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 engine control module (ECM) detects ignition voltage on the extended travel brake switch signal circuit.
If the ECM detects voltage on the extended travel brake switch signal circuit when the extended travel brake switch should be open, this DTC sets.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P1575 Extended Travel Brake Switch Failure
Conditions for Running the DTC
| • | The engine speed is greater than 700 RPM. |
| • | The engine has been operating longer than 2 seconds. |
| • | The wheel speed must be greater 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 greater than 2.6 mph over a 250 millisecond period. |
Conditions for Setting the DTC
| • | The ECM detects voltage on the extended travel brake switch circuit when the extended travel brake switch should be open. |
| • | The above condition is present for 1.5 seconds. |
Diagnostic Aids
An improperly adjusted extended travel brake switch may cause this DTC to set. In order to avoid misdiagnosis, verify that the extended travel brake switch is properly adjusted. Refer to Stop Lamp Switch Adjustment in Lighting Systems.
Step
| Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic Reference: Cruise Control Schematics | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
2 |
Does the Extended Brake Travel Switch parameter display Released? | -- | Go to Step 3 | Go to Step 6 |
3 |
Does the Extended Brake Travel Switch parameter display Applied? | -- | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 4 |
4 |
Does the Extended Brake Travel Switch parameter display Applied? | -- | Go to Step 11 | Go to Step 5 |
5 |
Does the voltage measure more than the specified value? | 0.5 V | Go to Step 8 | Go to Step 13 |
6 |
Does the test lamp illuminate? | -- | Go to Step 7 | Go to Step 9 |
7 |
Does the Extended Brake Travel Switch parameter display Released? | -- | Go to Step 11 | Go to Step 10 |
8 | 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 15 | -- |
9 | Repair the open, short to ground, or high resistance on the ignition 1 voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 15 | -- |
10 | Test the extended travel brake switch signal circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 15 | Go to Step 13 |
11 | Inspect for poor connections at the extended travel brake switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 12 |
12 | Replace the Extended Travel Brake switch. Refer to Stop Lamp Switch Replacement in Lighting Systems. Did you complete the replacement? | -- | Go to Step 15 | -- |
13 | Inspect for a poor connection at the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 14 |
14 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | -- | Go to Step 15 | -- |
15 |
Does the DTC set? | -- | Go to Step 2 | -- |
