Circuit Description
This diagnostic test functions on the assumption that a brake application causes a sudden decrease in non-drive wheel speed.
The extended travel brake switch is a normally closed switch. When the extended travel brake switch is closed, the PCM senses ignition voltage on the extended travel brake switch signal circuit.
If the PCM senses voltage on the extended travel brake switch signal circuit when the extended travel brake switch should be open, DTC P1575 will set.
Conditions for Running the DTC
| • | The engine speed is more than 700 RPM. |
| • | The engine has been operating more than 2 seconds. |
| • | The wheel speed must be more than 30 mph in order to enable the diagnostic. The diagnostic will disable when the wheel speed is below 10 mph. |
| • | The vehicle speed is decreasing at a rate more than 16.7 km/h over a 1 second period. |
Conditions for Setting the DTC
| • | The PCM detects voltage on the extended travel brake switch circuit when the extended travel brake switch should be open. |
| • | The above conditions are present for 1.5 seconds. |
Action Taken When the DTC Sets
| • | The PCM stores the DTC information into memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records. |
Conditions for Clearing the DTC
| • | A last test failed current DTC clears when the diagnostic runs and does not fail. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures. |
| • | Use a scan tool in order to clear the DTC or disconnect the PCM battery feed. |
Diagnostic Aids
Important: Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing or replacing the modules. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion into the PCM.
In order to adjust the extended travel brake switch perform the following:
- With the brake pedal pressed, insert the appropriate brake lamp switch into the retainer until the switch body seats in the retainer. You can hear clicks as you push the threaded portion of the switch through the retainer.
- Slowly pull the brake pedal fully rearward against the stop until you can no longer hear the clicks.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step determines if the fault is present.
-
This step checks for a Extended Travel Brake Switch circuit for being shorted to B+.
-
This DTC will not report a pass. The scan tool status for this DTC will never report a pass. The scan tool will only display when the diagnostic fails. The repair is not complete if the scan tool indicates that the diagnostic ran and failed.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Cruise Control Schematics | ||||
1 | Did you perform A Diagnostic System Check-Cruise Control? | -- | Go to Step 2 | |
Does the extended travel brake switch parameter indicate applied? | -- | Go to Diagnostic Aids | Go to Step 3 | |
3 | Check for proper adjustment of the appropriate brake switch. Refer to Diagnostic Aids . Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 4 |
Does the extended travel brake switch parameter indicate released ? | -- | Go to Step 7 | Go to Step 5 | |
5 |
Does the voltage measure greater than the specified value? | 0.5 V | Go to Step 6 | Go to Step 8 |
6 | Repair the short to voltage on the extended travel brake switch signal circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 9 | -- |
7 | Replace the appropriate brake switch. Refer to Stop Lamp Switch Replacement in Lighting Systems. Did you complete the replacement? | -- | Go to Step 9 | -- |
8 |
Important: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls 4.0L Did you complete the repair? | -- | Go to Step 9 | -- |
Does the DTC run and pass? | System OK | Go to Step 2 | ||
