1991 Plymouth Laser Base, StandardFACTORY OEM SERVICE PROCEDURE

Engine Controls - Sensor Operating Range Charts: Introduction

NOTE: This article is only to be used for Laser and Talon models. When testing sensors on other models, see appropriate G - TESTS W/ CODES article.

Sensor operating range information can help determine if a sensor is out of calibration. An out-of-calibration sensor may not set a trouble code, but it may cause driveability problems.

NOTE: Unless stated otherwise in test procedure, perform all voltage tests using a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance.
AIRFLOW SENSOR RESISTANCE (1)

Application Terminals No. Ohms
1.8L & 2.0L Non-Turbo 4 & 6 (2) *
2.0L Turbo 6 & 8 (2) *
(1) For testing procedure, see appropriate I - SYS/COMP TESTS article.
(2) Resistance should be approximately 6000 ohms at 32°F (0°C), 2700 ohms at 68°F (20°C) and 400 ohms at 176°F (80°C).
COOLANT TEMPERATURE SENSOR RESISTANCE (1)

Temperature °F (°C) Ohms
32 (0) 6000
68 (20) 2700
104 (40) 2500
176 (80) 400
(1) For testing procedure, see appropriate I - SYS/COMP TESTS article.
EGR TEMPERATURE SENSOR RESISTANCE (1)

Temperature °F (°C) Ohms
122 (50) 6000-8300
212 (100) 1100-1400
(1) For testing procedure, see appropriate I - SYS/COMP TESTS article.
IDLE SPEED MOTOR POSITION SENSOR RESISTANCE (1.8L) (1)

Terminals No. Ohms
2 & 3 4000-6000
3 & 5 (2) 4000-6000
(1) For testing procedure, see appropriate I - SYS/COMP TESTS article.
(2) With idle speed control plunger activated.
OXYGEN SENSOR VOLTAGE (1)

Application Volts
1.8L (2) .6-1.0
(1) For testing procedure, see appropriate I - SYS/COMP TESTS article.
(2) Warm engine until coolant temperature reaches 185-205°F (85-96°C). Measure voltage with engine running at more than 1300 RPM.
OXYGEN SENSOR RESISTANCE (2.0L & 2.0L TURBO) (1)

Terminals No. Ohms
3 & 4 (2) 12
3 & 4 (3) 30 or More
(1) Oxygen sensor can also be tested by measuring oxygen sensor output voltage. For testing procedure, see appropriate I - SYS/COMP TESTS article.
(2) With an oxygen sensor temperature of 68°F (20°C).
(3) With an oxygen sensor temperature of 752°F (400°C).
THROTTLE POSITION SENSOR RESISTANCE (1)

Terminals No. Ohms
1 & 4 3500-6500
2 & 4 3500-6500
(1) Operate throttle valve slowly from idle position to full open position. Check if resistance changes smoothly in proportion to throttle valve opening angle.
VEHICLE SPEED SENSOR RESISTANCE (1)

Application Ohms
All Models (2) *
(1) For testing procedure, see appropriate I - SYS/COMP TESTS article.
(2) Connect ohmmeter across reed switch terminals and rotate speedometer cable. Ohmmeter reading should fluctuate between continuity and no continuity.
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  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
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