AUTOMATIC TRANSMISSION (DIAGNOSTICS)(4AT) > Diagnostic Procedure with Diagnostic Trouble Code (DTC)

DTC P0724 BRAKE SWITCH CIRCUIT HIGH

DTC DETECTING CONDITION:

Brake switch malfunction, open input signal circuit

TROUBLE SYMPTOM:

• Gear is not shifted down when driving a down hill.

• Neutral control does not operate.

WIRING DIAGRAM:

STEPCHECKYESNO

1.CHECK DTC.

Is DTC of CAN communication displayed?

Perform diagnosis according to the DTC.

2.CHECK BODY INTEGRATED UNIT.

1) Turn the ignition switch to OFF.

2) Connect the Subaru Select Monitor to the data link connector.

3) Turn the ignition switch to ON.

4) Run the Subaru Select Monitor.

5) Read the data of “Stop Light Switch” using Subaru Select Monitor.

Is “OFF” displayed?

3.CHECK TCM.

Read the data of “Stop Light Switch” using Subaru Select Monitor.

Is “OFF” displayed?

Check for poor contact in the connector or harness, and repair the fault location.

Replace the TCM.

4.CHECK BODY INTEGRATED UNIT INPUT SIGNAL.

1) Disconnect the harness connector of body integrated unit.

2) Measure the voltage of harness between body integrated unit and stop light switch.

Connector & terminal

(B280) No. 2 (+) — Chassis ground (−):

Is the voltage 10 V or more?

5.CHECK STOP LIGHT SWITCH.

1) Turn the ignition switch to OFF.

2) Disconnect the connector from stop light switch.

3) Measure the resistance of harness between stop light switch connectors.

Connector & terminal

Without push button start

With cruise control

(B65) No. 2 — No. 3:

Without cruise control

(B64) No. 1 — No. 2:

With push button start

(B65) No. 2 — No. 3:

Is the resistance 1 MΩ or more?

Replace the stop light switch.

6.CHECK HARNESS CONNECTOR BETWEEN BODY INTEGRATED UNIT AND STOP LIGHT SWITCH.

1) Turn the ignition switch to ON.

2) Measure the voltage of harness between the body integrated unit and chassis ground.

Connector & terminal

(B280) No. 2 (+) — Chassis ground (−):

Is the voltage less than 1 V?

Repair the short circuit of harness between TCM and stop light switch.

7.CHECK FOR POOR CONTACT.

Is there poor contact in input signal of brake switch?

Repair the poor contact.

Check the body integrated unit.