DTC P0703: Malfunction of Stoplight Switch

DIAGNOSTIC FUNCTION

TCM detects malfunction using the stoplight switch signal sent from the ETACS-ECU.

DESCRIPTIONS OF MONITOR METHODS

Drive the vehicle at 30 km/h (19 mph) or more for 10 seconds, and then turn the ignition switch to the "LOCK" (OFF) position. In this sequential operation, no variation has been found in the stoplight switch input signal in two consecutive times.

MONITOR EXECUTION

Continuous

MONITOR EXECUTION CONDITIONS (OTHER MONITOR AND SENSOR)

Other Monitor (There is no temporary DTC stored in memory for the item monitored below)

Not applicable

Sensor (The sensor below is determined to be normal)

Not applicable

LOGIC FLOW CHARTS (Monitor Sequence)

DTC SET CONDITIONS

Check Conditions

Vehicle speed: 30 km/h (19 mph) or more.
Voltage of battery: 9 volts or more.
Voltage of battery: 16 volts or less.

Judgment Criteria

The change of stoplight switch signal during driving cycle: no occurrence (10 seconds × 2 times).

OBD-II DRIVE CYCLE PATTERN

Drive the vehicle for 10 seconds or more at 30 km/h (19 mph) or higher (2 drive cycle)

PROBABLE CAUSES

Malfunction of the CAN bus
Malfunction of the stoplight switch
Damaged wiring harness and connectors
Malfunction of TCM
Malfunction of ETACS-ECU

DIAGNOSTIC PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics

Use M.U.T.-III to perform the CAN bus diagnosis.

Q. Is the check result normal?

	Go to Step 2.

	Repair the CAN bus lines (Refer to GROUP 54C, Troubleshooting - Diagnosis Code Chart ).

STEP 2. M.U.T.-III data list

Item 50: Brake switch

OK: The service data changes in response to the brake operation.

Q. Is the check result normal?

	Intermittent malfunction

	Go to Step 3.

STEP 3. Check the following connector:

C-304 ETACS-ECU connector
C-312 ETACS-ECU connector
C-32 Stoplight switch connector

Check the contact status of the terminals.

Q. Is the check result normal?

	Go to Step 4.

	Repair the defective connector.

STEP 4. Stoplight Switch Check

Refer to GROUP 35A, Brake Pedal

Q. Is the check result normal?

	Go to Step 5.

	Replace the stoplight switch.

STEP 5. Check for open circuit in the wiring harness between the stoplight switch connector and the ETACS-ECU connector.

Between C-32 Stoplight switch connector (terminal No.2) and C-304 ETACS-ECU harness-side connector (terminal No.1)

Q. Is the check result normal?

	Go to Step 6.

	Repair the wiring harness.

STEP 6. Check for open circuit or short to ground in wiring harness between the ETACS-ECU connector and the joint connector (4)

Between C-312 ETACS-ECU harness-side connector (terminal No.16) and C-38 joint connector (4) (terminal No.10)

Q. Is the check result normal?

	Go to Step 7.

	Repair the wiring harness.

STEP 7. Check for open circuit in wiring harness between the stoplight switch connector and the joint connector (4)

Between C-32 stoplight switch connector (terminal No.1) and C-38 joint connector (4) (terminal No.10)

Q. Is the check result normal?

	Go to Step 8.

	Repair the wiring harness.

STEP 8. Symptom recheck after erasing diagnosis code

Q. Is the check result normal?

	Intermittent malfunction

	Replace the ETACS-ECU, and then go to Step 9.

STEP 9. Symptom recheck after erasing diagnosis code

Q. Is the check result normal?

	Intermittent malfunction

	Replace TCM.