P0573 Brake Switch 1 Stuck Off

P0573 Code - condition the vehicle speed must go above 48 km/h (30 mph) to ensure that the vehicle is in fact moving. APP position cannot exeed a calibrated threshold for longer than a calibrated time. Once the enable conditions are met the diagnostic will wait for the vehicle speed to reach zero. If the Brake switch is off, a fail timer will start to increment.

- The Brake switch 1 fail timer exeeds a calibrated threshold
- MIL light illuminate

Possible causes P0573 Code

• Fused ignition switch output circuit open
• Brake switch 1 signal circuit shorted to ground
• Brake switch 1 signal circuit open
• Brake switch
• Powertrain Control Module (PCM)

Diagnose P0573 Code

Step 1. Check for an active DTC

Turn the ignition on, test drive the vehicle in accordance with the monitoring to set this DTC. With the scan tool, read DTCs and record on the repair order.

Is the DTC active or pending?

Yes, go to step 2.

No, perform the PCM intermittent condition.

Step 2. Check the fused ignition switch output circuit for an open

Turn the ignition off, disconnect the Brake switch harness connector. Turn the ignition on, measure the voltage on the fused ignition switch output circuit at the Brake switch harness connector.

Is the voltage equal to Battery voltage?

Yes, go to step 3.

No, repair the fused ignition switch output circuit for an open. If the fuse is blown, check the fused ignition switch output circuit and Brake switch 1 signal circuit for a short to ground.

Step 3. Brake switch

Reconnect the Brake switch harness connector. Back probe and measure voltage on the Brake switch 1 signal circuit at the Brake switch harness connector with the Brake pedal PRESSED.

Is the voltage reading equal to Battery voltage?

Yes, go to step 4.

No, verify that there is good pin to terminal contact in the switch and Powertrain Control Module harness connectors. If no problems are found, replace the Brake switch.

Step 4. Check the Brake switch 1 signal circuit for a short to ground

Turn the ignition off, disconnect the Brake switch harness connector. check for continuity between ground and Brake switch 1 signal circuit at the Brake switch harness connector.

Is there continuity between ground and the Brake switch 1 signal circuit?

Yes, repair the Brake switch 1 signal circuit for a short to ground.

No, go to step 5.

Step 5. Check the Brake switch 1 signal circuit for an open/high resistance

Disconnect the PCM harness connector, measure the resistance of the Brake switch 1 signal circuit between the Brake switch harness connector and the PCM harness connector.

Is the resistance below 3.0 Ohms?

Yes, go to step 6.

No, repair the Brake switch Battery feed circuit for an open or high resistance.

Step 6. Check related PCM and component connections

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