DTC P0703 [LF]

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DTC P0703 [LF]

B3E010201089W01

DTC P0703 | Brake switch input circuit problem
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DETECTION CONDITION

• The PCM monitors changes in input voltage from the brake switch. If the PCM does not detect PCM terminal 1AU voltage changes while alternately accelerating and decelerating 8 times, the PCM determines that brake switch circuit has 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 first drive cycle.
• FREEZE FRAME DATA is available.
• The DTC is stored in the PCM memory.

POSSIBLE CAUSE

• Brake switch malfunction
• Poor connection of brake switch connector or PCM connector
• Short to power supply in wiring harness between brake switch terminal D and PCM connector terminal 1AU
• Open circuit in wiring harness between brake switch terminal D and PCM connector terminal 1AU
• Open circuit in wiring harness between battery positive terminal and brake switch terminal A
• PCM malfunction

Diagnostic procedure

STEP | INSPECTION | ACTION
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1 | VERIFY FREEZE FRAME DATA HAS BEEN RECORDED • Has FREEZE FRAME DATA been recorded? | Yes | Go to the next step.
No | Record the FREEZE FRAME DATA on repair order, then go to the next step.
2 | VERIFY RELATED REPAIR INFORMATION AVAILABILITY • Verify related service repair information availability. • Is any related repair information available? | Yes | Perform repair or diagnosis according to the available repair information. • If the vehicle is not repaired, go to the next step.
No | Go to the next step.
3 | CLASSIFY HIGH INPUT OR LOW INPUT • Connect the WDS or equivalent to DLC-2. • Access BOO PID. • Verify BOO PID during brake pedal operation. • Is BOO PID always OFF? | Yes | Go to the next step.
No | Go to Step 10.
4 | INSPECT BRAKE SWITCH CONNECTOR FOR POOR CONNECTION • Turn the ignition switch off. • Disconnect the brake switch connector. • Inspect for poor connection (such as damaged/pulled-out pins, corrosion). • Is there malfunction? | Yes | Repair or replace the terminal, then go to Step 14.
No | Go to the next step.
5 | CLASSIFY BRAKE SWITCH OR CIRCUIT • Connect the WDS or equivalent to DLC-2. • Access BOO PID. • Connect a jumper wire between brake switch terminal A and D. • Is BOO PID on? | Yes | Go to the next step.
No | Go to Step 7.
6 | INSPECT BRAKE SWITCH • Perform brake switch inspection. (See BRAKE SWITCH INSPECTION.) • Is brake switch normal? | Yes | Go to Step 14.
No | Replace brake switch, then go to Step 14.
7 | INSPECT BRAKE SWITCH POWER CIRCUIT FOR OPEN CIRCUIT • Measure the voltage between brake switch terminal A and body ground. • Is the voltage B+? | Yes | Go to the next step.
No | Repair or replace brake switch power circuit for open, then Go to Step 14.
8 | INSPECT PCM CONNECTOR FOR POOR CONNECTION • Turn the ignition switch off. • Disconnect the PCM connector. • Inspect for poor connection (such as damaged/pulled-out pins, corrosion). • Is there malfunction? | Yes | Repair or replace the terminal, then go to Step 14.
No | Go to the next step.
9 | INSPECT BRAKE SWITCH SIGNAL CIRCUIT FOR OPEN CIRCUIT • Inspect for continuity between brake switch terminal D and PCM terminal 1AU. • Is there continuity? | Yes | Repair or replace wiring harness for open circuit, then go to Step 14.
No | Go to Step 14.
10 | INSPECT BRAKE SWITCH CONNECTOR FOR POOR CONNECTION • Turn the ignition switch off. • Disconnect the brake switch connector. • Inspect for poor connection (such as damaged/pulled-out pins, corrosion). • Is there malfunction? | Yes | Repair or replace the terminal, then go to Step 14.
No | Go to the next step.
11 | CLASSIFY BRAKE SWITCH OR CIRCUIT • Connect the WDS or equivalent to DLC-2. • Access BOO PID. • Verify that BOO PID changes from ON to OFF when brake switch connector disconnected. • Does BOO PID change from ON to OFF? | Yes | Go to the next step.
No | Go to Step 13.
12 | INSPECT BRAKE SWITCH • Perform brake switch inspection. (See BRAKE SWITCH INSPECTION.) • Is brake switch normal? | Yes | Go to Step 14.
No | Replace the brake switch, then go to Step 14.
13 | INSPECT BRAKE SWITCH SIGNAL CIRCUIT FOR SHORT TO POWER SUPPLY • Measure the voltage between brake switch terminal D and body ground. • Is the voltage B+? | Yes | Repair or replace the wiring harness for short to power supply, then go to the next step.
No | Go to the next step.

14

VERIFY TROUBLESHOOTING OF DTC P0703 COMPLETED
• Make sure to reconnect all disconnected connectors.
• Clear the DTC from the memory using the WDS or equivalent.
• Drive the vehicle 30 km/h {18.6 mph} or more.
• Depress and release the brake pedal more than 8 times while driving vehicle.
• Is the PENDING CODE for this DTC present?

Yes

Replace the PCM, then go to the next step.
(See PCM REMOVAL/INSTALLATION [LF].)

No | Go to the next step.
15 | VERIFY AFTER REPAIR PROCEDURE • Perform the "After Repair Procedure". (See AFTER REPAIR PROCEDURE [LF].) • Are any DTC present? | Yes | Go to the applicable DTC troubleshooting. (See DTC TABLE [LF].)
No | Troubleshooting completed.