GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2005 🢒 Grand Am 🢒 Engine 🢒 Engine Electrical 🢒 Fuel Injector Circuit Diagnosis

Circuit Description

The control module enables the appropriate fuel injector pulse for each cylinder. Ignition voltage is supplied to the fuel injectors. The control module controls each fuel injector by grounding the control circuit via a solid state device called a driver.

Diagnostic Aids
    • 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 .

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

Connect End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

Is DTC P0201, P0202, P0203, or P0204 set?

--

Go to DTC P0201, P0202, P0203, or P0204

Go to Step 3

3
  1. Turn OFF the ignition.
  2. Remove the air cleaner outlet resonator. Refer to Air Cleaner Outlet Resonator Replacement .
  3. Disconnect the harness connector of a fuel injector.
  4. Turn ON the ignition, with the engine OFF.
  5. Probe the ignition 1 voltage circuit of a fuel injector, fuse side, with a test lamp that is connected to a good ground. Refer to Probing Electrical Connectors in Wiring Systems.

Does the test lamp illuminate?

--

Go to Step 4

Go to Step 10

4
  1. Remove the F/P INJR fuse.
  2. Measure the resistance from the F/P INJR fuse to the ignition 1 voltage circuit terminal of a fuel injector with a DMM. Refer to Circuit Testing in Wiring Systems.

Is the resistance more than the specified value?

5 ohms

Go to Step 11

Go to Step 5

5
  1. Connect the J 34730-405 Injector Test Lamp into each injector connector one at a time.
  2. Crank the engine.

Does the test lamp flash for each injector?

--

Go to Fuel Injector Solenoid Coil Test

Go to Step 6

6

Does the test lamp remain illuminated at all times for any injector circuit?

--

Go to Step 8

Go to Step 7

7

Test the control circuits of the fuel injectors for an open and for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 9

8

Test the control circuits 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 13

Go to Step 12

9

Test for an intermittent and for a poor connection at the powertrain control module (PCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 12

10

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

Did you complete the repair?

--

Go to Step 13

--

11

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

Did you complete the repair?

--

Go to Step 13

--

12

Replace the PCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 13

--

13

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2