DTC P0571 7.8L
Circuit Description
The torque converter clutch (TCC) brake switch/cruise control release signal circuit is incorporated into the stop lamp switch. The TCC brake switch/cruise control release signal circuit portion of the stop lamp switch is a normally closed switch. The stop lamp switch signal circuit portion of the stop lamp switch is a normally open switch. When the brake pedal is released, the ECM detects a high voltage signal on the TCC brake switch/cruise control release signal circuit and a low signal voltage signal on the stop lamp switch signal circuit.
Conditions for Running the DTC
| • | The ignition is ON. |
| • | The traction control system or the antilock brake system have not failed. |
Conditions for Setting the DTC
| • | When the brake pedal is released, the ECM detects a high voltage signal on the stop lamp switch signal circuit or when the ECM detects a low voltage signal on the TCC brake switch/cruise control release signal circuit. |
| • | The above conditions are present for 1.5 seconds. |
Action Taken When the DTC Sets
| • | The ECM stores the DTC information into memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The ECM records the operating conditions at the time the diagnostic fails. The ECM stores this information in the Failure Records. |
Conditions for Clearing the DTC
| • | A last test failed, or current DTC, clears when the diagnostic runs and does not fail. |
| • | A history DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic. |
| • | Use a scan tool in order to clear the DTC. |
Diagnostic Aids
Refer to Exterior Lighting Systems Description and Operation in Lighting Systems, in order to avoid a misdiagnosis.
For an intermittent, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Cruise Control Schematics Connector End View Reference: Lighting Systems Connector End Views | |||
1 | Did you perform the Cruise Control Diagnostic System Check? | Go to Step 2 | |
2 |
Does the test lamp illuminate? | Go to Step 3 | Go to Step 4 |
3 | Test the stop lamp switch signal circuit for a short to voltage. Refer Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 6 |
4 | Test the TCC brake switch/cruise control release signal circuit for a an open or for a high resistance. Refer Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 5 |
5 | Inspect for poor connections at the harness connector of the stop lamp switch. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 7 |
6 | Inspect for poor connections at the harness connector of the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 8 |
7 | Replace the stop lamp switch. Refer to Stop Lamp Switch Replacement in Lighting Systems. Did you complete the repair? | Go to Step 9 | -- |
8 |
Important: Program the replacement ECM. Replace the ECM. Refer to Engine Control Module Replacement/Restore Fuel Rate Data in Engine Controls - 7.8 L. Did you complete the replacement? | Go to Step 9 | -- |
9 |
Does the DTC reset? | Go to Step 2 | System OK |
