DTC P2146 w/o JL4
Circuit Description
The powertrain control module (PCM) grounds the AFO enable circuit when operating on compressed natural gas (CNG). When the AFO enable circuit is grounded the fuel injector control module (FICM) will operate the CNG injectors based upon the PCM pulse width signals. The PCM controls alternative fuel operation by grounding the AFO enable circuit via an internal switch called a driver. The primary function of the driver is to supply the ground for the controlled component. The PCM monitors the status of the driver. If the PCM detects an incorrect voltage for the commanded state of the driver, DTC P2146 sets.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P2146 Injector Positive Voltage Control Circuit
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
| • | The PCM detects that the commanded state of the driver and the actual state of the control circuit do not match. |
| • | The above condition exists for at least 1 seconds. |
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the 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 tests if the concern is active.
-
This step tests if a ground is constantly being applied to the AFO enable circuit. With the FICM disconnected, the PCM will command gasoline operation. The AFO enable circuit should not illuminate the test lamp.
-
This step verifies that the PCM is providing ground to the AFO enable circuit.
The values specified indicate typical monitored values.
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) |
Does the scan tool display DTC P0611? | -- | Go to DTC P0611 | Go to Step 3 | |
3 |
Did the DTC fail this ignition? | -- | Go to Step 4 | Go to Intermittent Conditions |
Important: Other DTCs may set. Does the test lamp illuminate? | -- | Go to Step 7 | Go to Step 5 | |
Does the circuit resistance change from a higher value on gasoline (OFF) to a lower value on alternative fuel (ON)? | 3,000 ohms 75 ohms | Go to Step 8 | Go to Step 6 | |
6 | Test the AFO enable circuit for an open or for a short to voltage. 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 12 | Go to Step 9 |
7 | Test the AFO enable circuit for a short to ground. 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 12 | Go to Step 11 |
8 | Inspect for poor connections 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 12 | Go to Step 10 |
9 | Inspect for poor connections at the harness connector of thepowertrain control module (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 12 | Go to Step 11 |
10 | Replace the FICM. Refer to Fuel Injector Control Module Replacement . Did you complete the replacement? | -- | 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 12 | -- |
12 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 13 |
13 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |
