P0703

P0703-BRAKE SWITCH 2 PERFORMANCE

Special Tools:










For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation

The brake switch rationality checks both failure modes of the brake switch. The brake switch stuck on test checks for a high vehicle speed condition where the brake switch is unexpectedly depressed. The brake switch stuck off test checks for repeated vehicle stop maneuvers without the brake switch depressed.

- When Monitored:
Ignition on.

- Set Condition:
When the Powertrain Control Module (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.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

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 (B15) Brake Switch No.1 and (B16) Brake Lamp Switch Output are not switched at the harness connector.

1. Ignition on, engine not running.
2. With the scan tool, select View DTCs.

Is the DTC Active at this time?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test

2. (F941) FUSED IGNITION SWITCH OUTPUT CIRCUIT




1. Turn the ignition off.
2. Disconnect the Stop Lamp Switch harness connector.
3. Using a 12-volt test light connected to ground, probe the (F941) Fused Ignition Switch Output circuit in the Stop Lamp Switch harness connector.
4. Turn the ignition on.

Does the test light illuminate brightly?

Yes

- Go To 3

No

- Repair the open or short to ground in the (F941) Fused Ignition Switch Output circuit. Inspect the related fuse and repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

3. STOP LAMP SWITCH
1. Turn the ignition off.
2. Measure the resistance between the (F941) Fused Ignition Switch circuit terminal and the (B16) Brake Switch No.2 Signal terminal in the Stop Lamp Switch.
3. Measure the resistance between the (Z910) Ground circuit terminal and the (B15) Brake Switch No.1 Signal terminal in the Stop Lamp Switch.
4. Apply and release the Stop Lamp Switch 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. Stop Lamp Switch - Removal.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

4. (B16) BRAKE SWITCH NO.2 SIGNAL CIRCUIT SHORTED TO VOLTAGE




1. Disconnect the C3 PCM harness connector.
2. Ignition on, engine not running.
3. Measure the voltage on the (B16) Brake Switch No.2 Signal circuit in the Stop Lamp Switch harness connector.

Is there any voltage present?

Yes

- Repair the short to voltage in the (B16) Brake Switch No.2 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 5

5. (B16) BRAKE SWITCH NO.2 SIGNAL CIRCUIT OPEN




1. Turn the ignition off.

CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install the PCM Pinout Box (8815A) to perform diagnosis.

2. Measure the resistance of the (B16) Brake Switch No.2 Signal circuit from the Stop Lamp Switch harness connector to the appropriate terminal of PCM Pinout Box.

Is the resistance below 5.0 Ohms?

Yes

- Go To 6

No

- Repair the open in the (B16) Brake Switch No.2 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

6. (B16) BRAKE SWITCH NO.2 SIGNAL CIRCUIT SHORTED TO GROUND




1. Measure the resistance between ground and the (B16) Brake Switch No.2 Signal circuit in the Stop Lamp Switch harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Repair the short to ground in the (B16) Brake Switch No.2 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 7

7. (B15) BRAKE SWITCH NO.1 SIGNAL CIRCUIT OPEN




1. Measure the resistance of the (B15) Brake Switch No.1 Signal circuit from the Stop Lamp Switch harness connector to the appropriate terminal of PCM Pinout Box.

Is the resistance below 5.0 Ohms?

Yes

- Go To 8

No

- Repair the open in the (B15) Brake Switch No.1 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

8. POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Stop Lamp Switch and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the Switch and Powertrain Control Module connectors.
4. Perform any Technical Service Bulletins that may apply.

Were there any problems found?

Yes

- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Replace and program the Powertrain Control Module. PCM/ECM/TCM Reprogramming
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.