P1020

DTC P1020

CIRCUIT DESCRIPTION
The powertrain control module (PCM) controls fuel delivery and determines fuel system operation on bi-fuel (KL6) vehicles. The PCM is not capable of operating the high current compressed natural gas (CNG) fuel injectors. The 8 PCM injector pulse width modulated (PWM) signals are received by the fuel injector control module (FICM) and duplicate PWM signals are generated by the FICM in order to operate the CNG injectors. Ignition voltage is supplied to the fuel injectors. The FICM controls each CNG fuel injector by grounding the control circuit via a solid state device called a driver. The FICM monitors the status of each PWM input signal. If the control module does not receive a fuel injector PWM signal from the PCM DTC P1020 sets.

DTC DESCRIPTOR
This diagnostic procedure supports the following DTC:
DTC P1020 Injector Output Circuit

CONDITIONS FOR RUNNING THE DTC
- DTCs P0148, P0611, or P1209 are not set.
- The ignition voltage is between 6-18 volts.
- The engine is operating on CNG.
- The PCM is not in fuel shut-off, or decel fuel cut-off mode.

CONDITIONS FOR SETTING THE DTC
- The FICM detects a condition on a fuel injector PWM input signal.
- The condition exists for 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.

DIAGNOSTIC AIDS
- A stuck AF injector relay may cause this DTC to set.
- For an intermittent condition, refer to Intermittent Conditions. Intermittent Conditions

TEST DESCRIPTION

Step 1 - Step 9:

Step 10 - Step 20:

The numbers below refer to the step numbers on the diagnostic table.
3. If DTC P0200 also sets, diagnose P0200 first. A PWM circuit condition between the AF injector relay and the PCM will cause DTCs P0200 and P1020 to set.
5. This step determines if the condition is causing an engine misfire. The AF fuel mode relay must be removed in order to prevent a fuel system switch-over.
6. This step tests the ignition feed circuit to the AF fuel mode relay. An open ignition feed circuit to the relay will set this DTC.
7. This step tests the AF enable circuit to the FICM. An open AF enable circuit between the splice and FICM will set this DTC without an engine misfire.
9. This step verifies that the FICM is receiving the PWM input signal from the PCM. The test lamp should blink while the engine is cranking.