Mitsubishi Evolution X. Manual - part 887

REAR AXLE DIAGNOSIS <AYC>

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REAR AXLE

27-9

INSPECTION PROCEDURE FOR DIAGNOSIS CODE

Code No. C1619 AYC current value abnormality

S-AWC-ECU

DIRECTION
VALVE (LH)

DIRECTION
VALVE (RH)

PROPORTIONING
VALVE

FOR AYC
CONTROL

AC708205

Proportioning valve system/direction valve system circuit

Wire colour code
B: Black  LG: Light green  G: Green  L: Blue  W: White  Y: Yellow  SB: Sky blue  BR: Brown  O: Orange  GR: Gray
R: Red  P: Pink  V: Violet  PU: Purple  SI: Silver

AB

C-46

D-11

F-11

F-12

F-10

F-17

F-11

AC708196

AC708214

Connector: C-46

AB

AC706034 AB

Connector: D-11

AC706035 AB

F-11

Connector: F-11, F-17
Body earth: No.9

F-17 (B)

No.9

REAR AXLE DIAGNOSIS <AYC>

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REAR AXLE

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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 solenoid.

.

FUNCTION

• The AWC-ECU controls the specified current of 

the coil for the hydraulic unit AYC proportioning 
valve solenoid.

• The hydraulic unit AYC proportioning valve sole-

noid controls the hydraulic pressure to the AYC 
differential right/left clutch.

.

TROUBLE JUDGMENT

Range of check

• The output to the AYC proportioning valve sole-

noid is 0.05 A or more.

• The DTC related to the power supply circuit is not 

set.

JUDGMENT CRITERIA

• The current monitor value of the AYC proportion-

ing valve solenoid is abnormal.

Fail-safe, backup function

• AWC-ECU suspends the AYC control and illumi-

nates the multi-information display. Then DTC 
No. C1619 is set.

.

PROBABLE CAUSES

• Malfunction inside the AYC proportioning valve 

solenoid

• Damaged harness wires and connectors

• Open circuit, short to ground, and connector 

continuity failure between the AWC-ECU and 
the AYC proportioning valve solenoid

• Open circuit and connector continuity failure 

between the AYC proportioning valve sole-
noid and the body ground

• Malfunction inside the AWC-ECU

DIAGNOSTIC PROCEDURE

STEP 1. Scan tool CAN bus diagnostics
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 (Refer to GROUP 54C 

− 

Troubleshooting 

P.54C-14

). After repairing the CAN 

bus line, go to Step 2.

REAR AXLE DIAGNOSIS <AYC>

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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, and then wait for 4 seconds.

(3) Check if the DTC is set.
Q: Is DTC No. C1619 set?

YES : Go to Step 3.
NO :  This diagnosis is complete.

STEP 3. Connector check:
Check the connectors below for improper engagement, termi-
nal damage or terminal drawn in the connector case.

• C-46 AWC-ECU connector

• F-17 AYC proportioning valve connector

• D-11 intermediate connector, F-11 intermediate connector

• No. 9 body ground

Q: Are the connectors and terminals in good condition?

YES : Go to Step 4.
NO :  Repair the faulty connector(s) or terminal(s). Then go 

to Step 8.

STEP 4. Harness check
(1) Check the wiring harness among C-46 AWC-ECU 

connector (terminal No. 2), D-11 intermediate connector 
(terminal No. 1), F-11 intermediate connector (terminal No. 
4), and F-17 AYC proportioning valve connector (terminal 
No. 3) for any problems.

(2) Check the wiring harness among F-17 AYC proportioning 

valve connector (terminal No. 2), F-11 intermediate 
connector (terminal No. 3), and No. 9 body ground for any 
problems.

Q: Is the harness in good condition?

YES : Go to Step 5.
NO :  Repair the problem in the wiring harness. Then go to 

Step 8.

STEP 5. Resistance measurement between AYC 
proportioning valve solenoid connector (equipment side) 
terminals

AC705248AB

Hydraulic unit
assembly

Proportioning
valve for AYC control

F-17(B)Harness connector:
valve side

Disconnect the F-17 AYC proportioning valve connector and 
measure the resistance between connector terminals on the 
equipment side.

Standard value: 3.7 

± 0.3 Ω

Q: Is the measured resistance value within the standard 

value range?
YES : Go to Step 6.
NO :  Replace the hydraulic unit. (Refer to 

P.27-58

.) Then 

go to Step 8.

REAR AXLE DIAGNOSIS <AYC>

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STEP 6. Scan tool service data
Check the following service data. (Refer to 

P.27-22

.)

• Item 93: Specified current for AYC proportioning valve

Q: Is the check result normal?

YES : Go to Step 7.
NO :  Replace the AWC-ECU (Refer to 

P.22A-132

). Then, 

go to Step 8.

STEP 7. 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 then wait for 4 seconds.

(3) Check if the DTC is set.
Q: Is DTC No. C1619 set?

YES : Replace the AWC-ECU (Refer to 

P.22A-132

). Then 

go to Step 8.

NO :  An intermittent malfunction is suspected. (Refer to 

GROUP 00 

− How to Cope with Intermittent 

Malfunction 

P.00-15

.)

STEP 8. 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 then wait for 4 seconds.

(3) Check if the DTC is set.
Q: Is DTC No. C1619 set?

YES : Diagnose again from Step 1.
NO :  This diagnosis is complete.