GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Saturn 🢒 2003 🢒 L300/LW300 🢒 Engine 🢒 Engine Controls - 3.0L (L81) 🢒 Fuel Injector Solenoid Coil Test

Circuit Description

The engine control module (ECM) enables the appropriate fuel injector on the intake stroke for each cylinder. Ignition voltage is supplied directly to the fuel injectors. The ECM controls each fuel injector by grounding the control circuit via a solid state device called a driver. A fuel injector coil winding resistance that is too high, or low, will affect engine driveability. A fuel injector control circuit DTC may not set, but a misfire may be apparent. The fuel injector coil windings are affected by temperature. The resistance of the fuel injector coil windings will increase as the temperature of the fuel injector increases.

Diagnostic Aids
    • Monitoring the misfire current counters, or misfire graph, may help to isolate the fuel injector that is causing the condition.
    • Operating the vehicle over a wide temperature range may help isolate the fuel injector that is causing the condition.
    • Perform the fuel injector coil test within the conditions of the customer's concern. A fuel injector condition may only be apparent at a certain temperature, or under certain conditions.
    • If the fuel injector coil test does not isolate the condition perform the fuel injector balance test. Refer to Fuel Injector Balance Test with Special Tool .

Test Description

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

  1. This step tests each fuel injector resistance within a specific temperature range.

    2.

  2. This step determines if all of the fuel injectors are within 3 ohms of each other. If the highest resistance value is within 3 ohms of the lowest resistance value, then all of the fuel injector coil windings are OK.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views

1

Did you perform the Diagnostic System Check-Engine Controls?

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Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

Observe the engine coolant temperature (ECT) with a scan tool.

Is the ECT parameter above the specified value?

20°C (68°F)

Go to Step 3

Go to Step 4

3

  1. Disconnect the fuel injector multi-way harness connector.
  2. Measure the resistance of each fuel injector between the ignition feed circuit and the fuel injector control circuit, at the multi-way connector, with the DMM. Refer to Testing for Continuity in Wiring Systems.

Do any of the fuel injectors display a resistance outside the specified range?

13-15.5 ohms

Go to Step 6

Go to Diagnostic Aids

4

  1. Disconnect the fuel injector multi-way harness connector.
  2. Measure the resistance of each fuel injector between the ignition feed circuit and the fuel injector control circuit, at the multi-way connector, with the DMM. Refer to Testing for Continuity in Wiring Systems.
  3. Record each fuel injector value.
  4. Subtract the lowest resistance value from the highest resistance value.

Is the difference equal to, or less than, the specified value?

3 ohms

Go to Fuel Injector Balance Test with Special Tool

Go to Step 5

5

  1. Add all of the fuel injector resistance values to obtain a total resistance value.
  2. Divide the total resistance value by the number of fuel injectors, to obtain an average resistance value.
  3. Subtract the lowest individual fuel injector resistance value from the average resistance value.
  4. Subtract the average resistance value from the highest individual fuel injector resistance value.
  5. Replace the fuel injector that displays the greatest resistance difference above or below the average. Refer to Fuel Injector Replacement and Fuel Injection Fuel Rail Assembly Replacement .

Did you complete the replacement?

--

Go to Step 7

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6

Replace the fuel injector or fuel injectors that are out of the specified range. Refer to Fuel Injector Replacement and Fuel Injection Fuel Rail Assembly Replacement .

Did you complete the replacement?

13-15.5 ohms

Go to Step 7

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7

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2