I just had my truck in the shop yesterday for the dreaded spark plug change. I did not have time (or desire) to do it myself.

Today I left work and got a P0193 code and Check Engine light.

I hooked up a scan tool and the Fuel Rail pressure reads 77 PSI, the truck ran and runs fine the whole way home.

I disconnected the Fuel Rail Pressure Monitor from the harness and thought the pressure would read zero but Live data readout went from 77 to 78 PSI. So it looks like the VREF Return and Signal are communicating to the PCM I just thought it would read 0 since the reference was gone... I may have interpreted the chart I found wrong.
Any ideas what it could be or how to test the PCM?

I cannot find a schrader valve to plug a fuel pressure gauge in but would like to test that. Does anyone know where/how to do that on the 5.4 3V Triton?


Trouble Code Triggering Freeze Frame:
P0193: Fuel Rail Pressure Sensor Circuit High Bank 1
Freeze Frame Data:
· PID : Description : Value
· 01 : Monitor Status Since DTCs Cleared : 0
· 03 : Fuel System Status : Open loop due to insufficient engine temperature
· 04 : Calculated Engine Load Value : 40.4 %
· 05 : Engine Coolant Temperature : 90 °C, 194 °F
· 06 : Short Term Fuel Trim Bank 1 : 0.0 %
· 07 : Long Term Fuel Trim Bank 1 : -3.9 %
· 08 : Short Term Fuel Trim Bank 2 : 0.0 %
· 09 : Long Term Fuel Trim Bank 2 : -5.5 %
· 0C : Engine RPM : 661 rpm
· 0D : Vehicle Speed : 0 km/h, 0 MPH
· 0E : Timing Advance for #1 cylinder : 4.0 °
· 0F : Intake Air Temperature : 45 °C, 113 °F
· 10 : Mass Air Flow Rate : 8.68 g/s, 1.15 lb/min
· 11 : Absolute Throttle Position : 13.7 %
· 14 : O2 Bank 1 - Sensor 1 - Short Term Fuel Trim : 0.0 %
· 14 : O2 Bank 1 - Sensor 1 - Oxygen Sensor Voltage : 0.770 V
· 15 : O2 Bank 1 - Sensor 2 - Short Term Fuel Trim : 99.2 %
· 15 : O2 Bank 1 - Sensor 2 - Oxygen Sensor Voltage : 0.810 V
· 18 : O2 Bank 2 Sensor 1 (Bank 3 Sensor 1) Short Term Fuel Trim : 0.0 %
· 18 : O2 Bank 2 Sensor 1 (Bank 3 Sensor 1) Oxygen Sensor Voltage : 0.755 V
· 19 : O2 Bank 2 Sensor 2 (Bank 3 Sensor 2) Short Term Fuel Trim : 99.2 %
· 19 : O2 Bank 2 Sensor 2 (Bank 3 Sensor 2) Oxygen Sensor Voltage : 0.780 V
· 1F : Run Time Since Engine Start : 8 seconds
· 22 : Fuel Rail Pressure (relative to manifold vacuum) : 535.857 kPa, 77.719 PSI
· 2E : Commanded Evaporative Purge : 0.0 %
· 2F : Fuel Level Input : 38.8 %
· 30 : # of Warm-ups Since Codes Cleared : 0 #
· 31 : Distance Traveled Since Codes Cleared : 1 km, 1 mile
· 32 : Evap. System Vapor Pressure : -42.8 Pa, -0.2 inH O ₂
· 33 : Barometric Pressure : 101 kPa, 30 inHg
· 3C : Catalyst Temperature Bank 1 - Sensor 1 : 503.8 °C, 938.8 °F
· 3D : Catalyst Temperature Bank 2 - Sensor 1 : 503.8 °C, 938.8 °F
· 41 : Monitor Status this Drive Cycle : 0
· 42 : Control Module Voltage : 13.508 V
· 43 : Absolute Load Value : 22.7 %
· 44 : Commanded Equivalence Ratio : 0.999 λ
· 45 : Relative Throttle Position : 2.7 %
· 46 : Ambient Air Temperature : 32 °C, 90 °F
· 47 : Absolute Throttle Position B : 17.6 %
· 49 : Accelerator Pedal Position D : 18.0 %
· 4A : Accelerator Pedal Position E : 29.0 %
· 4B : Accelerator Pedal Position F : 17.6 %
· 4C : Commanded Throttle Actuator : 4.3 %









Thanks for the help!

 

I did a little more digging.

I disconnected the connector, it is a 4 pin connector like in the image below.


Pin 1, 2 and 3 all read 5 volts to pin 4 when disconnected from the sensor....

Ideas??

Thanks,

Brian

 

There is no Schrader valve on the 04+ trucks.

Have you checked the FPDM for corrosion?

 

I figured as much.. Oh well.


Do you think the FPDM could be the cause when the PCM is sending 5 volts on the other sensor outputs?


As I mentioned, when I disconnected the FRPT sensor from the harness and tested the harness cables there was 5 volts on pins 1, 2 and 3 when measured to pin 4 or chassis ground.


The way I read the troubleshooting procedure was to test pin 1 and 4 and verify no voltage. This was a Chiltons service manual so it may be incorrect but I would think those pins should be inputs to the harness not a voltage to the sensor.

I am taking the truck back to the shop that did the spark plugs today to see what they say.


Brian