GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2003 🢒 Express (CNG) 🢒 DTC 🢒 DTC P0611

Description

The fuel injector control module (FICM) monitors the fuel rail pressure (FRP) sensor voltage, and the fuel rail temperature (FRT) sensor voltage. The FRP and FRT sensor values, and diagnostic data, is communicated to the powertrain control module (PCM) by 3 pulse width modulated (PWM) circuits. This DTC sets when the PCM does not receive any PWM signals from the FICM.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

The powertrain control module (PCM) detects an incorrect PWM signal on the FICM diagnostic output circuit.

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 number below refers to the step number on the diagnostic table.

  1. This step verifies that the condition is active.

    2.

  2. This step verifies that the ignition voltage circuit to the FICM is OK. If the ignition voltage circuit is open, DTCs P1207, P1208, and P1209 may also be set.

Step

Action

Yes

No

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. Turn ON the ignition with the engine OFF.
  2. Clear the DTC information with a scan tool.
  3. Attempt to start and idle the engine.
  4. Observe the DTC information with a scan tool.

Does DTC P0611 reset?

Go to Step 3

Go to Intermittent Conditions

3
  1. Turn OFF the ignition.
  2. Disconnect the harness connector of the FICM. Refer to Fuel Injector Control Module Replacement .
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the ignition feed circuit of the FICM with a test lamp connected to a good ground.

Does the test lamp illuminate?

Go to Step 4

Go to Step 5

4

Probe the ground circuits of the FICM with a test lamp connected to B+.

Does the test lamp illuminate for both circuits?

Go to Step 7

Go to Step 6

5

Repair the open or short to ground on the ignition feed circuit of the FICM. Refer to Wiring Repairs in Wiring Systems in the G/H Van Service Manual.

Did you complete the repair?

Go to Step 9

--

6

Repair the open on the ground circuit of the FICM. Refer to Wiring Repairs in Wiring Systems in the G/H Van Service Manual.

Did you complete the repair?

Go to Step 9

--

7

Inspect for poor connections at the harness connector of the control module. 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 9

Go to Step 8

8

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

Did you complete the replacement?

Go to Step 9

--

9
  1. Turn OFF the ignition for 30  seconds.
  2. Turn ON the ignition, with the engine OFF.

Did the DTC fail this ignition?

Go to Step 2

Go to Step 10

10

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