.
NO: Repair the CAN bus line. On completion, go to Step 2.
STEP 2. Check whether the DTC is reset after repairing the CAN bus line.
(1) Erase the DTC.
(2) Turn the ignition switch from the LOCK (OFF) position to the ON position and hold there for 2 seconds.
(3) Fully depress the accelerator pedal, and maintain its position for 2 seconds.
NOTE: The coupling coil electronic control is also based on the accelerator pedal opening degree, thus the signal is sent to the ECU.
(4) Check if the DTC is set.
Q:Is the DTC No. C145A set?
YES: Go to Step 3.
NO: This diagnosis is complete.
STEP 3. Scan tool MB991958 data list
Check the following service data.
^ Item 04: Coupling current command value
^ Item 05: Coupling current monitor value
Q:Is the check result normal?
YES: Replace AWD-ECU.
NO: Go to Step 4.
STEP 4. Check the following connector:
Check the connectors below for improper engagement, terminal damage or terminal drawn in the connector case.
^ C-128 AWD-ECU connector
^ D-113 intermediate connector
^ D-119 electronic control coupling solenoid connector
^ C-31 intermediate connector
Q:Are the connectors and terminals in good condition?
YES: Go to Step 5.
NO: Repair the connector(s) or terminal(s). Then go to Step 10.
STEP 5. Wiring harness check
Check the wiring harness between the C-128 AWD-ECU connector and the D-113 intermediate connector, and the wiring harness between the D-113 intermediate connector and the D-119 electronic control coupling solenoid side connector for damage or other problem.
Q:Is the wiring harness in good condition?
YES: Go to Step 6.
NO: Repair damage or other problem in the wiring harness. Then go to Step 10.
STEP 6. Resistance measurement between electronic control coupling solenoid connector (coupling side) terminals
Disconnect the D-119 connector, and measure the resistance value between the connector terminals on the electronic control coupling side.
Standard value: 2.2 - 4.0 Ohms
Q:Is the measured resistance value within the standard value range?
YES: Go to Step 7.
NO: Replace the electronic control coupling. Then go to Step 10.
STEP 7. Voltage measurement at the AWD-ECU connector
(1) Disconnect the C-128 AWD-ECU connector.
(2) Measure the voltage between the C-128 wiring harness side connector terminals No. 3/4 and No. 10.
OK: Battery voltage
Q:Is the check result normal?
YES: Go to Step 9.
NO: Go to Step 8.
STEP 8. Wiring harness check
NOTE: Prior to the wiring harness inspection, check the C-315 ETACS-ECU connector, and repair if necessary.
^ Wiring harness between the C-128 AWD-ECU connector (terminal No. 3) and the C-309 ETACS-ECU connector (terminal No. 1)
Check the wiring harness above for damage or other problem.
Q:Is the wiring harness in good condition?
YES: Go to Step 9.
NO: Repair the wiring harness. Then go to Step 10.
STEP 9. Check whether the DTC is reset.
(1) Erase the DTC.
(2) Turn the ignition switch from the LOCK (OFF) position to the ON position and hold there for 2 seconds.
(3) Fully depress the accelerator pedal, and maintain its position for 2 seconds.
NOTE: The coupling coil electronic control is also based on the accelerator pedal opening degree, thus the signal is sent to the ECU.
(4) Check if the DTC is set.
Q:Is the DTC No. C145A set?
YES: Replace AWD-ECU. Then go to Step 10.
NO: The trouble can be an intermittent malfunction.
STEP 10. Check whether the DTC is reset.
(1) Erase the DTC.
(2) Turn the ignition switch from the LOCK (OFF) position to the ON position and hold there for 2 seconds.
(3) Fully depress the accelerator pedal, and maintain its position for 2 seconds.
NOTE: The coupling coil electronic control is also based on the accelerator pedal opening degree, thus the signal is sent to the ECU.
(4) Check if the DTC is set.
Q:Is the DTC No. C145A set?
YES: Diagnose again from Step 1.
NO: This diagnosis is complete.