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 (ETBS) is a normally closed switch. When the extended travel brake switch is closed, the powertrain control module (PCM) senses ignition voltage on the extended travel brake switch signal circuit.
If the PCM senses a 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 48 km/h (30 mph) in order to enable the diagnostic. The diagnostic will disable when the wheel speed is below 16.1 km/h (10 mph). |
| • | The vehicle speed is decreasing at a rate more than 16.7 km/h (10.4 mph) over a one 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 control module stores the DTC information into memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records. |
| • | The driver information center, if equipped, may display a message. |
Conditions for Clearing the DTC
| • | A current DTC Last Test Failed clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic. |
| • | Clear the DTC with a scan tool. |
Diagnostic Aids
Important: Remove any debris from the PCM/TAC module connector surfaces before servicing the PCM/TAC module. Inspect the PCM/TAC module connector gaskets when diagnosing/replacing the modules. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion into the PCM/TAC modules.
In order to adjust the extended travel brake switch perform the following:
- With the brake pedal depressed, insert the 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 the extended travel brake switch circuit for being shorted to B+.
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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: Engine Controls Schematics | ||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |
Does the display indicate applied? | -- | Go to Diagnostic Aids | Go to Step 3 | |
3 | Check the adjustment of the extended brake travel switch. Refer to Diagnostic Aids. Was an adjustment necessary? | -- | Go to Step 9 | Go to Step 4 |
Does the display indicate applied? | -- | Go to Step 7 | Go to Step 5 | |
5 |
Is the voltage more than the specified value? | 0.5 V | Go to Step 6 | Go to Step 8 |
6 | Repair the short to voltage on the extended brake travel switch signal circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 9 | -- |
7 | Replace the extended brake travel switch. Refer to Stop Lamp Switch Replacement in Hydraulic Brakes. Is the action complete? | -- | Go to Step 9 | -- |
8 | Replace the PCM. Refer to Powertrain Control Module Replacement Did you complete the replacement? | -- | Go to Step 9 | -- |
Does the DTC run and pass? | Go to Step 10 | Go to Step 2 | ||
10 | With a scan tool, observe the stored information, Capture Info. Are any DTCs displayed that you have not diagnosed? | -- | System OK | |
