Circuit Description
The fuel injector control module (FICM) monitors the CNG fuel injector circuits. The CNG fuel injector circuit status and internal FICM diagnostic data, is communicated to the powertrain control module (PCM) by a 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 voltage is between 6 and 18 volts.
Conditions for Setting the DTC
| • | The FICM diagnostic output PWM 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.
-
This step determines if the condition is present.
-
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) |
Observe the FICM diagnostic circuit status with a scan tool. Does the scan tool display FAULT? | -- | Go to Step 4 | Go to Step 3 | |
3 |
Does the DTC fail this ignition cycle? | -- | Go to Step 4 | Go to Intermittent Conditions |
Does the DMM display the voltage at the specified value? | 5.0 V | Go to Step 11 | Go to Step 5 | |
5 | Is the voltage more than the specified value? | 5.3 V | Go to Step 10 | Go to Step 6 |
6 |
Does the test lamp illuminate? | Go to Step 7 | Go to Step 13 | |
7 | Probe the battery voltage circuit of the FICM with a test lamp connected to a good ground. Does the test lamp illuminate? | -- | Go to Step 8 | Go to Step 14 |
8 | Probe the ground circuits of the FICM with a test lamp connected to B+. Does the test lamp illuminate for each circuit? | -- | Go to Step 9 | Go to Step 15 |
9 | 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 J Platform Service Manual. Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 12 |
10 | 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 J Platform Service Manual. Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 17 |
11 | 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 J Platform Service Manual. Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 16 |
12 | 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 J Platform Service Manual. Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 17 |
13 | Repair the open or short to ground on the ignition voltage circuit of the FICM. Refer to Wiring Repairs in Wiring Systems in the J Platform Service Manual. Did you complete the repair? | -- | Go to Step 18 | -- |
14 | Repair the open or short to ground on the battery voltage circuit of the FICM. Refer to Wiring Repairs in Wiring Systems in the J Platform Service Manual. Did you complete the repair? | -- | Go to Step 18 | -- |
15 | Repair the open on the ground circuit of the FICM. Refer to Wiring Repairs in Wiring Systems in the J Platform Service Manual. Did you complete the repair? | -- | Go to Step 18 | -- |
16 | Replace the PCM. Refer to Powertrain Control Module Replacement in the J Platform Service Manual. Did you complete the replacement? | -- | Go to Step 18 | -- |
17 | Replace the FICM. Refer to Fuel Injector Control Module Replacement . Did you complete the replacement? | -- | Go to Step 18 | -- |
18 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 19 |
19 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |
