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Home >> Toyota >> 1998 >> Tercel Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Tests W/Codes >> Self-Diagnostic Tests >> DTC P0450: EVAP Pressure Sensor Fault Or DTC P0451: EVAP Pressure Sensor Range/Performance >> Diagnosis & Repair
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Diagnosis & Repair

  1. Access ECM behind glove box. Turn ignition on. Backprobing ECM connector, measure voltage between terminals No. 11 (Light Green/Red wire) and No. 9 (Brown wire) at ECM E6 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.
  2. Backprobe ECM connector. Measure voltage between terminals No. 12 (Yellow/Black wire) and No. 9 (Brown wire) at ECM E6 connector. Disconnect vacuum hose from vapor pressure sensor. Sensor is located in right rear of engine compartment. Connect a vacuum pump to sensor. If voltage is 3.0-3.6 volts without vacuum applied and 1.3-2.1 volts with .59 in. Hg (2 kPa) vacuum applied, replace ECM. If voltage is not as specified, go to next step.
  3. Check for open or short circuit in wiring harness between vapor pressure sensor and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair wiring as necessary. If wiring harness is okay, replace vapor pressure sensor.
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