DPFE

2002 f150 I have put 3 DPFE solenoids I this truck P0405 low voltage sensor A I believe it is a bad ground I'm at a loss as what to do! I need HELP! Any ideas on what to do next? Thanks

Time for some voltage checks!

Key on, engine not running, DPFE disconnected, multimeter ground connected to B-, check all three DPFE pins for voltage. Report back and we can guide you further.

5 volt at control, 0 @ ground, .73-.98 at signal wire

Gotcha, thank you.

Now your goal is to determine if you have a wiring fault causing the low voltage (high resistance or partial short), or a PCM that isn't supplying the correct bias voltage. A voltage check at the PCM is next.

I'll grab the diagram later on today.

What's the 8th digit of your VIN?

For the 4.6L, Pin 1 is the sensor signal wire at the DPFE sensor connector. Hopefully, that's the wire you found .73-.98V. It's a brown/light green. That wire ends up at pin 65 at the PCM. That brown/light green sits in between a light blue/yellow and a yellow/light green. When you find that wire color sequence, you'll know you're on the right wire.

Disconnect the PCM and DPFE, and check for opens and shorts with the multimeter. We're specifically interested in resistance between the two, and resistance to B-. Resistance between the two should be less than 5 ohms. Resistance to ground should be infinite.