GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2004 🢒 Chevy K Silverado - 4WD (CNG) 🢒 Engine 🢒 Engine Controls - 6.0L 🢒 DTC P1207

Circuit Description

The fuel injector control module (FICM) monitors the compressed natural gas (CNG) fuel tank pressure (FTP) sensor, the fuel tank temperature (FTT) sensor, and the fuel rail temperature (FRT) sensor. The FTP, FTT, and FRT sensor values, and FICM diagnostic status, is communicated to the powertrain control module (PCM) by 2 pulse width modulated (PWM) circuits.

This DTC sets when the sensor value PWM output signal is not received by the PCM.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P1207 Fuel Injector Control Module Sensor Signal Circuit 1

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC
    • The sensor value PWM output signal is not received by the PCM.
    • The condition exists for at least 2 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 fuel injector control module (FICM) is powered ON. A loss of power or ground to the FICM may set this DTC. A KL6 vehicle may start on gasoline after several seconds.

    2.

  2. This step determines if the condition is present.

    3.

  3. This step verifies that the PCM is supplying the correct output voltage. The open circuit voltage should be 5 volts.

Step

Action

Values

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

  1. Clear the DTC information with a scan tool.
  2. Turn the ignition OFF for 30 seconds.
  3. Attempt to start and idle the engine on compressed natural gas (CNG). Crank the engine for up to 15 seconds if required.

Does the engine only operate on gasoline or is DTC P0611 set?

--

Go to DTC P0611

Go to Step 3

3

Observe the FICM odd bank circuit status with a scan tool.

Does the scan tool display FAULT?

--

Go to Step 5

Go to Step 4

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 fuel injector control module (FICM) harness connector. Refer to Fuel Injector Control Module Replacement .
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the pulse width modulated (PWM) output circuit with a DMM.

Does the DMM display the voltage at the specified value?

5 V

Go to Step 10

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 PWM output circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems in the C/K Pickup Service Manual.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 9

8

Test for a short to voltage on the PWM output circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems in the C/K Pickup Service Manual.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 11

9

Inspect for proper terminal contact at the harness connector of the powertrain control module (PCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems in the C/K Pickup 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 C/K Pickup 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 C/K Pickup 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