Accelerator, Brake And Throttle Position Sensor Inputs

There are 2 pedal position sensors in the pedal assembly. Both signals, APP1 and APP2, have a positive slope (increasing angle, increasing voltage), but are offset and have different slope. There are 2 reference voltage circuits, 2 signal return circuits, and 2 signal circuits (a total of 6 circuits and pins) between the PCM and the APP sensor assembly. The pedal position signal is converted to pedal travel degrees (rotary angle) by the PCM.

The Brake Pedal Position (BPP) Switch (Brake On/Off) is sometimes referred to as the stop lamp switch. The BPP switch provides a signal to the PCM indicating the brakes are applied. The BPP switch is a normally open switch and is mounted on the brake pedal support. The BPP switch supplies battery positive (B+) voltage to the PCM when the brake pedal is applied. The normally closed BPS (brake pressure switch), along with the normally open BPP switch, are used for a brake rationality test within the PCM. If one or both brake pedal inputs to the PCM is not changing states as expected, a P0504 DTC is set. BPP is used by the ETC strategy (Electronic Throttle Control) for the Brake Override Accelerator (BOA) feature. Failure of the BOO switch may result in decreased driveability but it does not impact emissions or OBD.

The brake pressure switch is a normally closed switch which is typically mounted on the brake pedal support. When the brake pedal is applied, the normally closed switch opens. BPS is used for cruise control deactivation, by transmission for trailer brake control & tow haul mode, and is used in Stop/Start applications for brake pressure indication. It is not used for OBD.

Analog Throttle Position 

The Electronic Throttle Body has two throttle position sensor circuits. One sensor (TP1) has a negative slope (increasing angle, decreasing voltage) and the second sensor (TP2) has a positive slope (increasing angle, increasing voltage). Two sensors are used for redundancy.

SENT Throttle Position 

The 2017 MY 3.5L GTDI F150 is using a SENT Throttle Position Sensor. This is considered to be a Smart Device" by the OBD-II regulations. The analog throttle position sensor signals have been replaced by a three wires - a 5 volt reference voltage, a ground and a SENT communication line. The DTC structure is similar but not the same.

Sensor faults identified by the SENT device use the traditional P-codes, P0120 and P0124. Because of the safety related nature of throttle position faults, note that the P0124 DTC sets immediately, as soon as a fault is initially recognized and FMEM actions are taken. If the fault persists, another DTC identifying the specific fault will be set as well.

If communication is lost with the SENT device, the U0606 (lost communication) code would be set. Most likely, it means that there is a wiring issue even though it could also mean the SENT device failed or lost power/ground and is no longer communicating with the PCM. The service technician would proceed to troubleshoot the wires, but if no wiring fault could be identified, the next action would be to replace the SENT device.

SENT communication uses CRC errors to identify a communication fault. A CRC fault could be caused either by faulty wiring or by a faulty SENT microprocessor. CRC errors would also set the U0606 (lost communication) code. Similarly, the service technician would proceed to troubleshoot the wires, but if no wiring fault could be identified, the next action would be to replace the SENT device.

Two additional DTCs (U210F and U2110) to identify if the SENT communication line is shorted high or low.