Mitsubishi Eclipse. Manual - part 685

AUTO-CRUISE CONTROL

TSB Revision

ENGINE AND EMISSION CONTROL

17-21

DTC 12: Vehicle Speed Signal System <A/T>

.

AC103147

Vehicle Speed Signal System Circuit

AB

AC001451

CONNECTOR: C-20

AB

AC101201AB

CONNECTOR: C-28

AC001657

CONNECTOR: C-57 <2.4L ENGINE> OR 
C-59 <3.0L ENGINE>

AK

PCM

AC101196AC

CONNECTOR: C-77

AUTO-CRUISE CONTROL

TSB Revision

ENGINE AND EMISSION CONTROL

17-22

CIRCUIT OPERATION
This circuit checks the vehicle speed signal. When 
the vehicle moves forward and reverses, the sensor 
turns ON and OFF repeatedly.

.

DTC SET CONDITIONS
The vehicle speed signals from the PCM are not 
input to the auto-cruise control-ECU when the vehi-
cle speed is 40 km/h (25 mph) or more.

.

TROUBLESHOOTING HINTS
The most likely causes for this code to be set are:

• Malfunction of the output shaft speed sensor.

• Damaged harness or connector.

• Malfunction of the PCM.

• Malfunction of the auto-cruise control-ECU.

DIAGNOSIS

Required Special Tool:

• MB991223: Harness Set

STEP 1. Check the speedometer.
Q: Does the speedometer work normally?

YES : Go to Step 2.
NO :  Check the speedometer circuit and repair or replace 

as required. (Refer to GROUP 54A, Combination 
Meter Assembly and Vehicle Speed Sensor 

P.54A-45

.)

 STEP 2. Check joint connector (1) C-77.
Q: Is the connector damaged?

YES : Repair or replace connector. Refer to GROUP 00E, 

Harness Connector Inspection 

P.00E-2

. Then check 

that diagnostic trouble code 12 is not output.

NO :  Go to Step 3.

AC101196AC

CONNECTOR: C-77

AUTO-CRUISE CONTROL

TSB Revision

ENGINE AND EMISSION CONTROL

17-23

STEP 3. Check the harness wire between auto-cruise 
control-ECU connector C-20 (terminal number 10) and joint 
connector (1) C-77 (terminal number 19).
Q: Is any harness wire between auto-cruise control-ECU 

connector C-20 (terminal number 10) and joint 
connector (1) C-77 (terminal number 19) damaged?
YES : Repair the harness wire and then check that 

diagnostic trouble code 12 is not output.

NO :  Check that diagnostic trouble code 12 is not output. If 

diagnostic trouble code 12 is output, replace the 
auto-cruise control-ECU (Refer to 

P.17-92

.). Then 

check that diagnostic trouble code 12 is not output.

AC001451

CONNECTOR: C-20

AB

AC101196AC

CONNECTOR: C-77

AUTO-CRUISE CONTROL

TSB Revision

ENGINE AND EMISSION CONTROL

17-24

DTC 14 : Stoplight Switch System

AC106577AB

Stoplight Switch System Circuit

AC001449

CONNECTOR: A-01

RESERVE
TANK

AB

AC001451

CONNECTOR: C-20

AB