Mitsubishi Eclipse. Manual - part 698

AUTO-CRUISE CONTROL

TSB Revision

ENGINE AND EMISSION CONTROL

17-73

STEP 3.Using scan tool MB991958, check data list.

CAUTION

To prevent damage to scan tool MB991958, always turn the 
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991958.
(1) Using scan tool MB991958.
(2) Connect scan tool MB991958 to the data link connector.
(3) Check the following items in the data list. Refer to 

P.17-84

, 

Data List Reference Table.

• Item 04: Auto-cruise control "CANCEL" switch.

• Item 05: Stoplight switch.

• Item 14: Clutch pedal position switch. <M/T>.

• Item 14: Transmission range switch. <A/T>

(4)  Turn the ignition switch to the "ON" position.
Q: Is the check above meet the specifications?

YES : Check that the malfunction is eliminated. If the 

malfunction is not eliminated, replace the auto-cruise 
control-ECU. (Refer to 

P.17-92

.) Then that the 

malfunction is eliminated.

NO :  Follow the diagnostic trouble code procedures and 

the symptom procedures below. 

• Item 04: Refer to 

Diagnostic Trouble Code Procedures number 15 

P.17-33

. 

• Item 05: Refer to Symptom Procedures 

number 2 

P.17-56

. 

• Item 14: Refer to Symptom 

Procedures number 3 <M/T>

P.17-62

 . 

• Item 14: 

Refer to Symptom Procedures number 4 
<A/T>

P.17-67

 .

INSPECTION PROSEDURE 7:Hunting (Repeated Acceleration and Deceleration) Occurs at the Set 
Vehicle Speed. <M/T>

.

TECHNICAL DESCRIPTION (COMMENT)
The cause is probably the malfunction of the vehicle 
speed sensor or incorrect vacuum in the auto-cruise 
control vacuum pump or actuator.

.

TROUBLESHOOTING HINTS

• Malfunction of the vehicle speed sensor.

• Malfunction of the auto-cruise control vacuum 

pump.

• Malfunction of the actuator.

• Malfunction of the auto-cruise control-ECU.

DIAGNOSIS

Required Special Tool:

• MB991223: Harness Set

AC303127

AB

MB991911

16-PIN

MB991827

MB991824 

AUTO-CRUISE CONTROL

TSB Revision

ENGINE AND EMISSION CONTROL

17-74

STEP 1. Check the vehicle speed sensor.
(1) Remove the vehicle speed sensor and connect a 3 

− 10 kΩ 

resistor as shown in the illustration.

(2) Turn the shaft of the vehicle speed sensor and check that 

there is voltage between terminals 2 

− 3. (one turn = four 

pulses.)

Q: Is the voltage within specifications?

YES : Go to Step 2.
NO :  Replace the vehicle speed sensor. Refer to GROUP 

54A, Combination Meter Assembly and Vehicle 
Speed Sensor 

P.54A-112

. Then check that the 

malfunction is eliminated.

STEP 2. Check the auto-cruise vacuum pump.
(1) Disconnect the vacuum hose from the auto-cruise vacuum 

pump and connect a vacuum gauge to the vacuum pump.

(2) Disconnect the vacuum pump connector.
(3) Check the auto-cruise vacuum pump and valves according 

to the following procedure:

• Connect the positive battery terminal to auto-cruise vac-

uum pump connector terminal 1, and the negative bat-
tery terminal to terminals 2, 3, and 4. Then the vacuum 
gauge should read 27 kPa (8.0 in Hg) or more.

• The vacuum should be maintained when terminal 4 is 

disconnected from the negative battery terminal while 
terminals 1, 2, and 3 remain connected. Then the vac-
uum gauge should read 0 kPa (0 in Hg) when terminal 2 
is disconnected from the negative battery terminal while 
terminals 1, and 3 remain connected.

• The vacuum should be maintained when terminal 4 is 

disconnected from the negative battery terminal while 
terminals 1, 2, and 3 remain connected. Then the vac-
uum gauge should read 0 kPa (0 in Hg) when terminal 3 
is disconnected from the negative battery terminal while 
terminals 1, and 2 remain connected.

Q: Are all of the above values satisfied?

YES : Go to Step 3.
NO :  Replace the auto-cruise vacuum pump (Refer to 

P.17-92

.). Then that the malfunction is eliminated.

AC004598AB

RESISTOR
3 – 10 k

Ω

SHAFT

TURN

ACX01181AB

VACUUM 
GAUGE

CONTROL
VALVE

RELEASE
VALVE

AUTO-CRUISE CONTROL

TSB Revision

ENGINE AND EMISSION CONTROL

17-75

STEP 3. Check the vacuum actuator.
(1) Disconnect the vacuum hose from the vacuum actuator, 

and then connect a hand vacuum pump to the vacuum 
actuator.

(2) Apply a vacuum and check that the throttle lever moves and 

the vacuum is maintained.

Q: Is the vacuum actuator damaged?

YES : Replace the vacuum actuator. For 2.4L engine, refer 

to GROUP 13A, Throttle Body Assembly 

P.13A-946

. 

For 3.0L engine, refer to GROUP 13B, Throttle Body 
Assembly 

P.13B-1117

. Then check that the 

malfunction is eliminated.

NO :  Check that the malfunction is eliminated. If the 

malfunction is not eliminated, replace the auto-cruise 
control-ECU. (Refer to 

P.17-92

.) Then check that the 

malfunction is eliminated.

INSPECTION PROSEDURE 8: Hunting (Repeated Acceleration and Deceleration) Occurs at the Set 
Vehicle Speed. <A/T>

.

TECHNICAL DESCRIPTION (COMMENT)
The cause is probably the malfunction of the output 
shaft speed sensor or PCM or incorrect vacuum in 
the auto-cruise control vacuum pump or actuator.

.

TROUBLESHOOTING HINTS

• Malfunction of the output shaft speed sensor.

• Malfunction of the PCM.

• Malfunction of the auto-cruise control vacuum 

pump.

• Malfunction of the actuator.

• Malfunction of the auto-cruise control-ECU.

DIAGNOSIS

Required Special Tool:

• MB991958: Scan Tool (MUT-III sub assembly)

• MB991824: Vehicle Communication Interface

• MB991827: MUT-III USB Cable

• MB991911: MUT-III Main Harness B

• MB991223: Harness Set

AC001493

THROTTLE BODY

VACUUM ACTUATOR

AB

AUTO-CRUISE CONTROL

TSB Revision

ENGINE AND EMISSION CONTROL

17-76

STEP 1. Check the vehicle speed signal.

CAUTION

To prevent damage to scan tool MB991958, always turn the 
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991958.
(1) Using scan tool MB991958.
(2) Connect scan tool MB991958 to the data link connector.
(3)  Turn the ignition switch to the "ON" position.
(4) Read the MFI-DTC.
(5) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the MFI-DTC P0720 is output?

YES : For 2.4L engine, refer to GROUP 13A, Diagnosis 

− 

Diagnostic Trouble Code Chart 

P.13A-24

. For 3.0L 

engine, refer to GROUP 13B, Diagnosis 

− Diagnostic 

Trouble Code Chart 

P.13B-23

.

NO :  Go to Step 2.

STEP 2. Check the auto-cruise vacuum pump.
(1) Disconnect the vacuum hose from the auto-cruise vacuum 

pump and connect a vacuum gauge to the vacuum pump.

(2) Disconnect the vacuum pump connector.
(3) Check the auto-cruise vacuum pump and valves according 

to the following procedure:

• Connect the positive battery terminal to auto-cruise vac-

uum pump connector terminal 1, and the negative bat-
tery terminal to terminals 2, 3, and 4. Then the vacuum 
gauge should read 27 kPa (8.0 in Hg) or more.

• The vacuum should be maintained when terminal 4 is 

disconnected from the negative battery terminal while 
terminals 1, 2, and 3 remain connected. Then the vac-
uum gauge should read 0 kPa (0 in Hg) when terminal 2 
is disconnected from the negative battery terminal while 
terminals 1, and 3 remain connected.

• The vacuum should be maintained when terminal 4 is 

disconnected from the negative battery terminal while 
terminals 1, 2, and 3 remain connected. Then the vac-
uum gauge should read 0 kPa (0 in Hg) when terminal 3 
is disconnected from the negative battery terminal while 
terminals 1, and 2 remain connected.

Q: Are all of the above values satisfied?

YES : Go to Step 3.
NO :  Replace the auto-cruise vacuum pump (Refer to 

P.17-92

.). Then that the malfunction is eliminated.

AC303127

AB

MB991911

16-PIN

MB991827

MB991824 

ACX01181AB

VACUUM 
GAUGE

CONTROL
VALVE

RELEASE
VALVE