DTC P0703 [L8, LF]

id0102b1809900

DTC P0703

Brake switch input circuit problem
DETECTION CONDITION
•  The PCM monitors changes in input voltage from the brake switch No.1. If the input signal does not change while alternately accelerating and decelerating 8 times, the PCM determines that the brake switch No.1 circuit has a malfunction.
Diagnostic support note
•  This is a continuous monitor (CCM).
•  The MIL illuminates if the PCM detects the above malfunction condition in two consecutive drive cycles or in one drive cycle while the DTC for the same malfunction has been stored in the PCM.
•  PENDING CODE is available if the PCM detects the above malfunction condition during the first drive cycle.
•  FREEZE FRAME DATA (Mode 2/Mode 12) is available.
•  The DTC is stored in the PCM memory.
POSSIBLE CAUSE
Note
•  Inspect the brake switch with it installed to the brake pedal, otherwise the brake switch may not operate normally. If the brake switch is removed from the brake pedal, replace the brake switch with a new one.
•  Brake switch connector or terminals malfunction
•  Open circuit or short to ground in wiring harness between battery positive terminal and brake switch terminal B
―  Short to ground in wiring harness between battery positive terminal and brake switch terminal B
―  STOP 10 A fuse malfunction
―  Open circuit in wiring harness between battery positive terminal and brake switch terminal B
•  Short to ground in wiring harness between brake switch terminal D and PCM terminal 1AB
•  PCM connector or terminals malfunction
•  Short to power supply in wiring harness between brake switch terminal D and PCM terminal 1AB
•  Open circuit in wiring harness between brake switch terminal D and PCM terminal 1AB
•  Brake switch No.1 malfunction
•  PCM malfunction

Diagnostic procedure

STEP

INSPECTION

ACTION
1
VERIFY FREEZE FRAME DATA (MODE 12) HAS BEEN RECORDED
•  Has the FREEZE FRAME DATA (Mode 12) been recorded?
Yes
Go to the next step.
No
Record the FREEZE FRAME DATA (Mode 12) on the repair order, then go to the next step.
2
VERIFY RELATED SERVICE INFORMATION AVAILABILITY
•  Verify related Service Information availability.
•  Is any related Service Information available?
Yes
Perform repair or diagnosis according to the available Service Information.
•  If the vehicle is not repaired, go to the next step.
No
Go to the next step.
3
INSPECT BRAKE SWITCH CONNECTOR AND TERMINALS
•  Turn the ignition switch off.
•  Disconnect the brake switch connector.
•  Inspect for poor connection (such as damaged/pulled-out pins, corrosion).
•  Is there any malfunction?
Yes
Repair or replace the connector or terminals, then go to Step 9.
No
Go to the next step.
4
INSPECT BRAKE SWITCH NO.1 POWER SUPPLY CIRCUIT FOR OPEN CIRCUIT OR SHORT TO GROUND
•  Brake switch connector is disconnected.
•  Turn the ignition switch to the ON position (engine off).
•  Measure the voltage between brake switch terminal B (wiring harness-side) and body ground.
•  Is the voltage B+?
Yes
Go to the next step.
No
Inspect the STOP 10 A fuse.
•  If the fuse is melt:
―  Repair or replace the wiring harness for a possible short to ground.
―  Replace the fuse.
•  If the fuse is deterioration:
―  Replace the fuse.
•  If the fuse is normal:
―  Repair or replace the wiring harness for a possible open circuit.
Go to Step 9.
5
INSPECT BRAKE SWITCH NO.1 SIGNAL CIRCUIT FOR SHORT TO GROUND
•  Brake switch connector is disconnected.
•  Turn the ignition switch off.
•  Inspect for continuity between brake switch terminal D (wiring harness-side) and body ground.
•  Is there continuity?
Yes
If the short to ground circuit could be detected:
•  Repair or replace the wiring harness for a possible short to ground.
If the short to ground circuit could not be detected:
•  Replace the PCM (short to ground in PCM internal circuit).
Go to Step 9.
No
Go to the next step.
6
INSPECT PCM CONNECTOR AND TERMINALS
•  Disconnect the PCM connector.
•  Inspect for poor connection (such as damaged/pulled-out pins, corrosion).
•  Is there any malfunction?
Yes
Repair or replace the connector or terminals, then go to Step 9.
No
Go to the next step.
7
INSPECT BRAKE SWITCH NO.1 SIGNAL CIRCUIT FOR SHORT TO POWER SUPPLY
•  Brake switch and PCM connectors are disconnected.
•  Turn the ignition switch to the ON position (engine off).
•  Measure the voltage between brake switch terminal D (wiring harness-side) and body ground.
•  Is there any voltage?
Yes
Repair or replace the wiring harness for a possible short to power supply, then go to Step 9.
No
Go to the next step.
8
INSPECT BRAKE SWITCH NO.1 SIGNAL CIRCUIT FOR OPEN CIRCUIT
•  Brake switch and PCM connectors are disconnected.
•  Turn the ignition switch off.
•  Inspect for continuity between brake switch terminal D (wiring harness-side) and PCM terminal 1AB (wiring harness-side).
•  Is there continuity?
Yes
Replace the brake switch, then go to the next step.
(See BRAKE PEDAL REMOVAL/INSTALLATION.)
No
Repair or replace the wiring harness for a possible open circuit, then go to the next step.
9
VERIFY DTC TROUBLESHOOTING COMPLETED
•  Make sure to reconnect all disconnected connectors.
•  Clear the DTC from the PCM memory using the M-MDS.
•  Drive the vehicle 30 km/h {18.6 mph} or more.
•  Depress and release the brake pedal more than 8 times while driving vehicle.
•  Perform the Pending Trouble Code Access Procedure.
•  Is the PENDING CODE for this DTC present?
Yes
Replace the PCM, then go to the next step.
(See PCM REMOVAL/INSTALLATION [L8, LF].)
No
Go to the next step.
10
VERIFY AFTER REPAIR PROCEDURE
•  Perform the “AFTER REPAIR PROCEDURE”.
•  Are any DTCs present?
Yes
Go to the applicable DTC troubleshooting.
(See DTC TABLE [L8, LF].)
No
DTC troubleshooting completed.