Fuel Injector Diagnosis — Special Tool
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.
The active fuel injector tester CH 47976 Active Fuel Injector Tester is used to test the fuel pump, fuel system leak down, and the fuel injectors. Following the user guide, and the on-screen prompts or selections, will indicate the steps required to perform each of the available tests. The tester will perform all of the tests automatically and display the results of the test. The results can also be downloaded for storage and printing.
Reference Information
Schematic Reference
Engine Controls Schematics
Connector End View Reference
Component Connector End Views
Electrical Information Reference
Special Tools
CH 47976 Active Fuel Injector Tester
For equivalent regional tools, refer to Special Tools .
Component Testing
Fuel Injector Coil Static Test
Verify the resistance of each fuel injector with one of the following methods:
| • | If the B34A Engine Coolant Temperature Sensor 1 is between 10-32°C (50-90°F), the resistance of each fuel injector should be 11-14 Ω. |
| ⇒ | If the injectors measure OK, perform the active fuel injector tester test procedure. |
| ⇒ | If not within the specified range, replace the fuel injector. |
| • | If the B34A Engine Coolant Temperature Sensor 1 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 two should be equal to or less than 3 Ω. |
| ⇒ | If the difference is equal to or less than 3 Ω, refer to active fuel injector tester test procedure for further diagnosis of the fuel injectors. |
| ⇒ | 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 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 fuel injector that displays the greatest difference above or below the average. |
Active Fuel Injector Tester Static Test Procedure
Note:
| • | DO NOT perform this test if the engine coolant temperature (ECT) is above 94°C (201°F). Irregular fuel pressure readings may result due to hot soak fuel boiling. |
| • | Verify that adequate fuel is in the fuel tank before proceeding with this diagnostic. |
- Turn OFF all accessories.
- Turn OFF the ignition.
- Install the active fuel injector tester. Refer to the active fuel injector tester user guide.
- Turn ON the active fuel injector tester and select the vehicle.
- Turn ON the ignition and perform the injector test.
| ⇒ | If the active fuel injector tester aborts testing due to fuel pressure or fuel leak down, refer to Fuel System Diagnosis . |
- View the test results.
| ⇒ | If any injector exceeds the recommended tolerance, replace the injector(s). |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
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