GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2002 🢒 Sonoma Pickup - 2WD 🢒 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 a short to ground between the multi-way connector and the fuel injectors.

    4.

  4. This step tests for an open or high resistance between the multi-way connector and the fuel injectors.

Step

Action

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 ECM 1 fuse.

Is the ECM 1 fuse open?

Go to Step 4

Go to Step 6

4

  1. Turn OFF the ignition.
  2. Disconnect the multi-way harness connector of the fuel injectors.
  3. Probe the ignition 1 voltage supply circuit of the fuel injector, fuse side, with a test lamp connected to B+.

Does the test lamp illuminate?

Go to Step 9

Go to Step 5

5

Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

Go to Step 13

Go to Step 8

6

  1. Turn OFF the ignition.
  2. Disconnect the multi-way harness connector of the fuel injectors.
  3. Probe the ignition 1 voltage supply circuit of the fuel injector, fuse side, with a test lamp connected to a good ground.
  4. Crank the engine.

Does the test lamp illuminate while cranking the engine?

Go to Step 7

Go to Step 10

7

Test for continuity between the ignition 1 voltage supply terminal and a fuel injector terminal, at the multi-way harness connector, fuel injector side. Refer to Testing for Continuity in Wiring Systems.

Does the DMM display OL?

Go to Step 11

Go to Step 12

8

Test the ignition 1 voltage supply circuit of the fuel injector, between the multi-way harness connector and 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 14

Go to Intermittent Conditions

9

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

Did you complete the repair?

Go to Step 14

--

10

Repair the open in the ignition 1 voltage supply circuit of the fuel injector. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 14

--

11

Repair the ignition 1 voltage supply circuit of the fuel injectors for an open or high resistance, between the multi-way connector and the splice. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 14

--

12

Repair the poor connection at the multi-way harness connector. Refer to Connector Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 14

--

13

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

Did you complete the repair?

Go to Step 14

--

14

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3