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Diagnostic Procedure

WARNING: This page is about a different car, the 2002 Toyota Avalon and 2001 Toyota Avalon. However, it is still accessible from the selected car via links, so may be relevant.
  1. Inspect operation of brakelights while applying brake pedal. If brakelight operation is okay, go to next step. If brakelight operation is not okay, check and repair as needed. If brakelight switch is suspect, see BRAKELIGHT SWITCH  under COMPONENT TESTS.
  2. If the TOYOTA scan tool is available, go to next step. If the TOYOTA scan tool is not available, Turn the ignition to the ON position. Access the ECM. See Figure. Using DVOM, measure voltage by backprobing between ECM 22-pin harness connector E8 terminal No. 15 and ground. See Figure. Voltage should be 7.5-14 volts with brake pedal applied, and less than 1.5 volts when released. If voltage is within specification, check for intermittent fault in wiring harness. If voltage is not within specification, check and repair circuit between brakelight switch and ECM. See WIRING DIAGRAMS . If circuit is okay, replace ECM and retest.
  3. Connect scan tool to DLC3. See Figure. Turn the ignition to the ON position. Turn scan tool on. Read STP signal while applying and releasing brake pedal. Ensure signal cycles from ON (pedal applied) to OFF (pedal released). If signal cycles, check for intermittent fault in wiring harness. If signal does not cycle, check and repair circuit between brakelight switch and ECM. See WIRING DIAGRAMS . If circuit is okay, replace ECM and retest. See appropriate REMOVAL, OVERHAUL & INSTALLATION article in ENGINE PERFORMANCE.
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