Diagnostic Aids

WARNING: This page is about a different car, the 2004 GMC Envoy XUV, 2004 GMC Envoy XL, 2004 Chevrolet TrailBlazer, and 2004 Buick Rainier. However, it is still accessible from the selected car via links, so may be relevant.

The use of Dielectric compound GM P/N 12377900 (Canadian P/N 10953529) in the fuel injector electrical connector may eliminate a corrosion condition.
Monitoring the misfire current counters, or misfire graph, may help 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 fuel injector coil test does not isolate the condition perform the fuel injector balance test. Refer to Fuel Injector Balance Test with Special Tool or Fuel Injector Balance Test with Tech 2 .

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	Measure the resistance of each fuel injector with a DMM. 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	Measure the resistance of each fuel injector with a DMM. Refer to Testing for Continuity in Wiring Systems. Record each fuel injector value. 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	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 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