GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Aveo 🢒 Engine 🢒 Engine Controls - 1.5L 🢒 DTC P0203

Circuit Description

The engine control module (ECM) has 4 individual injector driver circuits, each of which controls an injector. When a driver circuit is grounded by the ECM, the injector is activated. The ECM monitors the current in each driver circuit. The ECM measures a voltage drop through a fixed resistor and controls it. The voltage on each driver is monitored to detect a fault. If the voltage is not what the ECM expects to monitor on the circuit, a DTC is set. This DTC detects a short to ground and/or an open circuit and short to battery conditions for low-side drive injector outputs.

Conditions for Setting the DTC
    • Monitor the fault feedback signal from FETS.
    • The engine is in run mode.
    • Battery voltage is greater than 9 volts.
    • The engine speed is greater than 700 RPM.
    • The fault is present for more than 5 seconds.

Action Taken When the DTC Sets
    • The ECM will illuminate the malfunction indicator lamp (MIL) the first time the fault is detected.
    • The ECM will store conditions which were present when the DTC was set as Freeze Frame and in the Failure Records data.

Conditions for Clearing the MIL/DTC
    • The ECM will turn OFF the MIL on the third consecutive trip cycle in which the diagnostic has been run and the fault is no longer present.
    • A history DTC will clear after 40 consecutive warm-up cycles without a fault.
    • A DTC can be cleared by using the scan tool Clear Info function.
    • Disconnect the ECM battery feed for more than 10 seconds.

Diagnostic Aids

An injector 3 driver circuit that is open or shorted to voltage will cause a DTC P0203 to set. It will also cause a misfire due to an inoperative injector. A misfire DTC should also be set indicating which injector is inoperative.

Long-term and short-term fuel trims that are excessively high or low are a good indication that an injector is malfunctioning. Refer to Fuel Injector Balance Test with Special Tool to inspect for malfunctioning injectors.

The injector resistance tested at the ECM connection is slightly more than if tested directly at the injector because it includes resistance of the harness wires. The normal value is about 13.5 ohms.

Test Description

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

  1. The On-Board Diagnostic 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 malfunction occurred. The information is then stored on the scan tool for later reference.

    2.

  2. This step determines if DTC P0203 is the result of a hard failure or an intermittent condition.

    3.

  3. This step tests the wiring harness and ECM control of the injectors using a test light.

    4.

  4. This step determines if the circuitry is shorted to voltage or the ECM is faulty.

    5.

  5. The replacement ECM must be reprogrammed. Refer to the latest Techline procedure for ECM reprogramming.

Step

Action

Yes

No

1

Perform an On-Board Diagnostic System Check.

Was the check performed?

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

Will the engine start?

Go to Step 3

Go to Engine Cranks but Does Not Run

3

  1. Install a scan tool to the data link connector (DLC).
  2. Turn the ignition ON, with the engine OFF.
  3. Clear the DTCs using a scan tool.
  4. Start the engine and idle for 1 minute.

Does DTC P0203 reset?

Go to Step 5

Go to Step 4

4
  1. Turn the ignition ON, with the engine OFF.
  2. Review the Freeze Frame data and note the parameters.
  3. Operate the vehicle within the Freeze Frame conditions as noted.

Does DTC P0203 reset?

Go to Step 5

Go to Diagnostic Aids

5

  1. Turn the ignition OFF.
  2. Disconnect the engine control module (ECM) connector for injector 3.
  3. Turn the ignition ON, with the engine OFF.
  4. With a test light connected to ground, probe the driver circuit, terminal A8.

Does the test light illuminate?

Go to Step 7

Go to Step 8

6

Repair the short to ground or open in the injector driver circuit.

Did you complete the repair?

Go to Step 10

--

7

  1. Disconnect the injector 3 wiring connection.
  2. With a test light connected to ground, probe the driver circuit, terminal 2.

Does the test light illuminate?

Go to Step 8

Go to Step 9

8

Repair the short to voltage in the injector driver circuit.

Did you complete the repair?

Go to Step 10

--

9

  1. Turn the ignition OFF.
  2. Replace the ECM. Refer to Engine Control Module Replacement .

Did you complete the replacement?

Go to Step 10

--

10
  1. Using the scan tool, clear the DTCs.
  2. Start the engine and idle at normal operating temperature.
  3. Operate the vehicle within the Conditions for Setting the DTC as specified in the supporting text.

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

Go to Step 10

Go to Step 2

11

Are any DTCs displayed that have not been diagnosed?

Go to applicable DTC table

System OK