SUBARU LEGACY 1997 Service Repair Manual

3. Electrical Components Location
B6M0273A
1Actuator

2Vacuum pump and valve

3Inhibitor switch (AT)

4Cruise control main switch
5Cruise control command switch

6Cruise control module

7Stop and brake switch

8Clutch switch (MT)
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6-2BODY ELECTRICAL SYSTEM
3. Electrical Components Location

4. Schematic
B6M0274
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4. Schematic

5. Control Module I/O Signal
G6M0015
ContentTerminal
No.Measuring conditions and I/O signals (ignition switch ON and engine idling)
Main power supply 2
Battery voltage is present when main power is turned ON.

“0”volt is present when main power is turned OFF.
Inhibitor switch (AT) (U.S.A.)
N position switch (AT) (CANADA)4
“0”volt is present when selector lever is set to P or N position (CANADA: N position only).

Battery voltage is present when selector lever is other than P or N position (CANADA: N
position only).
Air valve 5
“0”volt is present when vehicle is stopped.

ON-and-OFF (“0”-and-battery voltage) operation is alternately repeated while cruise control
is operating.
GND 6—
Vacuum pump motor 7
“0”volt is present when vehicle is stopped.

ON-and-OFF (“0”-and-battery voltage) operation is alternately repeated while cruise control
is operating.
Data link connector 8—
RESUME/ACCEL switch 9
Battery voltage is present when switch is turned ON.

“0”volt is present when switch is turned OFF.
SET/COAST switch 10
Battery voltage is present when switch is turned ON.

“0”volt is present when switch is turned OFF.
Ignition switch 12
Battery voltage is present when ignition switch is turned ON.

“0”volt is present when ignition switch is turned OFF.
Release valve 13
“0”volt is present when vehicle is stopped.

ON-and-OFF (“0”-and-battery voltage) operation is alternately repeated while cruise control
is operating.
Power supply to vacuum pump
motor, air valve, release valve14
“0”volt is present when vehicle is stopped.

Battery voltage is present while cruise control is operating.
Cruise main switch 15
Battery voltage is present during pressing the main switch, and then approx. 12 V is
present while switch is turned ON.

“0”volt is present when switch is turned OFF.
Brake switch 16Turn the cruise main switch to ON and leave clutch pedal released (MT).
Then check that;

“0”volt is present when brake pedal is depressed.

Battery voltage is present when brake pedal is released.
Additionally only in MT vehicle, keep the cruise main switch to ON and leave brake pedal
released.
Then check that;

“0”volt is present when clutch pedal is depressed.

Battery voltage is present when clutch pedal is released.
Data link connector 17—
Data link connector 18—
Vehicle speed sensor 2 19Lift-up the vehicle until all four wheels are raised off ground, and then rotate any wheel manu-
ally.
Approx. 5 and 0 volt pulse signals are alternately input to cruise control module.
Stop light switch 20Turn ignition switch to OFF.
Then check that;

Battery voltage is present when brake pedal is depressed.

“0”volt is present when brake pedal is released.
NOTE:
Voltage at terminals 5, 7, 13 and 14 cannot be checked unless vehicle is driving by cruise control operation.
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5. Control Module I/O Signal

6. Diagnostics Chart for On-board
Diagnosis System
A: BASIC DIAGNOSTICS PROCEDURE
Trouble occurs.
Pre-inspection
Check if cruise control main switch turns ON prop-
erly.
OK
Not OK
Diagnostics Chart for Power Line [T700].>
(Main switch fails when turning to ON.)
Check if cruise speed is properly set while driving at
minimum of 40 km/h (25 MPH).
OK
Not OK
Diagnostics Chart with Trouble Code [T800].> (When cruise control cannot be set.)
Check if cruise control is properly released during
operation.
OK
Not OK
Check if cruise speed is held within set speed ±3
km/h (±2 MPH).
OK
Not OK
Basic inspection of actuator, vacuum pump and
valve (When is not running
at a fixed speed.)
Check if RESUME/ACCEL switch functions properly.
OK
Not OK
Diagnostics Chart with Trouble Code [T800].> (When cruise control cannot be set.)
Check if SET/COAST switch functions properly.
OK
Not OK
Check if CANCEL switch functions properly. (Airbag
equipped model)
OK
Not OK
Check if cruise speed is released when brake pedal
is depressed.
OK
Not OK
Set cruise speed again. Check if cruise speed is
released when clutch pedal is depressed (MT
model) or when select lever is moved to“Neutral.”
OK
Not OK
Cruise control system is in good order.











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6. Diagnostics Chart for On-board Diagnosis System

B: ON-BOARD DIAGNOSIS WITH SELECT
MONITOR
1. GENERAL
The on-board diagnosis function of the cruise control sys-
tem uses an external select monitor.
The on-board diagnosis function operates in two
categories, which are used depending on the type of prob-
lems;

Cruise cancel conditions diagnosis

Real-time diagnosis
Applicable cartridge No.: 498349601

Cruise cancel conditions diagnosis
This category of diagnosis requires actual vehicle driv-
ing in order to determine the cause, (as when cruise
speed is cancelled during driving although cruise cancel
condition is not entered).
Cruise control module memory stores the cancel condi-
tion (Code No.) which occurred during driving. When
there are plural cancel conditions (Code No.), they are
shown in order, for 2 seconds per Code No., on the
select monitor.
CAUTION:

The cruise control memory stores not only the
cruise“cancel”which occurred (although“cancel”
operation is not entered by the driver), but also the
“cancel”condition input by the driver.

The content of memory is cleared when ignition
switch or cruise main switch is turned OFF.

Real-time diagnosis
The real-time diagnosis function is used to determine
whether or not the input of output signal system is in good
order, according to signal emitted from switches, sensors,
etc.
Vehicle cannot be driven at cruise speed because prob-
lems occurs in the cruise control system or its associ-
ated circuits.
Monitor the signal conditions from switches and sen-
sors.
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6-2BODY ELECTRICAL SYSTEM
6. Diagnostics Chart for On-board Diagnosis System

2. CRUISE CANCEL CONDITIONS DIAGNOSIS
1) Connect select monitor.
2) Start the engine and turn cruise control main switch to
ON.
3) Set select monitor in“FB0”mode.
4) Drive vehicle at least 40 km/h (25 MPH) with cruise
speed set.
5) If cruise speed is canceled itself (without doing any
cancel operations), a trouble code will appear on select
monitor display.
CAUTION:

A trouble code will also appear when cruise cancel
is effected by driver. Do not confuse.

Have a co-worker ride in vehicle to assist in diagno-
sis during driving.
NOTE:
Trouble code will be cleared by turning ignition switch or
cruise control main switch to OFF.
3. REAL-TIME DIAGNOSIS
1) Connect select monitor.
2) Turn ignition switch and cruise control main switch to
ON.
3) Set select monitor in“FA 0”mode.
4) Ensure that normal indication is displayed when con-
trols are operated as indicated below:

When SET/COAST switch is pressed.

When RESUME/ACCEL switch is pressed.

When brake pedal is depressed. (Stop and brake switch
turns ON.)

When clutch pedal is depressed. (MT model)

When select lever is set to N position. (AT model)
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6. Diagnostics Chart for On-board Diagnosis System

7. Diagnostics Chart for Power Line
A: BASIC DIAGNOSTICS PROCEDURE
Drive at cruise speed.
Cruise speed can be set.
(Cruise control is available.)Cruise speed cannot be set.
(Cruise control is not available.)
Check cruise control main switch
light and circuit.
Check cruise control main
switch circuit.
OK
Not OK
Repair.
Check cruise control main
switch.
OK
Not OK
Repair.
Faulty cruise control module.



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7. Diagnostics Chart for Power Line

B: CHECK INDICATOR AND CIRCUIT IN
CRUISE CONTROL MAIN SWITCH
DIAGNOSIS:

Bulb failure or open harness of the indicator circuit in the
cruise control main switch.
TROUBLE SYMPTOM:

Cruise control can be set, normally indicator does not
come on. (When main switch is pressed.)
1. Check cruise control main switch.
OK
Not OK
Replace bulb.
2. Check circuit between cruise control module
and cruise control main switch indicator light.
OK
Not OK

Repair or replace wiring harness.

If no output from the cruise control module,
replace the cruise control module.
Failure of the cruise control module.
B6M0275


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7. Diagnostics Chart for Power Line

B6M0180
1. CHECK CRUISE CONTROL MAIN SWITCH.
1) Remove cruise control main switch.
2) Measure resistance between cruise control main switch
terminals.
Terminals / Specified resistance:
No. 1—No. 6 / Approx. 50Ω
B6M0528A
B6M0531A
2. CHECK CIRCUIT BETWEEN CRUISE CONTROL
MODULE AND CRUISE CONTROL MAIN SWITCH
INDICATOR LIGHT.
1) Turn the ignition switch to ON.
2) Turn cruise control main switch to ON.
3) Measure voltage between cruise control main switch
connector and the body.
Connector & terminal / Specified voltage:
(i19) No. 1—Body / 10 V, or more
4) Turn the ignition switch and cruise control main switch
to OFF.
5) Remove the connector from the cruise control main
switch.
6) Measure resistance of ground circuit between the
cruise control main switch connector and body.
Connector & terminal / Specified resistance:
(i19) No. 6—Body / 10Ω, max.
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7. Diagnostics Chart for Power Line

C: CHECK CRUISE CONTROL MAIN SWITCH
DIAGNOSIS:

Faulty cruise control main switch, or open harness.
TROUBLE SYMPTOM:

Cruise control main switch is not turned ON and cruise
control cannot be set.
NOTE:
When the main relay (built-in cruise control module)
operates, the main switch circuit is in normal condition.
The main relay operation can be checked by hearing the
operation sounds.
This operation sounds will be heard when ignition switch
and cruise control main switch is turned to ON.
1. Check fuse and power supply.
OK
Not OK
Melted fuse,repair the shorted part of the circuit.
,replace fuse.
2. Check cruise control main switch.
OK
Not OK
Open harness,repair faulty main switch.,
replace.
3. Check harness connector between cruise
control main switch and cruise control
module.
OK
Not OK
Repair or replace wiring harness.
Failure of the cruise control module.
B6M0275



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7. Diagnostics Chart for Power Line