Mechanical RETURNLESS Fuel System (MRFS) - Dual Speed (2015)
The FP signal is a duty cycle command sent from the PCM to the fuel pump control module. The fuel pump control module uses the FP command to operate the fuel pump at the speed requested by the PCM or to turn the fuel pump off. A valid duty cycle to command the fuel pump on, is in the range of 15-47%. The fuel pump control module doubles the received duty cycle and provides this voltage to the fuel pump as a percent of the battery voltage. When the ignition is turned on, the fuel pump runs for about 1 second and is requested off by the PCM if engine rotation is not detected.
| FP Duty Cycle Command | PCM Status | Fuel Pump Control Module Actions |
| 0-15% | Invalid off duty cycle | The fuel pump control module sends a 20% duty cycle signal on the fuel pump monitor (FPM) circuit. The fuel pump is off. |
| 37% | Normal low speed operation. | The fuel pump control module operates the fuel pump at the speed requested. The fuel pump control module sends a 60% duty cycle signal on FPM circuit. |
| 47% | Normal high speed operation. | The fuel pump control module operates the fuel pump at the speed requested. The fuel pump control module sends a 60% duty cycle signal on FPM circuit. |
| 51-67% | Invalid on duty cycle. | The fuel pump control module sends a 20% duty cycle signal on the FPM circuit. The fuel pump is off. |
| 67-83% | Valid off duty cycle | The fuel pump control module sends a 60% duty cycle signal on FPM circuit. The fuel pump is off. |
| 83-100% | Invalid on duty cycle. | The fuel pump control module sends a 20% duty cycle signal on the FPM circuit. The fuel pump is off. |
The fuel pump control module communicates diagnostic information to the PCM through the FPM circuit. This information is sent by the fuel pump control module as a duty cycle signal. The 4 duty cycle signals that may be sent are listed in the following table.
| Duty Cycle | Comments |
| 20% | This duty cycle indicates the fuel pump control module is receiving an invalid duty cycle from the PCM. |
| 40% | For vehicles with event notification signal, this duty cycle indicates the fuel pump control module is receiving an invalid event notification signal from the RCM. For vehicles without event notification signal, this duty cycle indicates the fuel pump control module is functioning normally. |
| 60% | For vehicles with event notification signal, this duty cycle indicates the fuel pump control module is functioning normally. |
| 80% | This duty cycle indicates the fuel pump control module is detecting a concern with the secondary circuits. |
| DTCs | P025A - Fuel Pump Control (open/shorts) P025B - Invalid Fuel Pump Control Data (20% duty cycle from FPM) P0627 - Fuel Pump Secondary Circuit (80% duty cycle from PFM) U2010B - Fuel Pump Disabled Circuit (40% duty cycle from FPM) U0109 - Loss of Communication with Fuel Pump Module |
| Monitor Execution | once per driving cycle |
| Monitor Sequence | None |
| Sensors OK | |
| Monitoring Duration | 2 seconds |
| Entry Condition | Minimum | Maximum |
| Battery Voltage | 11 volts |
| P025A FP output driver indicates fault P025B, P0627, U210B Fuel Pump Monitor duty cycle feedback of 20, 40 or 80% U0191 No Fuel Pump Monitor duty cycle feedback |
There are several different styles of hardware used to control airflow within the engine air intake system. In general, the devices are defined based on whether they control in-cylinder motion (charge motion) or manifold dynamics (tuning). Systems designed to control charge motion are defined to be Intake Manifold Runner Controls. IMRC systems generally have to modify spark when the systems are active because altering the charge motion affects the burn rate within the cylinder. Systems designed to control intake manifold dynamics or tuning are defined to be Intake Manifold Tuning Valves. IMTV systems generally do not require any changes to spark or air/fuel ratio because these systems only alter the amount of airflow entering the engine.