GM Service Manual Online
For 1990-2009 cars only

Refer to

Fuel Controls


Object Number: 28049  Size: FS
Engine Controls Components
Powertrain Control Module (PCM) General Description
Engine Data Sensors
Ignition Controls
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The Powertrain Control Module (PCM) has four fuel injector driver circuits, each of which controls a fuel injector. The PCM monitors the current in each driver circuit and is able to control the driver circuit. The current through each driver can rise to a peak of 2 amps in order to quickly open the fuel injectors. The current can reduce to 1/2 amp to hold the fuel injectors open. This is called peak and hold. If the current cannot reach a 2-amp peak, a DTC is set. This DTC is also set if a fuel injector driver is shorted to voltage.

Conditions for Setting the DTC

    • Injector current is less than 4 amps.
    • Battery voltage is more than 9 volts.
    • Above conditions met for 10 seconds.

Action Taken When the DTC Sets

    • The malfunction indicator lamp (MIL) illuminates.
    • The PCM records the operating conditions at the time when the diagnostic fails. This information stores in the Freeze Frame and Failure Records buffers.
    • A history DTC stores.
    • The coolant fan turns ON.

Conditions for Clearing the MIL/DTC

    • The MIL will turn OFF after three consecutive ignition cycles in which the diagnostic runs without a fault.
    • A history DTC will clear after 40 consecutive warm-up cycles without a fault.
    • The MIL/DTCs can be cleared by using the scan tool.

Diagnostic Aids

An injector driver circuit that is open or shorted to voltage will cause a DTC P0200 to set and will also cause a misfire due to an inoperative injector. A misfire DTC should also be set indicating which cylinder is inoperative.

Long term and short term fuel trims that are excessively high or low are a good indication that an injector is faulty. Use Fuel Injector Solenoid Coil Test to check for faulty injectors.

Test Description

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

  1. The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored on the scan tool for later reference.

  2. This step determines if DTC P0200 is the result of a hard failure or an intermittent condition.

  3. Test the harness wiring and for PCM control of the injectors using test light J 34780-2. If the tests light blinks, the PCM and wiring to the injectors are OK. Fuel Injector Solenoid Coil Test will check if injectors are faulty.

  4. Whether the test light was ON steady or OFF while cranking the engine narrows the possible faults down to just a few.

  5. Because the test light was ON steady, voltage to the injector is OK, but the driver circuit is grounded at all times. This step determines if the circuitry is shorted to ground or the PCM is faulty.

  6. Replacement PCM's must be reprogrammed. Refer to the latest Techline information for programming procedures.

  7. Determines if voltage is available to the injector. Voltage is supplied through the fuel pump relay so the engine must be cranked to see voltage at the injector.

  8. This step determines if the driver circuit is open or shorted to voltage or if the PCM is faulty.

  9. Since voltage is supplied to the injector on a single circuit before the injector harness, the fault could only be a poor connection or open in the injector harness. An open before the harness would result in a Cranks But Won't Run complaint.

  10. Check the injector electrical connector, the injector harness connector and the PCM for poor connections or corroded terminals.

DTC P0200-Injector Control Circuit

Step

Action

Value(s)

Yes

No

1

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

Will the engine start?

--

Go to Step 3

Go to Engine Cranks but Does Not Run

3

  1. Install a scan tool, clear the DTC.
  2. Idle the engine for one minute.

Does DTC P0200 reset?

--

Go to Step 5

Go to Step 4

4

  1. Turn the ignition switch ON, with engine OFF.
  2. Review the Freeze Frame data and note the parameters.
  3. Operate the vehicle within the Freeze Frame conditions and Conditions For Setting The DTC as noted.

Does P0200 Reset?

--

Go to Step 5

Go to Step 16

5

  1. With the engine OFF.
  2. Remove the air cleaner outlet resonator for injector access. Refer to Air Cleaner Resonator .
  3. Disconnect all 4 injectors connectors from the injectors.
  4. Install an injector test light on injector 1.
  5. Crank the engine and note the injector test light.
  6. Remove the injector test light and install the injector test light on the remaining injectors connectors.
  7. Crank the engine and note the injector test light on the remaining injectors connectors.

Does the injector test light blink on all test?

--

Go to Fuel Injector Solenoid Coil Test

Go to Step 6

6

Note whether the injector test light was OFF or ON steady in step 5 for the injector connector that did not blink.

Was the injector test light ON steady while cranking the engine?

--

Go to Step 7

Go to Step 10

7

  1. Disconnect the PCM connector for the affected injector.
  2. With a test light connected to B+, probe the affected injector driver circuits.

Does the injector test light illuminate?

--

Go to Step 8

Go to Step 9

8

Check for a short to ground in the injector driver circuit and repair as necessary.

Was a repair necessary?

--

Go to Step 16

Go to Step 9

9

Replace the PCM.

Is the action complete?

--

Go to Step 16

--

10

  1. With a test light connected to ground, probe the ignition feed circuit of the affected connector.
  2. Crank the engine.

Does the test light illuminate while cranking?

--

Go to Step 11

Go to Step 12

11

  1. With a test light connected to ground, probe the injector driver circuit of the affected connector.
  2. Crank the engine.

Is the test light OFF while cranking?

--

Go to Step 13

Go to Step 14

12

Repair the open in the ignition feed circuit in the injector harness.

Is the action complete?

--

Go to Step 16

--

13

Check the injector driver circuit for an open or faulty connection.

Was a problem found?

--

Go to Step 15

Go to Step 9

14

Repair the short to voltage in the injector driver circuit.

Is the action complete?

--

Go to Step 16

--

15

Repair the open or faulty connection in the injector driver circuit.

Is the action complete?

--

Go to Step 16

--

16

  1. Using the scan tool, clear the DTC's.
  2. Start the engine and idle at normal operating temperature.
  3. Operate the vehicle within the conditions for setting this DTC as specified in the supporting text.

Does the scan tool indicate that this diagnostic has ran and passed?

--

Go to Step 17

Go to Step 2

17

Check if any additional DTC's are set.

Are any DTC's displayed that have not been diagnosed?

--

Go to applicable DTC table

System OK