LEMON Manuals: Even more car manuals for everyone
Home >> Toyota >> 2001 >> Sienna CE >> Repair and Diagnosis >> External Pages >> Different car >> Section 98 (Engine Controls - Self-Diagnostics) >> Diagnostic Tests >> DTC P0504: Brake Switch "A" /"B" Correlation >> Diagnosis & Repair

Diagnosis & Repair

WARNING: This page is about a different car, the 2003 Lexus LS 430. However, it is still accessible from the selected car via links, so may be relevant.
  1. Check if the stop lights go on and off normally when the brake pedal is operated and released. If okay, go to next step. If not okay, repair stop light circuit.
  2. If using hand-held tester, connect the hand-held tester to the DLC3. Turn the ignition switch ON and push the hand-held tester switch ON. Read the STP signal on the hand-held tester. With brake pedal depressed, STP signal should be ON. With brake pedal released, STP signal should be OFF.
    Fig 1: Checking STP Signal
    G00165157Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  3. If not using hand-held tester, remove the engine room ECU cover. Turn the ignition switch ON. Check voltage between terminal STP of the ECM and body ground. With brake pedal depressed, voltage should be 7.5-14 volts. With brake pedal released, voltage should be below 1.5 volts. See Fig 1. If okay, check for intermittent problems. If not okay, go to next step.
  4. Check stop light switch. Replace stop light switch as necessary. If okay, go to next step.
  5. Check harness and connector between ECM and stop light switch. Repair as necessary. If okay, replace ECM.
scientia non olet · About LEMON Manuals