Circuit Description
The stoplamp switch is a normally open switch. The switch receives a
fused battery voltage, and grounds through a pull-up resistor in the Turn/Hazard
Flasher Module. With the brake pedal NOT applied, the Turn/Hazard Flasher
module should detect a low signal voltage on the stoplamp switch circuit.
The Turn/Hazard Flasher module sends the input state of the switch to the
PCM via class 2 serial data. The PCM uses the data to determine the condition
of the switch. With the brakes applied, the PCM compares the stoplamp switch
input to the TCC and/or extended travel brake switch input. If a transition
occurs on the TCC and/or extended travel brakes switches without a transition
on the stoplamp switch, DTC P1574 will set.
Conditions for Running the DTC
| • | Engine Speed is greater than 500 RPM. |
| • | No VSS, TCC brake switch, extended travel brake switch, or EBCM
Serial Data DTCs are set. |
| • | Traction control and antilock brake systems have not failed. |
| • | Traction control and antilock brake systems are not active. |
| • | VSS achieves 32 km/h (20 mph) and remains above 5 km/h (3 mph). |
| • | The difference in speed between the driven wheels and the non-driven
wheels is less than 10 km/h (6 mph). |
Conditions for Setting the DTC
The PCM detects a signal transition on the TCC and/or extended travel
brake switches without a transition on the stoplamp switch
Action Taken When the DTC Sets
| • | The PCM will not illuminate the malfunction indicator lamp (MIL). |
| • | PCM disables cruise control. |
| • | PCM will set the stoplamp switch status to brakes not applied. |
| • | The PCM will store conditions which were present when the DTC
set as Failure Records only. |
Conditions for Clearing the DTC
| • | The PCM will request that the message be turned OFF after one
diagnostic test has been run and passed. |
| • | The History DTC will be cleared after 40 consecutive warm-up cycles
have occurred without a malfunction. |
| • | The DTC can be cleared by using the scan tool Clear DTC Information
function. |
