C1620

Code No. C1620 AYC control abnormality

CAUTION
If there is any problem in the CAN bus lines, an incorrect diagnostic trouble code may be set. Prior to this diagnosis, diagnose the CAN bus lines.

OPERATION
^ The power from AWC-ECU is supplied to and energizes the hydraulic unit AYC proportioning valve and direction valve (RH/LH) solenoid.

FUNCTION
^ The AWC-ECU controls the specified current of the coil for the hydraulic unit AYC proportioning valve solenoid, and activation command of the coil for the AYC direction valve (RH/LH) solenoid.
^ The hydraulic unit AYC proportioning valve and direction valve (RH/LH) solenoid control the hydraulic pressure to the AYC differential right/left clutch.

TROUBLE JUDGMENT

Range of check
^ The forced activation of actuator is not underway.
^ The output to the AYC proportioning valve solenoid is 0.05 A or more.

JUDGMENT CRITERIA
^ Due to the AYC differential clutch protection, DTC No. C161F is set.
^ The AYC proportioning valve solenoid is energized longer than the specified duration.

Fail-safe, backup function
^ The AWC-ECU suspends the AYC control and illuminates the multi-information display. Then DTC No. C1620 is set.

PROBABLE CAUSES
^ The driving and road conditions are severe.
^ Malfunction inside the AWC-ECU

DIAGNOSTIC PROCEDURE

STEP 1. CAN bus diagnostics using the scan tool
Using the scan tool, diagnose the CAN bus lines.
Q: Is the check result normal?
YES: Go to Step 3.
NO: Repair the CAN bus line. After repairing the CAN bus line, go to Step 2.

STEP 2. DTC recheck after repairing the CAN bus line
1) Erase the DTC.
2) Turn the ignition switch from the LOCK (OFF) position to the ON position.
3) Check if the DTC is set.
Q: Is DTC No. C1620 set?
YES: Go to Step 3.
NO: This diagnosis is complete.

STEP 3. Check whether the DTC is reset.
1) Erase the DTC.
2) Turn the ignition switch from the LOCK (OFF) position to the ON position.
3) Check if the DTC is set.
Q: Is DTC No. C1620 set?
YES: Replace the AWC-ECU, and check that another DTC is not set. Then go to Step 4.
NO: This diagnosis is complete. Under the driving and road conditions where the AYC control is operated long time (e.g.: long time cornering), the clutch protection is operated.

STEP 4. Check whether the DTC is reset.
1) Erase the DTC.
2) Turn the ignition switch from the LOCK (OFF) position to the ON position.
Q: Is DTC No. C1620 set?
YES: Diagnose again from Step 1.
NO: This diagnosis is complete.