Mitsubishi Galant. Manual — part 372

AUTO-CRUISE CONTROL

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ENGINE AND EMISSION CONTROL

17-58

DIAGNOSIS

Required Special Tools:

•

MB991502: Scan Tool (MUT-II)

•

MB991223: Harness Set

STEP 1. Can the auto-cruise control-ECU communicate
with scan tool MB991502?

CAUTION

To prevent damage to scan tool MB991502, always turn the
ignition switch to "LOCK"(OFF) position before
connecting or disconnecting scan tool MB991502.
(1) Using scan tool MB991502.
(2) Connect scan tool MB991502 to the data link connector.
(3) Turn the ignition switch to "ON" position.

Q: Can the auto-cruise control-ECU communicate with the

scan tool?
YES : Go to Step 2.
NO : Inspect each trouble symptom.

(Refer to Inspection Procedure number 1

P.17-39

.)

STEP 2. Is any diagnostic trouble code output?

Q: Is any diagnostic trouble code output?

YES : Diagnostic trouble code number 11, 12, 14, 15, 16 or

17 is output, refer to the following.
(Code number 11

P.17-11

.)

(Code number 12

P.17-16

.)

(Code number 14

P.17-19

.)

(Code number 15

P.17-28

.)

(Code number 16

P.17-33

.)

(Code number 17

P.17-34

.)

Then check that the malfunction is eliminated.

NO : Go to Step 3.

AC004569

MB991502

16 PIN

AB

AUTO-CRUISE CONTROL

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ENGINE AND EMISSION CONTROL

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STEP 3.Using scan tool MB991502, check data list.

CAUTION

To prevent damage to scan tool MB991502, always turn the
ignition switch to "LOCK"(OFF) position before
connecting or disconnecting scan tool MB991502.
(1) Using scan tool MB991502.
(2) Connect scan tool MB991502 to the data link connector.
(3) Check the following items in the data list.

Refer to

P.17-67

, Data List Reference Table.

•

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

•

Item 05: Stoplight switch.

•

Item 14: Park/neutral position switch.

(4) Turn the ignition switch to "ON" position.

Q: Is the check above meet the specifications?

YES : Check that the malfunction is eliminated.

If the malfunction is eliminated, replace the auto-
cruise control-ECU. (Refer to

P.17-74

.)

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.17-28

.

•

Item 05: Refer to Symptom Procedures number 2

P.17-46

.

•

Item 14: Refer to Symptom Procedures number 3

P.17-53

.

INSPECTION PROCEDURE 6:Hunting (Repeated Acceleration and Deceleration) Occurs at the Set
Vehicle Speed.

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

AC004569

MB991502

16 PIN

AB

AUTO-CRUISE CONTROL

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ENGINE AND EMISSION CONTROL

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

−

10 k

Ω

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-65

.

Then check that the malfunction is eliminated.

AC004598AB

RESISTOR
3 – 10 k

Ω

SHAFT

TURN

AUTO-CRUISE CONTROL

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ENGINE AND EMISSION CONTROL

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STEP2. 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
vacuum pump connector terminal 1, and the negative
battery 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 vacuum 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 vacuum 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.17-74

.)

Then that the malfunction is eliminated.

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-452

.

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

P.13B-529

.

Then check that the malfunction is eliminated.

NO : Check that the malfunction is eliminated.

If the malfunction is eliminated, replace the auto-
cruise control-ECU. (Refer to

P.17-74

.)

Then check that the malfunction is eliminated.

ACX01181AB

VACUUM
GAUGE

CONTROL
VALVE

RELEASE
VALVE

AC001493

THROTTLE BODY

VACUUM ACTUATOR

AB