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Home >> Toyota >> 1997 >> Avalon XLS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Tests W/Codes >> Circuit Tests >> DTC P0450: EVAP Pressure Sensor Malfunction >> Diagnosis & Repair

Diagnosis & Repair

  1. Access ECM behind glove box. Turn ignition on. Backprobing ECM connector, measure voltage between terminals No. 1 (Blue/Red wire) and No. 22 (Brown wire) at ECM E7 connector. See Figure. If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, replace ECM and retest.
  2. Backprobing ECM connector, measure voltage between terminal No. 13 (Pink wire) at ECM E6 connector and No. 22 (Brown wire) at ECM E7 connector. Disconnect vacuum hose from vapor pressure sensor. Sensor is mounted on firewall, near brake booster. Apply vacuum or pressure to sensor as specified. Voltage reading should be as follows:
    • 2.9-3.7 volts with no vacuum applied.
    • 4.2-4.8 volts with .22 psi (1.5 kPa) applied.
    • 1.3-2.1 volts with .59 in. Hg (2.0 kPa) vacuum applied.

    If voltage is as specified, replace ECM and retest. If voltage is not as specified, go to next step.

  3. Check for an open or short in wiring harness between vapor pressure sensor and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair wiring as necessary. If wiring is okay, replace vapor pressure sensor.
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