present, go to step 48). If FPM PID value is not 75 percent or is not varying between 250-400 percent,
DTC P1237, P1238 or P1641 is intermittent, go to next step.
57) Check Fuel Pump Secondary Circuits For Intermittent Open Or Short
Turn ignition switch to ON position. Using scan tool, access FPM PID from PID/DATA MONITOR &
RECORD menu. Observe FPM PID value for indication of fault while wiggling and bending FP PWR
and FP RTN circuits between FPDM and fuel pump. Lightly tap on FPDM to simulate road shock. Fault
will be indicated by FPM PID value changing from 50 percent, or varying between 85-115 percent. If any
faults are found, isolate fault and repair as necessary. If no faults are found, go to next step.
58) Check FP PWR Circuit For Short To Ground
Turn ignition switch to OFF position. Disconnect FPDM. Connect a test light between FP PWR and
FPDM PWR circuits at FPDM harness connector. Turn ignition switch to ON position. Observe test light
for indication of fault while wiggling and bending FP PWR circuit between FPDM and fuel pump. If a
fault is indicated, test light will illuminate (indicating short to ground). If any faults are found, isolate
fault and repair as necessary. If no faults are found, concern cannot be identified at this time. Turn
ignition switch to OFF position, reconnect FPDM and go to TEST Z, step 1).
59) Check FP PWR Circuit For Short To PWR
Turn ignition switch to OFF position. Disconnect FPDM connector. Turn ignition switch to ON position.
Using a DVOM, measure voltage between chassis ground and FP PWR circuit at FPDM harness
connector. See Fig. 308-Fig. 311 . If voltage is less than one volt, go to next step. If voltage is one volt or
more, repair FP PWR circuit for short to PWR.
60) Check FP RTN Circuit For Short To Ground
Ensure ignition switch is turned to ON position. Using a DVOM, measure voltage between FPDM PWR
and FP RTN circuits at FPDM harness connector. If voltage is less than one volt, replace FPDM. If
voltage is one volt or more, repair short to ground in FP RTN circuit.
61) Check REM/FP PWR & GND Circuit To REM Harness Connector C420d (LS) or C420e
(Thunderbird) Terminals No. 1 & 2
Ensure Inertia Fuel Shutoff (IFS) switch is not tripped. Disconnect REM connector C420d (LS) or C420e
(Thunderbird). See Fig. 312. Turn ignition switch to ON position. Using a DVOM, measure voltage
between REM/FP PWR and GND circuits at REM harness connector C420d (LS) or C420e
(Thunderbird). If voltage is 10.5 volts or less, go to next step. If voltage is more than 10.5 volts, go to step
49).
62) Check REM/FP PWR Circuit Voltage To REM Using Chassis Ground As A Reference
NOTE:
With no fault detected, FPDM will send a 50 percent duty cycle signal on
FPM circuit to PCM. FPM PID value should display 50 percent. Depending
on scan tool being used, some scan tools will display a random value
between 85-115 percent.
2003 Ford Pickup F150
2003 ENGINE PERFORMANCE Self-Diagnostics - CNG, Flex-Fuel & Gasoline