Vacuum Sensor
- Ensure ignition is off. To check vacuum sensor supply voltage, disconnect electrical connector from vacuum sensor.
- Vacuum sensor is located on center of firewall.NOTE: Vacuum sensor has a vacuum hose connected to it and may be identified by wire colors. See appropriate wiring diagram in WIRING DIAGRAMS article in the ENGINE PERFORMANCE Section.
- Turn ignition on. Using voltmeter, measure voltage between terminals VCC and E2 of harness connector. See Fig 1. Voltage should be within specification. See VACUUM SENSOR SUPPLY VOLTAGE SPECIFICATIONS table.VACUUM SENSOR SUPPLY VOLTAGE SPECIFICATIONS
Application Voltage Tercel 4.00-6.00 - If supply voltage is not within specification, check wiring circuit. See appropriate wiring diagram in WIRING DIAGRAMS article in the ENGINE PERFORMANCE Section. If supply voltage is correct, turn ignition off and reinstall electrical connector on vacuum sensor.
- To check vacuum sensor output voltage, turn ignition on. Disconnect vacuum sensor vacuum hose from intake manifold. Connect voltmeter to terminals PIM and E2 of Electronic Control Unit (ECU). See Fig 2. See ECU LOCATION table.ECU LOCATION
Application Location Tercel Bottom Center Of Dash, In Front Of Console - Measure and record output voltage under ambient atmospheric pressure. Attach vacuum pump to vacuum sensor.
- Apply vacuum in specified increments and measure output voltage drop at each increment. See VACUUM SENSOR OUTPUT VOLTAGE DROP SPECIFICATIONS table. Replace vacuum sensor if output voltage drop is not within specification.
VACUUM SENSOR OUTPUT VOLTAGE DROP SPECIFICATIONS
| Applied Vacuum In. Hg | Output Voltage Drop |
|---|---|
| 3.94 | .3-.5 |
| 7.87 | .7-.9 |
| 11.81 | 1.1-1.3 |
| 15.75 | 1.5-1.7 |
| 19.69 | 1.9-2.1 |