GM Service Manual Online
For 1990-2009 cars only

Refer to

Fuel Injectors


Object Number: 378479  Size: FS
Cell 10: Underhood Accessory Wiring Junction Block
Engine Data Sensors
Fuel Pump and Fuel Level Sensors
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
Engine Controls Components

Circuit Description

The powertrain control module (PCM) controls each fuel injector separately through a ground driver circuit located within the PCM. The PCM monitors the driver circuit and has the ability to detect an electrical malfunction. If the PCM detect an electrical malfunction in the fuel injector circuit for cylinder #4, DTC P0204 is set.

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

    • The PCM detects an electrical malfunction on the injector circuit for engine cylinder #4.
    • The condition is present for at least 30 seconds.

Action Taken When the DTC Sets

    • The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has run and failed.
    • If the electrical malfunction could lead to possible catalyst damage, the PCM immediately flashes the MIL while the fault remains at catalyst damaging levels.
    • The PCM disables TCC operation.
    • The PCM stores the conditions which were present when the DTC set as Freeze Frame and Fail Records data.

Conditions for Clearing the MIL/DTC

    • The PCM turns the MIL off during the third consecutive trip in which the diagnostic has run and passed.
    • The history DTC clears after 40 consecutive warm-up cycles have occurred without a malfunction.
    • The DTC may be cleared by using the scan tool Clear Info function or by disconnecting the PCM battery feed.

Diagnostic Aids

The misfire history counter may be useful in determining which injector circuit is malfunctioning. If DTC P0300 is set, look at the Misfire Hist # display for each cylinder. The largest value stored in the misfire history counters indicates the location of the malfunctioning injector circuit or injector.

Inspect for the following conditions:

    • A faulty connection at the PCM or the fuel injector. Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connections.
        
    • Inspect the wiring harness for damage.
        

Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.

Test Description

The number(s) below refer to the step number(s) on the Diagnostic Table.

  1. Checks for malfunctioning fuel injector control circuit or ignition feed wiring.

  2. Checks for a malfunction in the fuel injector ignition feed circuit.

  3. Checks for a short to ground in the injector control circuit.

  4. Checks for an open in the fuel injector control circuit.

  5. This vehicle is equipped with a powertrain control module (PCM) which utilizes an electrically erasable programmable read-only memory (EEPROM). When the PCM is replaced, the new PCM must be programmed.

DTC P0204 - Cylinder #4 Fuel Injector Control Circuit

Step

Action

Value(s)

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

With the engine idling, use a scan tool in order to monitor the Specific DTC info for DTC P0204.

Does the scan tool indicate DTC P0204 Failed This Ignition?

--

Go to Step 4

Go to Step 3

3

  1. Turn on the ignition switch.
  2. Review and record the scan tool Fail Records data.
  3. Operate the vehicle within the Fail Records conditions.
  4. Use the scan tool in order to monitor the Specific DTC info for DTC P0204.

Does the scan tool indicate DTC P0204 Failed This Ign?

--

Go to Step 4

Go to Diagnostic Aids

4

  1. Turn off the ignition switch.
  2. Disconnect the PCM.
  3. Turn on the ignition switch.
  4. Use a digital multimeter in order to measure the voltage between the cylinder #4 fuel injector control circuit and ground at the PCM connector.

Is the voltage near the specified value?

B+

Go to Step  5

Go to Step  9

5

Test the fuel injectors. Refer to Fuel Injector Solenoid Coil Test - Engine Coolant Temperature Between 10-35 Degrees C (50-95 Degrees F) or Fuel Injector Solenoid Coil Test - Engine Coolant Temperature Outside 10-35 Degrees C (50-95 Degrees F) .

Are the fuel injectors OK?

--

Go to Step  6

Go to Step  17

6

  1. Leave the PCM disconnected.
  2. Turn off the ignition switch.
  3. Disconnect the #4 fuel injector.
  4. Turn on the ignition switch.
  5. Measure the voltage between the cylinder #4 fuel injector control circuit and ground at the PCM connector.

Is the voltage near the specified value?

0 V

Go to Step 7

Go to Step 16

7

  1. Test for the following conditions:
  2. • The ignition feed circuit in the wire harness between the fuse and the cylinder #4 fuel injector for an intermittent open.
    • The cylinder #4 fuel injector control circuit between the PCM and the injector for an intermittent open or short to ground.
  3. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a problem found?

--

Go to Step  19

Go to Step  8

8

  1. Inspect for faulty terminal connections at the #4 fuel injector connector.
  2. Inspect the #4 fuel injector control circuit for faulty terminal connections at the PCM connector.
  3. If a problem is found, repair as necessary. Refer to Connector Repairs in Wiring Systems.

Was a problem found?

--

Go to Step  19

Go to Step  18

9

  1. Leave the PCM disconnected.
  2. Turn off the ignition switch.
  3. Disconnect the #4 fuel injector connector.
  4. Turn on the ignition switch.
  5. Measure the voltage between the ignition feed circuit and ground at the #4 fuel injector connector.

Is the voltage near the specified value?

B+

Go to Step 10

Go to Step 14

10

  1. Leave the PCM disconnected.
  2. Use a test lamp connected to B+ in order to probe the #4 fuel injector control circuit at the harness connector.

Does the test lamp illuminate?

--

Go to Step  15

Go to Step  11

11

  1. Leave the PCM disconnected.
  2. Turn off the ignition switch.
  3. Install a fused jumper between the #4 fuel injector control circuit and the ignition feed circuit at the injector harness connector.
  4. Turn on the ignition switch.
  5. Use a test lamp connected to ground in order to probe the #4 fuel injector control circuit at the PCM connector.

Does the test lamp illuminate?

--

Go to Step  12

Go to Step  13

12

  1. Inspect for faulty terminal connections at the #4 fuel injector connector.
  2. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a problem found?

--

Go to Step  19

Go to Step  17

13

Locate and repair anopen in the #4 fuel injector control circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step  19

--

14

Locate and repair an open or a short to ground in the #4 fuel injector ignition feed circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step  19

--

15

Locate and repair a short to ground in the #4 fuel injector control circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step  19

--

16

Locate and repair a short to voltage in the #4 fuel injector control circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

0v

Go to Step 19

--

17

Replace the malfunctioning fuel injector(s). Refer to Fuel Injection Fuel Rail Assembly Replacement .

Did you complete the repair?

--

Go to Step  19

--

18

Important:: The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming .

Replace the PCM.

Did you complete the repair?

--

Go to Step  19

--

19

  1. Review and record the scan tool Fail Records data.
  2. Clear any DTCs.
  3. Operate the vehicle within the Fail Records conditions.
  4. Use the scan tool in order to monitor the Specific DTC info for DTC P0204.

Does the scan tool indicate DTC P0204 Failed This Ign?

--

Go to Step 2

System OK