1996 Lexus SC 400FACTORY OEM SERVICE PROCEDURE

Vapor Pressure Sensor

  1. Turn ignition off. Access ECM behind glove box. Go to step 3)
  2. Backprobing ECM harness connector, measure voltage between terminals No. 18 (Pink/Green wire) at ECM E11 connector and No. 22 (Brown wire) at ECM E13 connector. Go to next step.
  3. Disconnect vacuum hose from vapor pressure sensor. Sensor is located in left side of engine compartment, near shock tower. Voltage reading should be as follows:
    • 3.0-3.6 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) applied.
  4. If voltage is not as specified, check for an open or short in wiring harness between vapor pressure sensor and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, replace vapor pressure sensor.
Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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