Subaru Legacy III (2000-2003 year). Service manual — part 1001

CC-24

CRUISE CONTROL SYSTEM (DIAGNOSTICS)

DIAGNOSTICS CHART WITH SYMPTOM

G: CHECK INHIBITOR SWITCH (AT)

TROUBLE SYMPTOM:
Cruise control cannot be set.
WIRING DIAGRAM:

CC-00098

4

12

11

B94

12

7

T3

B14

T7

B12

STARTER

MOTOR

INHIBITOR

SWITCH (AT)

CRUISE

CONTROL

MODULE

B12

1 2 3 4
5 6 7 8
9 10 11 12

T7

1 2 3 4 5 6
7 8 9 10 11 12

B94

1 2 3 4 5 6 7 8 9 10

11 12 13 14 15 16 17 18 19 20

CC-25

CRUISE CONTROL SYSTEM (DIAGNOSTICS)

DIAGNOSTICS CHART WITH SYMPTOM

Step

Value

Yes

No

1

CHECK INHIBITOR SWITCH CIRCUIT.
1) Turn ignition switch OFF.
2) Disconnect inhibitor switch harness con-

nector.

3) Turn ignition switch ON.
4) Turn cruise control main switch ON.
5) Measure voltage between harness connec-

tor terminal and chassis ground.

Connector & terminal

(T7) No. 12 (+) — Chassis ground (

−−−−

):

Does the measured value exceed the spec-
ified value?

10 V

Go to step 2.

Check harness for
open or short
between inhibitor
switch and cruise
control module.

2

CHECK INHIBITOR SWITCH CIRCUIT.
1) Turn cruise control main switch and ignition

switch OFF.

2) Disconnect starter motor harness connec-

tor.

3) Measure resistance between inhibitor

switch harness connector terminal and
chassis ground.

Connector & terminal

(T7) No. 7 — (B14) No. 1:

Is the measured value less than the speci-
fied value?

10

Ω

Go to step 3.

Repair harness.

3

CHECK INHIBITOR SWITCH.
Remove and check inhibitor switch. <Ref. to
CC-11, Inhibitor Switch.>
Is inhibitor switch OK?

Inhibitor switch is OK.

Inhibitor switch cir-
cuit is OK.

Replace inhibitor
switch.

CC-26

CRUISE CONTROL SYSTEM (DIAGNOSTICS)

LIST OF DIAGNOSTIC TROUBLE CODE (DTC)

7. List of Diagnostic Trouble Code (DTC)

A: LIST

DTC

Item

Contents of diagnosis

Reference

21

Inner relay is seized.

Cruise control module inner relay is
seized when main switch is OFF.

<Ref. to CC-27, DTC 21, 24, 25 AND 2A CRUISE
CONTROL MODULE BUILT-IN RELAY, CPU RAM,
Diagnostics Chart with Trouble Code.>

22

Vehicle speed sensor

Vehicle speed signal changes more
than 10 km/h (6 MPH) within 350 ms.

<Ref. to CC-28, DTC 22 VEHICLE SPEED SEN-
SOR, Diagnostics Chart with Trouble Code.>

24

Cruise control module is
abnormal.

Two vehicle speed values stored in
cruise control module memory are
not the same.

<Ref. to CC-27, DTC 21, 24, 25 AND 2A CRUISE
CONTROL MODULE BUILT-IN RELAY, CPU RAM,
Diagnostics Chart with Trouble Code.>

25

Cruise control module is
abnormal.

Two output values stored in cruise
control module memory are not the
same.

<Ref. to CC-27, DTC 21, 24, 25 AND 2A CRUISE
CONTROL MODULE BUILT-IN RELAY, CPU RAM,
Diagnostics Chart with Trouble Code.>

28

Wiring harness opened.

Open wiring harness circuit is
detected via control module relay
when main switch is ON.

<Ref. to CC-31, DTC 28 WIRING HARNESS
OPENED., Diagnostics Chart with Trouble Code.>

35

Motor drive system is
abnormal.

• Motor output circuit is open or
shorted.
• Motor drive circuit is open or
shorted.

<Ref. to CC-32, DTC 35 AND 36 ACTUATOR
MOTOR, Diagnostics Chart with Trouble Code.>

36

Trouble of motor turning
speed

Motor turning speed is low.

<Ref. to CC-32, DTC 35 AND 36 ACTUATOR
MOTOR, Diagnostics Chart with Trouble Code.>

37

Motor clutch drive system
is abnormal.

• Motor clutch output circuit is open
or shorted.
• Motor clutch drive circuit is open or
shorted.

<Ref. to CC-34, DTC 37 ACTUATOR MOTOR
CLUTCH, Diagnostics Chart with Trouble Code.>

38

Motor drive shaft does not
engage properly.

Motor drive gear engagement is not
properly adjusted.

<Ref. to CC-36, DTC 38 MOTOR DRIVE SHAFT
DOES NOT ENGAGE PROPERLY., Diagnostics
Chart with Trouble Code.>

39

Motor is overloaded.

Current flows through motor more
frequently than under normal condi-
tions.

<Ref. to CC-36, DTC 39 MOTOR IS OVER-
LOADED., Diagnostics Chart with Trouble Code.>

2A

Cruise control module is
abnormal.

Cruise control module self-diagnosis
function senses abnormality.

<Ref. to CC-27, DTC 21, 24, 25 AND 2A CRUISE
CONTROL MODULE BUILT-IN RELAY, CPU RAM,
Diagnostics Chart with Trouble Code.>

CC-27

CRUISE CONTROL SYSTEM (DIAGNOSTICS)

DIAGNOSTICS CHART WITH TROUBLE CODE

8. Diagnostics Chart with Trouble Code

A: DTC 21, 24, 25 AND 2A CRUISE CONTROL MODULE BUILT-IN RELAY, CPU

RAM

DIAGNOSIS:
• Poor welding of built-in relay of cruise control module.
• Failure of built-in CPU RAM of cruise control module.
TROUBLE SYMPTOM:
• Cruise control is canceled and memorized cruise speed is also canceled.
• Once cruise control is canceled, cruise control cannot be set until the ignition switch and cruise control
main switch turns OFF, and then turns ON again.

NOTE:
Check input/output signal and vehicle speed signal with select monitor. When signals are in good condition,
failure is in cruise control module. (Check power supply and ground conditions of cruise control module.)