ECT Outside 10-35 Degrees C (50-95 Degrees F)

CIRCUIT DESCRIPTION

Schematic:

The injector coil test is performed to diagnose a faulty fuel injector. The injector coil lest makes use of the J 39021 Fuel Injector Tester. The tester is used to supply current to each fuel injector. This allows injector resistance measurement by using a digital multimeter (DMM) to measure voltage drop.

DIAGNOSTIC AIDS
Low voltage indicates a high resistance at an injectors coil.

TEST DESCRIPTION

Steps 1 - 4:

Voltage Chart:

The numbers below refer to the step numbers on the diagnostic table.

CAUTION: Refer to Shop Towel Fuel Leak Caution in Service Precautions.

2. The engine coolant temperature affects the ability of the fuel injector tester to detect a faulty fuel injector. If the engine coolant temperature is between 10°C-35°C (50°F-950 F), go to Fuel Injector Coil Test - Engine Coolant Temperature (ECT) Between 10-35 Degrees C (50-95 Degrees F). Component Tests and General Diagnostics

3. The first second of the voltage displayed by the DMM may be inaccurate due to the initial current surge, therefore, record the lowest voltage displayed by the DMM after the first second of the test. The voltage displayed by the DMM may increase throughout the test as the fuel injector windings warm and the resistance of the fuel injector windings changes. An erratic voltage reading (large fluctuations in voltage that do not stabilize) indicates an intermittent connection within the fuel injector. From the voltages recorded, identify the highest voltage, excluding any voltages above 9.5 volts. Subtract each voltage that is not above 9.5 volts from the highest voltage. Record each subtracted value (refer to the Example). The subtracted value for any fuel injector must not exceed 0.6 volt. A fuel injector with a subtracted value that is greater than 0.7 volt is considered faulty and must be replaced. A fuel injector with a recorded voltage above 9.5 volts is also considered faulty and must be replaced.