P0571-BRAKE SWITCH 1 PERFORMANCE

For a complete wiring diagram Refer to Section 8W.

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:
If the output of Brake Switch No.1 to the PCM looks like it is not applied, while Brake Lamp Switch Output circuit is applied the fault will mature in 60ms. One Trip Fault.

Possible Causes

(B15) BRAKE SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO GROUND

(B16) BRAKE SWITCH NO.2 SIGNAL CIRCUIT OPEN

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

(Z904) GROUND 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 properly adjusted before continuing.

NOTE: Make sure the Stop Lamp Switch is properly wired, such as (B15) Brake Switch No.1 and (B16) Brake Switch No.2 Signal circuit are not switched at the harness connector.

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.(B15) BRAKE SWITCH NO.1 SIGNAL SHORTED TO GROUND

Is the resistance below 100 ohms?

Yes

Repair the short to ground in the (B15) Brake Switch No.1 Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Go To 3

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

Is the resistance below 5.0 ohms?

Yes

Go To 4

Repair the open in the (B16) Brake Switch No.2 Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

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

Is the resistance below 100 ohms?

Yes

Repair the short to ground in the (B16) Brake Switch No.2 Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Go To 5

5.(Z904) GROUND CIRCUIT OPEN

Is the resistance below 5.0 ohms?

Yes

Go To 6

Repair the open in the (Z904) Ground circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

6.STOP LAMP SWITCH

Does the resistance change from below 5.0 ohms to an open circuit for one or both of the measurements taken?

Yes

Go To 7

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

7.PCM

NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.

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)