Diagnostic Instructions
Circuit/System Description
The control module enables the appropriate fuel injector pulse for each cylinder. The ignition voltage is supplied directly to the fuel injectors. The control module 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 too low will affect the 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 customers concern. A fuel injector condition may only be apparent at a certain temperature, or under certain conditions. |
| • | If the condition is intermittent, move the related harnesses and connectors, with the engine operating, while monitoring the circuit status for the component with a scan tool. The circuit status parameter changes from OK or Indeterminate to Fault
if there is a condition with the circuit or a connection. |
Reference Information
Schematic Reference
Engine Controls Schematics
Electrical Information Reference
Component Testing
Verify the resistance of each fuel injector with one of the following methods:
| • | If the engine coolant temperature (ECT) sensor is between 10-32°C (50-90°F), the resistance of each fuel injector should be 11-14 Ω. |
| ⇒ | If the resistance of any fuel injector is not 11-14 Ω, replace the fuel injector. |
| • | If the ECT sensor is not between 10-32°C (50-90°F), measure and record the resistance of each fuel injector with a DMM. Subtract the lowest resistance value from the highest resistance value. The difference between the lowest
value and the highest value should be equal to or less than 3 Ω. |
| ⇒ | If the difference is more than 3 Ω, add all of the fuel injector resistance values to obtain a total resistance value. Divide the total resistance value by the number of fuel injectors to obtain an average resistance value. Subtract the
lowest, and the highest, individual fuel injector resistance values from the average resistance value. Replace the fuel injector that displays the greatest resistance difference above or below the average. |
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic procedure.
Fuel Injector Balance Test with Special Tool
