GM Service Manual Online
For 1990-2009 cars only
Table 1: Example
Table 2: Engine Coolant Temperature Outside 10°C - 35°C (50°F - 95°F) Test Procedure

Object Number: 17707  Size: MF

Diagnostic Aids

Example

Highest Voltage Reading

Acceptable Subtracted Value Above/Below

10°C-35°C

(50°F-95°F)

7.1 Volts

0.6 Volts

Injector Number

Voltage

Subtracted Value

Pass/Fail

1

9.8

F

2

6.6

0.5

P

3

6.9

0.2

P

4

5.8

1.3

F

5

7.0

0.1

P

6

7.1

0.0

P

Test Description

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

Caution: Wrap a shop towel around the fuel pressure connection in order to reduce the risk of fire and personal injury. The towel will absorb any fuel leakage that occurs during the connection of the fuel pressure gage. Place the towel in an approved container when the connection of the fuel pressure gage is complete.

  1. The engine coolant temperature affects the ability of the fuel injector tester to detect a faulty fuel injector. If the engine coolant temperature is NOT outside 10°C-35°C (50°F-95°F), go to Fuel Injector Coil Test Procedure - Engine Coolant Temperature Between 10°C-35°C (50°F-95°F).

  2. The first second of the voltage displayed by the DMM may be inaccurate due to the initial current surge, therefore, record the lowest voltage displayed by the DMM after the first second of the test. The voltage displayed by the DMM may increase throughout the test as the fuel injector windings warm and the resistance of the fuel injector windings changes. An erratic voltage reading, large fluctuations in voltage that do not stabilize, indicates an intermittent connection within the fuel injector. From the voltages recorded, identify the highest voltage, excluding any voltages above 9.5 volts. Subtract each voltage that is not above 9.5 volts from the highest voltage. Record each subtracted value, refer to the Example. The subtracted value for any fuel injector must not exceed 0.6 volts. A fuel injector with a subtracted value that is more than 0.7 volts is considered faulty and must be replaced. A fuel injector with a recorded voltage above 9.5 volts is also considered faulty and must be replaced.

Engine Coolant Temperature Outside 10°C - 35°C (50°F - 95°F) Test Procedure

Step

Action

Values

Yes

No

1

Did you perform the Powertrain On Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

  1. Turn ON the ignition, with the engine OFF.
  2. With a scan tool, monitor the ECT parameter.

Does the temperature measure outside the specified value?

10°C-35°C (50°F-95°F)

Go to Step 3

Go to Fuel Injector Solenoid Coil Test - Engine Coolant Temperature Between 10-35 Degrees C (50-95 Degrees F)

3

Important: The Fuel system must not be pressurized.

  1. Relieve the fuel pressure. Refer to Fuel Pressure Relief .
  2. Disconnect the fuel injector connector.
  3. Install the J 39021 fuel injector coil/balance tester.
  4. Select the coil test 0.5 AMP position on the fuel injector tester.
  5. Connect the leads on the DMM to the fuel injector tester and select DC voltage tenths scale.
  6. Press the PUSH TO START TEST button on the fuel injector coil/balance tester.
  7. Record the lowest voltage after the first second of the test.
  8. Repeat for each injector.

Does any fuel injector have an erratic reading or a reading above the specified value?

9.5 V

Go to Step 5

Go to Step 4

4

  1. From the recorded readings, identify the highest voltage.
  2. Subtract all other voltage readings from the highest voltage recorded.

Does any subtracted value exceed the specified value?

0.6 V

Go to Step 5

Go to Fuel Injector Balance Test

5

Replace the faulty fuel injectors. Refer to Fuel Injector Replacement .

Is the action complete?

--

Go to Step 6

--

6

Does any driveabilty condition still exist?

--

Go to applicable Diagnostic

System OK