Ford F150 Pickup. Instruction - part 1549

LS and Thunderbird). See Fig. 308-Fig. 312 . If resistance is less than 5 ohms, go to next step. If 
resistance is 5 ohms or more, repair open in FP circuit. 

32) Check FP Circuit For Short To PWR In Harness 
 
Turn ignition switch to ON position. Using a DVOM, measure voltage between chassis ground and FP 
circuit at PCM harness connector. If voltage is less than one volt, go to next step. If voltage is one volt or 
more, repair short to PWR in FP circuit. 

33) Check FP Circuit For Short To Ground In Harness 
 
Turn ignition switch to OFF position. Disconnect scan tool from DLC. Using a DVOM, measure 
resistance of FP circuit between PCM harness connector and chassis ground. If resistance is 10 k/ohms or 
less, repair short to ground in FP circuit. If resistance is more than 10 k/ohms, go to step 36) (LS and 
Thunderbird), or go to next step (all others). 

34) Check FP Circuit In FPDM 
 
Reconnect FPDM. Turn ignition switch to ON position. Using a DVOM, measure voltage between PWR 
GND and FP circuits at PCM harness connector. See PCM CONNECTOR IDENTIFICATION and 
Fig. 308-Fig. 312 . See PCM PWR GND, SIG RTN & VREF TERMINAL IDENTIFICATION 
table. If voltage is 4.5-5.5 volts, replace PCM. If voltage is not 4.5-5.5 volts, replace FPDM. 

36) Check FPF PID 
Turn ignition switch to ON position. Using scan tool, access FPF PID from PID/DATA MONITOR & 
RECORD menu. Observe FPF PID for 20 seconds. If FPF PID indicated YES during 20 second time 
period, go to step 40). If FPF PID indicates NO during whole 20 second time period, go to next step. 

37) Check FP PID 
 
Using scan tool, access FP PID from PID/DATA MONITOR & RECORD menu. If FP PID indicates 70-
80 percent, go to next step. If FP PID does not indicate 70-80 percent, cycle ignition switch to OFF, then 
to ON position and wait 5 seconds. Repeat this test step. If FP PID now indicates 70-80 percent, go to 
next step. If FP PID still does not indicate 70-80 percent, replace PCM. 

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips 
from step 34) to step 36). No test procedures have been omitted.

NOTE:

It is okay if FPF PID flashes to NO during 20 second time period and 
changes back to YES.

NOTE:

PWM_DC1 PID indicates signal sent to REM from PCM on FP circuit.

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips 
from step 38) to step 40). No test procedures have been omitted.

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE Self-Diagnostics - CNG, Flex-Fuel & Gasoline

  

38) Access REM PIDs & Check PWM_DC1 PID 
Using scan tool, access PWM_DC1 PID from REM menu. If PWM_DC1 PID indicates 70-80 percent, 
turn ignition switch to OFF position. No fault is indicated. Disregard DTC P1235 or P1236 at this time 
and check for Continuous Memory DTCs. If Continuous Memory DTCs are present, go to appropriate 
system test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS. If Continuous Memory DTCs are 
not present, testing is complete. If PWM_DC1 PID does not indicate 70-80 percent, replace REM. 

40) Check REM Harness Voltage On FP Circuit At PCM 
 
Turn ignition switch to OFF position. Disconnect PCM connector "B". See PCM CONNECTOR 
IDENTIFICATION. Turn ignition switch to ON position. Using a DVOM, measure voltage between 
PCM harness connector terminal B58 and chassis ground. If voltage is more than 8 volts, replace PCM. If 
voltage is 8 volts or less, replace REM. 

42) Check FP Circuit For Intermittent Concerns 
Turn ignition switch to ON position. Using scan tool, access PWM_DC1 PID from REM menu. Observe 
PWM_DC1 PID value for indication of fault while wiggling and bending FP circuit between REM and 
PCM. Fault will be indicated if PWM_DC1 PID value changes. If any faults are found, isolate fault and 
repair as necessary. If no faults are found, check for intermittent fault. Leave scan tool connected, go to 
TEST Z, step 1) and use FP and PWM_DC1 PIDs for diagnosis of intermittent fault. 

45) Check FP Circuit For Intermittent Opens Or Shorts 
Turn ignition switch to ON position. Using scan tool, access FPM PID from PID/DATA MONITOR & 
RECORD menu. Observe FPM PID for indication of fault while wiggling and bending FP circuit 
between FPDM and PCM. Lightly tap on FPDM to simulate road shock. Fault will be indicated if FPM 
PID value changes from 50 percent, or value stops fluctuating. If any faults are found, isolate fault and 
repair as necessary. If no faults are found, concern cannot be duplicated at this time. Go to TEST Z, step 
1). 

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips 
from step 40) to step 42). No test procedures have been omitted.

NOTE:

PWM_DC1 PID indicates signal sent to REM from PCM on FP circuit.

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips 
from step 42) to step 45). No test procedures have been omitted.

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.

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips 
from step 45) to step 47). No test procedures have been omitted.

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE Self-Diagnostics - CNG, Flex-Fuel & Gasoline

  

47) For KOEO, KOER & Continuous Memory DTCs P1237, P1238 & P1641 
These DTCs indicate FPDM has detected a fuel pump secondary circuit fault. Possible causes are: 

z

Open Or Shorted FP PWR Circuit  

z

Open FP RTN Circuit To FPDM  

z

Open Or Shorted Circuit In Fuel Pump  

z

Locked Fuel Pump Rotor  

z

Faulty FPDM  

z

On LS & Thunderbird, Circuits Associated With Fuel Pump Relay  

If DTC P1237, P1238 or P1641 is present in KOEO or KOER self-test, the DTC is a hard fault. Go to 
next step. If DTC P1237, P1238 or P1641 is not present in KOEO or KOER self-test, check for 
intermittent fault. Go to step 

67)

 (LS and Thunderbird), or go to step 56) (all others). 

48) Attempt To Start Engine 
 
Attempt to start engine. If engine starts, go to step 80) (LS and Thunderbird), or go to step 59) (all 
others). If engine is a no-start, go to step 61) (LS and Thunderbird), or go to next step (all others) to 
diagnose fuel pump secondary circuits. 

49) Check FP PWR, FP RTN & Internal Fuel Pump Circuit Resistance 
Turn ignition switch to OFF position. Disconnect scan tool from DLC. Disconnect FPDM (or 20-pin 
REM) connector. Using a DVOM, measure resistance between FP PWR and FP RTN circuits at FPDM 
(or REM) harness connector. See Fig. 308-Fig. 312 . If resistance is less than 10 ohms, go to next step. If 
resistance is 10 ohms or more, an open in secondary circuit exists. Go to step 54) to isolate fault. 

50) Check FP RTN Circuit For Short To PWR In Harness 
 
Turn ignition switch to ON position. Using a DVOM, measure voltage between chassis ground and FP 
RTN circuit at FPDM (or REM) harness connector. If voltage is less than one volt, go to next step. If 
voltage is one volt or more, repair short to PWR. 

NOTE:

For additional testing information, see DIAGNOSTIC AIDS.

NOTE:

DTC P1237 and P1238 are identical, except DTC P1238 will not illuminate 
Malfunction Indicator Lamp (MIL). On LS and Thunderbird, FPDM functions 
are incorporated in Rear Electronics Module (REM). Also, REM does not 
use an FPM circuit. Diagnostic information will be sent through SCP 
network. See Fig. 308-Fig. 312 .

NOTE:

If directed here from step 61), FPDM functions are incorporated in Rear 
Electronics Module (REM) for LS and Thunderbird. If directed to perform 
an FPDM action, perform action using REM. Refer to illustration. See Fig. 
312 for REM module circuit and terminal identification.

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE Self-Diagnostics - CNG, Flex-Fuel & Gasoline

  

51) Check FP PWR Circuit For Short To Ground In Harness 
 
Turn ignition switch to OFF position. Disconnect fuel pump connector. Using a DVOM, measure 
resistance of FP PWR circuit between FPDM (or REM) harness connector and chassis ground. If 
resistance is more than 10 k/ohms, go to next step. If resistance is 10 k/ohms or less, repair FP PWR 
circuit for short to ground. 

52) Check For VPWR To Fuel Pump 
Reconnect FPDM (or REM) and scan tool. Turn ignition switch to ON position. Connect DVOM between 
FP PWR and FP RTN circuits at fuel pump harness connector. Using scan tool, access OUTPUT TEST 
MODE. See OUTPUT TEST MODE under ADDITIONAL SYSTEM FUNCTIONS. Use scan tool and 
command OUTPUTS ON (or if no scan tool is available cycle ignition switch to ON position). Fuel pump 
should turn on for about 5 seconds (one second with ignition cycle). With fuel pump commanded ON, if 
voltage is more than 10 volts, replace fuel pump. If voltage is 10 volts or less, verify vehicle battery is 
fully charged. Ensure fuel pump command ON time did not time-out before voltage check was made. If 
battery charge is okay and command ON time did not time-out, replace FPDM. 

54) Isolate Open Circuit 
 
Turn ignition switch to OFF position. Disconnect fuel pump. Using a DVOM, measure resistance of FP 
PWR circuit and of FP RTN circuit between fuel pump harness connector and FPDM (or REM) harness 
connector. See Fig. 308-Fig. 312 . Using a DVOM, measure internal resistance of fuel pump. If all 
resistance measurements are less than 10 ohms, no fault is detected at this time. Verify results of previous 
steps. If any resistance measurement is 10 ohms or more, repair open in FP PWR or FP RTN circuit, or if 
open is internal of fuel pump, replace fuel pump. 

56) Check For Intermittent DTC P1237, P1238 Or P1641 
Turn ignition switch to ON position. Using scan tool, access FPM PID from PID/DATA MONITOR & 
RECORD menu. If FPM PID value is 75 percent or is varying between 250-400 percent, a hard fault is 

NOTE:

To perform this test step without a scan tool, fuel pump can be 
commanded ON for one second by cycling ignition switch from OFF to ON 
position and repeating as necessary.

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips 
from step 52) to step 54). No test procedures have been omitted.

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips 
from step 54) to step 56). No test procedures have been omitted.

NOTE:

When FPDM is detecting a secondary fuel pump circuit fault (wires going 
to fuel pump), a 75 percent duty cycle signal will be sent to PCM on FPM 
circuit. FPM PID value should display 75 percent. Depending on scan tool 
being used, some scan tools will display a random value between 250-400 
percent.

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE Self-Diagnostics - CNG, Flex-Fuel & Gasoline