DTC Descriptor
DTC P1574 00 : Stop Lamp Switch Circuit
Diagnostic Fault Information
Perform the
Diagnostic System Check - Vehicle
prior to using this diagnostic procedure.
Circuit/System Description
This diagnostic test functions on the assumption that a sudden decrease in vehicle speed is caused by a brake pedal application. When the powertrain control module (PCM) detects that there is a 4.2 km/h (2.6 mph) or greater decrease in vehicle
speed within 0.25 second and a transition of the torque converter clutch (TCC) brake switch without a transition of the stop lamp switch, the PCM sets DTC P1574.
Conditions for Running the DTC
| • | DTCs P0502, P0503, P0719, and P0724 are not set. |
| • | The engine speed is greater than 700 RPM. |
| • | The traction control system or the antilock brake system are not active and have not failed. |
| • | The vehicle speed is greater than 48 km/h (30 mph) in order to enable the diagnostic. |
| • | The diagnostic will disable when the wheel speed is less than 16 km/h (10 mph). |
Conditions for Setting the DTC
| • | The vehicle speed decreases by at least 4.2 km/h (2.6 mph) within 0.25 second. |
| • | The PCM detects a TCC brake transition. |
| • | The PCM does not detect a stop lamp switch transition. |
Action Taken When the DTC Sets
| • | The PCM sets the stop lamp switch status to released. |
| • | The PCM disables the operation of the cruise control system. |
Conditions for Clearing the DTC
| • | The history DTC clears after 40 malfunction-free warm-up cycles. |
| • | The DTC becomes history when the conditions for setting the DTC are no longer present. |
| • | The PCM receives the clear code command from the scan tool. |
Diagnostic Aids
Reference Information
Schematic Reference
Cruise Control Schematics
Connector End View Reference
Lighting Systems Connector End Views
Electrical Information Reference
Scan Tool Reference
Scan Tool Data List
Circuit/System Verification
Ignition ON, observe the Stop Lamp Pedal Switch parameter while applying and releasing the brake pedal. The reading should change between Applied/Released, and all brake lights should turn ON and OFF accordingly.
Circuit/System Testing
Ignition ON, observe the Stop Lamp Pedal Switch parameter.
| ⇒ | If the parameter reads Applied, refer to
Stop Lamps Always On
. If the stop lamps operate normal, replace the PCM. |
| ⇒ | If the parameter reads Released, test the stop lamp switch
signal circuit for an open/high resistance. If circuit tests normal, replace the PCM. |
Repair Instructions
Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.
Control Module References
for PCM module replacement, setup, and programming
