P0703
P0703-BRAKE SWITCH 2 PERFORMANCE
For a complete wiring diagram refer to: Electrical Diagrams
When Monitored
Ignition on.
Set Condition
When the PCM recognizes Brake Switch No.2 voltage is not equal to the applied value at the PCM when Brake Switch No. 1 is applied. This could be a normal condition. If this condition is seen repeatedly by the PCM the fault is set. Cruise will not work for the rest of the key cycle.
Possible Causes
- (A103) FUSED B+ CIRCUIT
- (L50) BRAKE LAMP SWITCH OUTPUT CIRCUIT OPEN
- (L50) BRAKE LAMP SWITCH OUTPUT CIRCUIT SHORTED TO BATTERY VOLTAGE
- (L50) BRAKE LAMP SWITCH OUTPUT CIRCUIT SHORTED TO GROUND
- (B29) BRAKE SWITCH NO.1 SIGNAL CIRCUIT OPEN
- STOP LAMP SWITCH
- PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.
Diagnostic Test
1. ACTIVE DTC
NOTE: Make sure the Stop Lamp Switch is adjusted properly before continuing.
NOTE: Make sure the Stop Lamp Switch is properly wired, such as (B29) Brake Switch No.1 and (L50) Brake Lamp Switch Output are not switched at the harness connector.
Ignition on, engine not running.
With a scan tool, read DTCs.
Is the DTC active at this time?
Yes >> Go To 2
No >> Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
2. (A103) FUSED B+ CIRCUIT
Turn the ignition off.
Disconnect the Stop Lamp Switch harness connector.
Using a 12-volt test light connected to ground, probe the (A103) Fused B+ circuit in the Stop Lamp Switch harness connector.
Does the test light illuminate brightly?
Yes >> Go To 3
No >> Repair the open or short to ground in the (A103) Fused B+ circuit. Inspect the related fuse and repair as necessary
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
3. STOP LAMP SWITCH
Turn the ignition off.
Measure the resistance between the (A103) Fused B+ circuit terminal and the (L50) Brake Lamp Switch Output terminal in the Stop Lamp Switch.
Measure the resistance between the (Z429) Ground circuit terminal and the (K29) Brake Switch No.1 Signal terminal in the Stop Lamp Switch.
Apply and release the brake pedal while monitoring the ohmmeter.
Does the resistance change from below 5.0 ohms to open circuit for each circuit check?
Yes >> Go To 4
No >> Replace the Stop Lamp Switch.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
4. (L50) BRAKE LAMP SWITCH OUTPUT CIRCUIT SHORTED TO BATTERY VOLTAGE
Disconnect the PCM harness connectors.
Measure the voltage on the (L50) Brake Lamp Switch Output circuit in the Stop Lamp Switch harness connector.
Ignition on, engine not running.
Is the voltage above 1.0 volt?
Yes >> Repair the short to battery voltage in the (L50) Brake Lamp Switch Output circuit.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Go To 5
5. (L50) BRAKE LAMP SWITCH OUTPUT CIRCUIT OPEN
Turn the ignition off.
Measure the resistance of the (L50) Brake Lamp Switch Output circuit from the Stop Lamp Switch harness connector to the C1 FCM harness connector.
Is the resistance below 5.0 ohms?
Yes >> Go To 6
No >> Repair the open in the (L50) Brake Lamp Switch Output circuit.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
6. (L50) BRAKE LAMP SWITCH OUTPUT CIRCUIT SHORTED TO GROUND
Measure the resistance between ground and the (L50) Brake Lamp Switch Output circuit in the Stop Lamp Switch harness connector.
Is the resistance below 5.0 ohms?
Yes >> Repair the short to ground in the (L50) Brake Lamp Switch Output circuit.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Go To 7
7. (B29) BRAKE SWITCH NO.1 SIGNAL CIRCUIT OPEN
Measure the resistance of the (B29) Brake Switch No.1 Signal circuit from the Stop Lamp Switch harness connector to the appropriate terminal of special tool #8815.
Is the resistance below 5.0 ohms?
Yes >> Go To 8
No >> Repair the open in the (B29) Brake Switch No.1 Signal circuit.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
8. PCM
NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.
Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.
Were there any problems found?
Yes >> Repair as necessary
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Replace and program the Powertrain Control Module per Service Information.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test