Diagnostic Aids

WARNING: This page is about a different car, the 2004 GMC Sierra and 2004 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.

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 customer's concern. A fuel injector condition may only be apparent at a certain temperature, or under certain conditions.

Fuel Injector Coil Test

Step	Action	Values	Yes	No
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End 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 ECT Sensor parameter with a scan tool. Is the ECT Sensor parameter within the specified range?	10-32° C (50-90° F)	Go to Step 3	Go to Step 4
3	Disconnect the multi-way harness connector of the fuel injectors. Measure the resistance of each fuel injector between the ignition 1 circuit and the fuel injector control circuit, at the multi-way connector with a DMM. Refer to Testing for Continuity in Wiring Systems. Is the resistance within the specified range for each injector?	11-14 ohm	Go to Fuel Injector Balance Test with Special Tool or Fuel Injector Balance Test with Tech 2	Go to Step 6
4	Disconnect the multi-way harness connector of the fuel injectors. Measure the resistance of each fuel injector between the ignition 1 voltage circuit and the fuel injector control circuit, at the multi-way connector with a DMM. Refer to Testing for Continuity in Wiring Systems. Record each fuel injector resistance value. Subtract the lowest resistance value from the highest resistance value. Is the difference equal to, or less than, the specified value?	3 ohm	Go to Fuel Injector Balance Test with Special Tool or Fuel Injector Balance Test with Tech 2	Go to Step 5
5	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 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 with resistance that is out of the specified range. Refer to Fuel Injector Replacement . Did you complete the replacement?	11-14 ohm	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