1990 Mitsubishi Precis Base, AutomaticFACTORY OEM SERVICE PROCEDURE

Sensor Operating Range Charts

NOTE: For connector and terminal identification see WIRING DIAGRAMS article.
AIRFLOW METER VOLTAGE TEST (1)

Condition Volts
700-3000 RPM 2.7-3.2
(1) Measure voltage between terminals No. 3 and 6 of airflow sensor connector.
BAROMETRIC PRESSURE SENSOR VOLTAGE TEST (1)

psi (kg/cm2 ) Volts
2.9 (20) 0.79
6.9 (49) 1.84
15 (103) 4.0
(1) Measure voltage between terminals No. 5 and 6 of barometric pressure sensor connector.
COOLANT TEMPERATURE SENSOR RESISTANCE TEST (1)

Temperature °F (°C) Ohms
32 (0) 5900
68 (20) 2500
104 (40) 1100
176 (80) 300
(1) Measure resistance across disconnected sensor terminals.
INTAKE AIR TEMP SENSOR RESISTANCE (1)

Temperature °F (°C) Ohms
32 (0) 6600-5400
68 (20) 2970-2300
176 (80) 310-430
(1) Measure resistance between terminals No. 4 and 6 of airflow sensor connector.
MOTOR POSITION SENSOR RESISTANCE TEST (1)

Condition Ohms
Connector Unplugged 4000-6000
Apply 6 volts (2) Resistance Changes Smoothly
(1) Measure resistance between terminals No. 2 and 3 of motor position sensor connector.
(2) Apply 6 volts between terminals No. 1 and 2. Check resistance between terminals No. 3 and 5.
OXYGEN SENSOR VOLTAGE TEST (1)(2)

Condition Volts
Lean 0.1
Rich 1.0
(1) Measure between sensor terminal No. 1 and ground or between terminals No. 1 and 2.
(2) Test at normal operating temperature.
THROTTLE POSITION SENSOR (TPS) RESISTANCE TEST

Position Terminal (1) (Ground-Output) Ohms
Closed 1-3 3500-6500
Open 1-2 500-(3500-6500)
(1) Measure across TPS terminals with connector removed.
VEHICLE SPEED SENSOR VOLTAGE TEST (1)(2)

Reed Switch Volts
On 1 or Less
Off 5
(1) Measure voltage at back of speedometer. See WIRING DIAGRAMS article.
(2) Roll vehicle to cycle reed switch on and off.
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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.