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Home >> Buick >> 2004 >> Century Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls 3.1L (Troubleshooting & Diagnosis) >> Engine Controls >> Fuel Injector Coil Test >> Test Description
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Test Description

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

  1. 3:  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.
  2. 4:  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.
  3. 5:  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.
Fuel Injector Coil Test

Step Action Values Yes No
Schematic Reference:  Engine Controls Schematics 
Connector End View Reference:  Engine Controls Component Views  or  Powertrain Control Module (PCM) Connector End Views 
1 Did you perform the Diagnostic System Check-Engine Controls? - 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 value within the specified range?		 10-32°C (50-90°F) Go to Step 3  Go to Step 4 
3 
  1. Disconnect the fuel injector multi-way harness connector.
  2. With a DMM, measure the resistance of each fuel injector between the ignition feed circuit and the fuel injector control circuit, at the multi-way connector. Refer to Testing for Continuity in Wiring Systems.
Do any of the fuel injectors display a resistance outside the specified range?		 11-14 Ω Go to Step 6  Go to Diagnostic Aids
4 
  1. Disconnect the fuel injector multi-way connector.
  2. With a DMM, measure the resistance of each fuel injector between the ignition feed circuit and the fuel injector control circuit, at the multi-way connector. 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 Ω Go to Fuel Injector Balance Test with Special Tool  or Fuel Injector Balance Test with Tech 2  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 and the highest individual fuel injector resistance values from the average resistance value.
  4. Replace the fuel injector that displays the greatest resistance difference, above or below the average. Refer to Fuel Injector Replacement .
Did you complete the replacement?		 - Go to Step 7  -
6 Replace the fuel injector or fuel injectors that are out of the specified range. Refer to Fuel Injector Replacement .
Did you complete the replacement?		 11-14 Ω Go to Step 7  -
7 Operate the system in order to verify the repair.
Did you correct the condition?		 - System OK Go to Step 2 
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