Circuit Description
The powertrain control module (PCM) enables the appropriate fuel injector on the intake stroke for each cylinder. Ignition voltage is supplied directly to the fuel injectors. The PCM 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 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 customers 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 or Fuel Injector Balance Test with Tech 2 . |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This step tests each fuel injector resistance within a specific temperature range. If any of the fuel injectors display a resistance outside of the specified value, replace the fuel injector.
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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.
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This step determines if the ignition 1 voltage circuit under the intake plenum is causing the concern.
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This step determines which fuel injector is faulty. After subtracting the highest and lowest resistance values from the average value, replace the fuel injector that has the greatest resistance difference from the average.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module Connector End Views | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
2 | Observe the engine coolant temperature (ECT) with a scan tool. Is the ECT value within the specified range? | 10-32°C (50-90°F) | Go to Step 3 | Go to Step 4 |
Do any of the fuel injectors display a resistance outside the specified range? | 11-14 ohms | Go to Step 5 | Go to Diagnostic Aids | |
Is the difference equal to, or less than, the specified value? | 3 ohms | Go to Fuel Injector Balance Test with Special Tool or Fuel Injector Balance Test with Tech 2 | Go to Step 8 | |
5 | Remove the upper intake manifold. Refer to Upper Intake Manifold Replacement in Engine Mechanical. Did you complete the action? | -- | Go to Step 6 | -- |
Measure the resistance of the ignition 1 voltage circuit between the multi-way connector and the affected fuel injector connector, with a DMM. Is the resistance more than the specified value? | 5 ohms | Go to Step 7 | Go to Step 9 | |
7 | Repair the open or high resistance in the ignition 1 voltage circuit. Did you complete the repair? | -- | Go to Step 11 | -- |
Did you complete the replacement? | -- | Go to Step 11 | -- | |
9 | Test for an intermittent and for a poor connection at the affected fuel injector. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 10 |
10 | Replace any fuel injectors that are out of the specified range. Refer to Fuel Injector Replacement . Did you complete the replacement? | 11-14 ohms | Go to Step 11 | -- |
11 | Operate the system in order to verify the repair. Did you correct the condition? | -- | System OK | Go to Step 2 |
