GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2002 🢒 Sunfire 🢒 Engine 🢒 Engine Electrical 🢒 Fuel Injector Circuit Diagnosis

Circuit Description

The powertrain control module (PCM) enables the appropriate fuel injector on the intake stroke for each cylinder. A voltage is supplied directly to the fuel injectors. The PCM controls each fuel injector by grounding the control circuit via a solid state device called a driver.

Diagnostic Aids
    •  Monitoring the fuel injector circuit status with a scan tool, while moving the fuel injector harness, may help isolate an intermittent condition.
    • Performing the Fuel Injector Coil test may help isolate an intermittent condition. Refer to Fuel Injector Solenoid Coil Test .
    • For an intermittent condition, refer to Intermittent Conditions .

Test Description

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

  1. This step tests for a short to ground on the ignition 1 voltage supply circuit of the fuel injector.

    2.

  2. This step tests for a short to a PCM ground on the ignition 1 voltage supply circuit of the fuel injector.

    3.

  3. This step tests for an open ignition 1 voltage supply circuit between the fuel pump relay and the fuel injectors.

    4.

  4. This step tests for high resistance between the fuel pump relay and the fuel injectors.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

1

Did you perform the Diagnostic System Check-Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

Are any fuel injector DTCs set?

--

Go to DTC P0201, P0202, P0203, or P0204

Go to Step 3

3

Inspect the fuel injector fuse.

Is the fuel injector fuse open?

--

Go to Step 4

Go to Step 6

4

  1. Turn OFF the ignition.
  2. Disconnect the harness connectors of the fuel injectors.
  3. Disconnect the harness connector of the fuel pump at the body pass through connector.
  4. Probe the ignition 1 voltage supply circuit of a fuel injector, fuse side, with a test lamp connected to B+.

Does the test lamp illuminate?

--

Go to Step 8

Go to Step 5

5

Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

--

Go to Step 11

Go to Diagnostic Aids

6

  1. Turn OFF the ignition.
  2. Disconnect the harness connector of a fuel injector.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the ignition 1 voltage supply circuit of the fuel injector, fuse side, with a test lamp connected to a good ground.
  5. Command the fuel pump ON with a scan tool.

Does the test lamp illuminate when the fuel pump is commanded ON?

--

Go to Step 7

Go to Step 9

7

  1. Disconnect the fuel pump relay.
  2. Test for continuity between the fuel pump relay load terminal and an ignition 1 voltage supply terminal of a fuel injector. Refer to Testing for Continuity in Wiring Systems.

Does the DMM display a resistance above the specified value?

5 ohms

Go to Step 10

Go to Intermittent Conditions

8

Test the ignition 1 voltage supply circuit of the fuel injectors for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 12

--

9

Repair the open in the ignition 1 voltage supply circuit of the fuel injectors. Refer to Circuit Testing in Wiring Systems.

Did you complete the repair?

--

Go to Step 12

--

10

Repair the high resistance in the ignition 1 voltage supply circuit of the fuel injectors. Refer to Circuit Testing in Wiring Systems.

Did you complete the repair?

--

Go to Step 12

--

11

Repair the short to a PCM ground in the ignition 1 voltage supply circuit of the fuel injectors. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 12

--

12

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 3