P0703-BRAKE SWITCH 2 PERFORMANCE

For a complete wiring diagram Refer to Section 8W.

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

(F941) FUSED IGNITION SWITCH OUTPUT CIRCUIT

(B16) BRAKE SIGNAL 2 CIRCUIT OPEN

(B16) BRAKE SIGNAL 2 CIRCUIT SHORTED TO BATTERY VOLTAGE

(B16) BRAKE SIGNAL 2 CIRCUIT SHORTED TO GROUND

(B15) BRAKE SIGNAL 1 CIRCUIT OPEN

STOP LAMP SWITCH

PCM

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).

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 (B15) Brake Signal 1 and (B16) Brake Signal 2 circuit are not switched at the harness connector.

Ignition on, engine not running.
With a scan tool, select View DTCs.

Is the DTC Active at this time?

Yes

Go To 2

Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

2. (F941) FUSED IGNITION SWITCH CIRCUIT

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

Does the test light illuminate brightly?

Yes

Go To 3

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. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

3. STOP LAMP SWITCH

Turn the ignition off.
Measure the resistance between the (F941) Fused Ignition Switch Output circuit terminal and the (B16) Brake Signal 2 circuit terminal in the Stop Lamp Switch.
Measure the resistance between the (Z914) Ground circuit terminal and the (B15) Brake Signal 1 terminal in the Stop Lamp Switch.
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

Replace the Stop Lamp Switch.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

4. (B16) BRAKE SIGNAL 2 CIRCUIT SHORTED TO BATTERY VOLTAGE

Disconnect the C3 PCM harness connector.
Measure the voltage on the (B16) Brake Signal 2 circuit in the Stop Lamp Switch harness connector.
Ignition on, engine not running.

Is the voltage above 0 volts?

Yes

Repair the short to battery voltage in the (B16) Brake Signal 2 circuit.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Go To 5

5. (B16) BRAKE SIGNAL 2 CIRCUIT OPEN

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 Miller Special Tool #8815 to perform diagnosis.

Measure the resistance of the (B16) Brake Signal 2 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 6

Repair the open in the (B16) Brake Signal 2 circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

6. (B16) BRAKE SIGNAL 2 CIRCUIT SHORTED TO GROUND

Measure the resistance between ground and the (B16) Brake Signal 2 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 Signal 2 circuit.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Go To 7

7. (B15) BRAKE SIGNAL 1 CIRCUIT OPEN

Measure the resistance of the (B15) Brake Signal 1 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

Repair the open in the (B15) Brake Signal 1 circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

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 the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Replace and program the Powertrain Control Module per Service Information.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)