GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2003 🢒 Express (CNG) 🢒 DTC 🢒 DTC P1209

Circuit Description

The fuel injector control module (FICM) monitors the fuel rail pressure (FRP) sensor voltage, and the fuel rail temperature (FRT) sensor voltage. When the FICM detects a condition with the FRP or FRT sensors, the diagnostic data is communicated to the PCM by a dedicated pulse width modulated (PWM) circuit.

This DTC sets when the FICM diagnostic output PWM signal is not received by the PCM.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC
    • The FICM diagnostic output PWM signal is not received by the PCM.
    • The condition exists for at least 5 seconds.

Action Taken When the DTC Sets
    • The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
    • The control module switches over to gasoline fuel operation.
    • The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

Conditions for Clearing the MIL/DTC
    • The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
    • A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
    • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
    • Clear the MIL and the DTC with a scan tool.

Test Description

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

  1. This step determines if the condition is present.

    2.

  2. If any of the listed DTCs are set, diagnose those DTCs first.

    3.

  3. This step verifies that the FICM is supplying the correct output voltage. The open circuit voltage should be 5.0 volts.

Step

Action

Value(s)

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Engine Controls Connector End Views

1

Did you perform the Diagnostic System Check Alternative Fuels - Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Alternative Fuels (Engine Controls)

2

Observe the FICM diagnostic circuit status with a scan tool.

Does the scan tool display FAULT?

--

Go to Step 3

Go to Step 4

3

Are any of the DTCs P0187, P0188, P0191, P0192, P0193, P0611, or P1208 also set?

--

Go to Diagnostic Trouble Code (DTC) List

Go to Step 5

4
  1. Observe the Freeze Frame and/or the Failure records data for this DTC.
  2. Turn the ignition OFF for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame and/or the Failure records data.

Does the DTC fail this ignition cycle?

--

Go to Step 5

Go to Intermittent Conditions

5

  1. Turn OFF the ignition.
  2. Disconnect the PCM harness connector C2. Refer to Powertrain Control Module Replacement in Engine Controls in the G/H Van Service Manual.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the FICM diagnostic output PWM circuit with a DMM.

Does the DMM display the voltage at the specified value?

5.0 V

Go to Step 9

Go to Step 6

6

Is the voltage more than the specified value?

5.3 V

Go to Step 8

Go to Step 7

7

Test for an open, or a short to ground on the FICM diagnostic output PWM circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems in the G/H Van Service Manual.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 10

8

Test for a short to voltage on the FICM diagnostic output PWM circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems in the G/H Van Service Manual.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 12

9

Inspect for proper terminal contact at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems in the G/H Van Service Manual.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 11

10

Inspect for proper terminal contact at the harness connector of the FICM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems in the G/H Van Service Manual.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 12

11

Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls in the G/H Van Service Manual.

Did you complete the replacement?

--

Go to Step 13

--

12

Replace the FICM. Refer to Fuel Injector Control Module Replacement .

Did you complete the replacement?

--

Go to Step 13

--

13
  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30  seconds.
  3. Turn ON the ignition, with the engine OFF.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

--

Go to Step 2

Go to Step 14

14

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK