Fuel Injector Solenoid Coil Test

/ 9-5 (9650) / 2010 / 2. Engine / Engine management and fuel system, 4-cyl petrol / Fault diagnosis, fault symptoms / Fuel Injector Solenoid Coil Test

Diagnostic Instructions

•	Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

•	Review Strategy Based Diagnosis for an overview of the diagnostic approach.

•	Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Circuit/System Description

The engine control module (ECM) supplies a separate high voltage supply circuit and a high voltage control circuit for each fuel injector. The injector high voltage supply circuit and the high voltage control circuit are both controlled by the ECM. The ECM energizes each fuel injector by grounding the control circuit. The ECM controls each fuel injector with 65 V. This is controlled by a boost capacitor in the ECM. During the 65 V boost phase, the capacitor is discharged through an injector, allowing for initial injector opening. The injector is then held open with 12 V. A fuel injector coil winding resistance that is too high or too low will affect the engine driveability. 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 Current Misfire Counters, or misfire graph, may help to isolate the fuel injector that is causing the condition.

•	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 Not Run to Fault if there is a condition with the circuit or a connection.

Reference Information

Schematic Reference

Engine Controls Schematics

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

Component Testing

Note
•	The resistance test must be performed at the fuel injector or mis-diagnosis will occur.
•	The DMM and test leads must be calibrated to 0 Ω in order to prevent misdiagnosis.

Verify the resistance of each Q17 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 Q17 fuel injector should be 1.25-1.75 Ω.

•	If not within the specified range, replace the Q17 fuel injector.

•	If the ECT sensor is not between 10-32°C (50-90°F), measure and record the resistance of each Q17 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 0.45 Ω.

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If the difference is more than 0.45 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 individual fuel injector resistance value from the average resistance value. Compute the difference between the highest individual fuel injector resistance value and the average resistance value. Replace the Q17 fuel injector that displays the greatest difference above or below the average.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Direct Fuel Injector Replacement

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