Circuit Description
The brake switch, torque converter clutch (TCC) and cruise control release switch is used as an input to the Transmission Control Module (TCM) to indicate the status of the brake pedal; applied or released.
The normally closed TCC brake switch contacts supplies an ignition voltage input to the TCM at terminal X1-38. Applying the brakes, the switch contacts open, interrupting the voltage supply to the TCM. Releasing the brakes, the contacts close and voltage is reapplied to TCM terminal X1-38.
When the TCM senses 0 voltage at terminal X1-38, the TCM de-energizes the TCC solenoid valve.
If the TCM detects an open in the TCC brake switch circuit (stuck on condition) during acceleration, then DTC P0572 sets, which is a type 'C' DTC.
Conditions for Running the DTC
| • | Ignition voltage is between 8-18 volts. |
| • | Engine speed is between 450-6,800 RPM for at least 5 seconds. |
Conditions for Setting the DTC
The brake switch is not detected as on in the time of 6.25 minutes without going on.
Action Taken When the DTC Sets
| • | The TCM stores DTC P0563 into TCM history. |
| • | TCM inhibits autograde braking. |
Conditions for Clearing the DTC
| • | Tech 2 can clear the DTC. |
| • | The TCM clears the DTC from its memory (history DTC) if the vehicle completes 40 warm-up cycles without a non-emission related DTC occurring. |
| • | The TCC brake switch input indicates ignition voltage for 2 seconds. |
| • | The TCM cancels the DTC default actions when the fault no longer exists and the DTC passes. |
Diagnostic Aids
- Inspect the wiring at the TCM, the brake switch connector and all other circuit connecting points for the following conditions:
- When diagnosing for an intermittent short or open condition, massage the wiring harness while watching the test equipment for a change.
- Inspect the brake switch for proper mounting and operation.
| • | A backed out terminal |
| • | A damaged terminal |
| • | Reduced terminal tension |
| • | A chafed wire |
| • | A broken wire inside the insulation |
| • | Moisture intrusion |
| • | Corrosion |
Test Description
The number below refers to the step number on the diagnostic table.
2. Disconnecting the brake switch connector and jumping the circuit while observing a status change on the Tech 2, isolates the brake switch as the source of the DTC.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Automatic Transmission Controls Schematics For information on testing wiring faults, refer to Wiring Systems. | |||
1 | Has the Diagnostic System Check - Automatic Transmission been completed? | Go to Step 2 | |
2 |
Did the TCC Brake Switch status change from Closed to Open? | Go to Step 3 | Go to Step 4 |
3 | Replace the TCC Brake Switch. Refer to Stop Lamp Switch Replacement. Is replacement complete? | Go to Step 6 | -- |
4 | Check circuit 640 for open circuit condition between brake switch connector S220, terminal X1-A and fuse F5. Was an open circuit condition found? | Repair open circuit condition. Go to Step 6 | Go to Step 5 |
5 | Replace TCM. Refer to Transmission Control Module Replacement for replacement procedures. Is the replacement complete? | Go to Step 6 | -- |
6 | Perform the following procedure to verify the repair:
Does the test run and pass? | System OK | Go to Step 2 |
When all diagnosis and repairs are completed, clear all DTCs and verify correct operation. | |||
