Mitsubishi 380. Manual - part 344

AUTO-CRUISE CONTROL

ENGINE AND EMISSION CONTROL

17-44

STEP 13. Using Diagnostic Tool MB991958, check data list 
item 74: Stoplamp Switch.

CAUTION

To prevent damage to Diagnostic Tool MB991958, always 
turn the ignition switch to the "LOCK" (OFF) position 
before connecting or disconnecting Diagnostic Tool 
MB991958. 
(1) Connect Diagnostic Tool MB991958 to the data link 

connector. (Refer to 

P.17-11

).

(2) Turn the ignition switch to the "ON" position.
(3) Set Diagnostic Tool MB991958 to data reading mode for 

auto-cruise control system. (Refer to 

P.17-11

).

• Item 74, Stoplamp Switch.

• When the brake pedal is depressed, the display on 

Diagnostic Tool MB991958 should be "ON".

• When the brake pedal is released, the display on 

Diagnostic Tool MB991958 should be "OFF".

(4) Turn the ignition switch to the "LOCK" (OFF) position.
(5) Disconnect Diagnostic Tool MB991958.

Q: Is the switch operating properly?

YES : Go to Step 21.
NO :  Replace the Engine ECU. [Refer to GROUP 13A,  

Engine ECU 

13A-675

] . Then go to Step 22.

STEP 14. Using Diagnostic Tool MB991958, check data list 
item 89: Normally closed Brake Switch.

CAUTION

To prevent damage to Diagnostic Tool MB991958, always 
turn the ignition switch to the "LOCK" (OFF) position 
before connecting or disconnecting Diagnostic Tool 
MB991958. 
(1) Connect Diagnostic Tool MB991958 to the data link 

connector. (Refer to 

P.17-11

).

(2) Turn the ignition switch to the "ON" position.
(3) Set Diagnostic Tool MB991958 to data reading mode for 

auto-cruise control system. (Refer to 

P.17-11

).

• Item 89, Normally closed Brake Switch.

• When the brake pedal is depressed, the display on 

Diagnostic Tool MB991958 should be "ON".

• When the brake pedal is released, the display on 

Diagnostic Tool MB991958 should be "OFF".

(4) Turn the ignition switch to the "LOCK" (OFF) position.
(5) Disconnect Diagnostic Tool MB991958.

Q: Is the switch operating properly?

YES : Go to Step 21.
NO :  Go to Step 15.

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AUTO-CRUISE CONTROL

ENGINE AND EMISSION CONTROL

17-45

STEP 15. Measure the terminal voltage at Engine ECU 
connector B-21.
(1) Disconnect all the connectors from the Engine ECU.
(2) Connect special tool MB992044 between the Engine ECU 

and the body-side harness connector.

(3) Turn the ignition switch to the "ON" position.
(4) Measure the terminal voltage between special tool 94-pin 

connector  terminal 21 (Engine ECU connector B-21 
terminal 21) and ground.

• When the brake pedal is depressed, the voltage should 

measure battery positive voltage (approximately 12 
volts).

• When the brake pedal is released, the voltage should 

measure 1 volt or less.

(5) Turn the ignition switch to the "LOCK" (OFF) position.
(6) Disconnect special tool MB992044 between the Engine 

ECU and the body-side harness connector.

(7) Reconnect all the connectors to the Engine ECU.

Q: Is the measured voltage battery positive voltage 

(approximately 12 volts) when the brake pedal is 
depressed and 1 volt or less when the brake pedal is 
released?
YES : Go to Step 20.
NO :  Go to Step 16.

STEP 16. Check the stoplamp switch.
(1) Remove the stoplamp switch. (Refer to GROUP 35A, Brake 

Pedal 

P.35A-24

).

(2) Connect an ohmmeter to the stoplamp switch between 

terminals 3 and 4.

(3) Check for continuity between the terminals when the 

plunger of the stoplamp switch is pushed in and when it is 
released.

(4) The stoplamp switch is operating properly if the circuit is 

open between terminals 3 and 4 when the plunger is 
pushed in, and if resistance value is less than 2 ohms 
between terminals 3 and 4 when the plunger is released.

Q: Is the stoplamp switch operating properly?

YES : Install the stoplamp switch. (Refer to GROUP 35A, 

Brake Pedal 

P.35A-24

). Then go to Step 17.

NO :  Replace the stoplamp switch. (Refer to GROUP 35A, 

Brake Pedal 

P.35A-24

). Then go to Step 22.

16DB400A

COVER

ENGINE

CONTROL

UNIT

AIR

CLEANER

1

2

3

4

ACX01917AJ

C-30 STOPLIGHT SWITCH
CONNECTOR

AC205057    

CONTINUITY

NO

CONTINUITY

4.5 mm (0.18 in)

AC

AUTO-CRUISE CONTROL

ENGINE AND EMISSION CONTROL

17-46

STEP 17. Check Engine ECU connector B-21 and stoplamp 
switch connector C-30 for loose, corroded or damaged 
terminals, or terminals pushed back in the connector.
Q: Are the connectors and terminals in good condition?

YES : Go to Step 18.
NO :  Repair or replace the damaged components. (Refer to 

GROUP 00E, Harness Connector Inspection 

P.00E-2

). Then go to Step 22.

16DB400A

COVER

ENGINE

CONTROL

UNIT

AIR

CLEANER

17DB045A

CONNECTOR: C-30

C-30

C-30 HARNESS
CONNECTOR:
COMPONENT SIDE

AUTO-CRUISE CONTROL

ENGINE AND EMISSION CONTROL

17-47

STEP 18. Check the harness wire between Engine ECU 
connector B-21 terminal 21 and stoplamp switch 
connector C-30 terminal 3 for damage.
Q: Is the harness wire in good condition?

YES : Go to Step 19.
NO :  Repair the damaged harness wire if possible, or as 

recommended, replace complete harness. Then go to 
Step 22.

STEP 19. Check the harness wire between stoplamp 
switch connector C-30 terminal 4 and ground for damage.
Q: Is the harness wire in good condition?

YES : Go to Step 20.
NO :  Repair the damaged harness wire if possible, or as 

recommended, replace complete harness. Then go to 
Step 22.

16DB400A

COVER

ENGINE

CONTROL

UNIT

AIR

CLEANER

17DB045A

CONNECTOR: C-30

C-30

C-30 HARNESS
CONNECTOR:
COMPONENT SIDE

16DB401A

ENGINE 

   ECU

GROUND
TERMINAL

RELAY BOX