DTC P0572 or P0573
Diagnostic Instructions
DTC Descriptors
| DTC P0572: Brake Switch Circuit 1 Low
Voltage |
| DTC P0573: Brake Switch Circuit 1 High
Voltage |
Diagnostic Fault Information
Circuit
|
Short to Ground
|
Open/High Resistance
|
Short to Voltage
|
Signal Performance
|
Stop Lamp Switch Signal
|
P0572
|
P0572
|
P0573
|
-
|
|
| |
Circuit/System Description
The stop lamp switch signal circuit is a B+ input from the body
control module (BCM) to the engine control module (ECM). The ECM
monitors the stop lamp switch circuit to detect when the brake
pedal has been applied. The BCM monitors the brake pedal position
sensor to determine when the brake pedal is applied. When the brake
pedal is applied, the BCM supplies B+ on the stop lamp switch
signal circuit and also sends a serial data message to the ECM
indicating that the brake pedal has been applied.
Conditions for Running the DTC
| • |
Battery voltage is greater
than 11.5 V. |
Conditions for Setting the DTC
The ECM detects either a low voltage signal on the stop lamp
switch signal circuit when the serial data message from the BCM
indicates the brakes are applied, or a high voltage signal on the
stop lamp switch signal circuit when the serial data message from
the BCM indicates the brakes are not applied.
Action Taken When the DTC Sets
| • |
The malfunction indicator lamp
(MIL) will not illuminate. |
| • |
The cruise control system is
disabled. |
Conditions for Clearing the DTC
| • |
The condition responsible for
setting the DTC no longer exists. |
| • |
A history DTC will clear after
40 malfunction-free ignition cycles have occurred. |
Reference Information
Schematic Reference
Cruise Control Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
Cruise Control Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Testing
| 1. |
Ignition OFF, disconnect the
X1 harness connector at the K20 Engine Control Module. |
| 2. |
Connect a test lamp between
the appropriate signal circuit terminal listed below and
ground. |
| |
• |
Terminal 25 (LDD, LDE, LLU,
LPL, LPV) |
| 3. |
Ignition ON, verify the test
lamp turns ON and OFF when pressing and releasing the brake
pedal. |
| ⇒ |
If the test lamp is always ON, test the signal
circuit for a short to voltage. If the circuit tests normal,
replace the K9 Body Control Module. |
| ⇒ |
If the test lamp is always OFF, test the signal
circuit for a short to ground or an open/high resistance. If the
circuit tests normal, replace the K9 Body Control Module. |
| 4. |
If all circuits test normal,
replace the K20 Engine Control Module. |
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic
procedure.
Control Module References for control module replacement,
programming and setup
|
