Ford F150 Pickup. Instruction — part 1542

Fig. 307: Identifying ISO Micro Relay Terminals
Courtesy of FORD MOTOR CO.

2) Check Fuel Pump Relay
Turn ignition switch to OFF position. On ISO micro fuel pump relay terminals that are numbered 1-5,
measure resistance between relay terminal No. 1 and all other relay terminals. Resistance should be 40-
120 ohms between terminals No. 1 and 2 and more than 10 k/ohms between terminal No. 1 and all other
relay terminals. On ISO mini fuel pump relay terminals that are numbered 30, 85, 86, 87 and 87A,
measure resistance between relay terminal No. 85 and all other relay terminals. Resistance should be 40-
120 ohms between terminals No. 85 and 86 and more than 10 k/ohms between terminal No. 85 and other
relay terminals. On both relays, if resistance is not as specified replace relay. If resistance is as specified,
go to next step.

3) Check Fuel Pump (FP) Circuit For Short To PWR In Harness

Disconnect PCM connector(s). Inspect connector for loose, damaged or corroded terminals. Repair as
necessary. Turn ignition switch to ON position. Using a DVOM, measure voltage between chassis ground
and FP circuit at fuel pump relay harness connector. See Fig. 299-Fig. 304 . 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.

2003 Ford Pickup F150

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

4) Check FP Circuit For Short To Ground In Harness

Turn ignition switch to OFF position. Disconnect scan tool from Data Link Connector (DLC). Using a
DVOM, measure resistance between chassis ground and FP circuit at fuel pump relay harness connector.
If resistance is more than 10 k/ohms, go to next step. If resistance is 10 k/ohms or less, repair short to
ground in FP circuit.

5) Check FP Circuit For Open In Harness

Using a DVOM, measure resistance of FP circuit between fuel pump relay cavity and PCM harness
connector. See Fig. 299-Fig. 304 . If resistance is less than 5 ohms, go to next step (KOEO DTC P0231
or P0232 is also present with DTC P0230), or replace PCM (all others). If resistance is 5 ohms or more,
repair open in FP circuit.

6) Check Fuel Pump Primary Circuit Inside PCM
Reconnect PCM harness connector and fuel pump relay. Connect scan tool to DLC. Turn ignition switch
to ON position. Using scan tool, access FPF PID from PID/DATA MONITOR & RECORD menu. If FPF
PID value indicates YES, a fault exists inside of PCM. Replace PCM. If FPF PID value indicates NO, go
to next step.

7) Check Fuel Pump Primary Circuit Inside PCM While Cranking Engine
Using scan tool, observe FPF PID value while cranking engine. If FPF PID value indicates YES during
cranking, replace PCM. If FPF PID value indicates NO during cranking, fuel pump primary circuit is
okay in harness and PCM. For KOEO DTC P0231, go to step 20). For KOEO DTC P0232, go to step 10).

10) For KOEO & KOER Only DTC P0232: Attempt To Start Engine
DTC P0232 indicates that PCM detected high FPM circuit voltage when fuel pump was commanded
OFF. Possible causes are:

z

Inertia Fuel Shutoff (IFS) switch open or not reset.

z

Open circuit between fuel pump and FPM connection to FP PWR circuit.

z

Poor fuel pump ground.

NOTE:

Test steps 6) and 7) will check FP circuit in PCM. To perform this test, FPF
PID will be monitored using scan tool. FPF PID is able to monitor FP circuit
and will indicate when a fault is detected.

NOTE:

Scan tool must be connected to a reliable power source that is powered
with ignition switch in START (crank) position; such as vehicle battery.
Ensure vehicle battery is fully charged.

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips
from step 7) to step 10). No test procedures have been omitted.

NOTE:

For additional testing information, see DIAGNOSTIC AIDS.

2003 Ford Pickup F150

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

z

Fuel pump internally open.

z

Fuel pump secondary circuits shorted to PWR.

z

Fuel pump relay contacts always closed.

z

Open FPM circuit between PCM and connection to FP PWR circuit.

z

Faulty low speed fuel pump relay or related circuits (F150 Lightning 5.4L SC).

z

Faulty PCM (Engine will start).

Attempt to start engine. If engine starts, go to next step. If engine does not start, go to step 65) (F150
Lightning 5.4L SC), or go to step 15) (all others).

11) Verify That Fuel Pump Is Off

Turn ignition switch to ON position and wait 5 seconds. Listen for operational noise from fuel pump
(listen near fuel tank if necessary). If fuel pump operates with ignition switch turned to ON position, go to
next step. If fuel pump does not operate with ignition switch turned to ON position, go to step 13).

12) Check For Fuel Pump Relay Always Closed

Turn ignition switch to OFF position. Remove fuel pump relay from instrument panel relay block (F250-
F550 Pickup), or battery junction box in engine compartment (all others). Turn ignition switch to ON
position. Listen for operational noise from fuel pump. If fuel pump operates, repair short to PWR in FP
PWR or FPM circuit. If fuel pump does not operate, replace fuel pump relay.

13) Check For Open FPM Circuit

Turn ignition switch to OFF position. Remove fuel pump relay from instrument panel relay block (F250-
F550 Pickup), or battery junction box in engine compartment (all others). Disconnect PCM connector.
Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Using a DVOM,
measure resistance of FPM circuit between PCM harness connector and fuel pump relay circuit cavity.
See Fig. 299-Fig. 304 . If resistance is less than 5 ohms, replace PCM (for DTC P0231), or go to next
step (for DTC P0232). If resistance is 5 ohms or more for either DTC, repair open in FPM circuit.

14) Check FPM Circuit In PCM

Reconnect PCM harness connector and reinstall fuel pump relay. Turn ignition switch to ON position.
Using scan tool, access FPM PID from PID/DATA MONITOR & RECORD menu. If FPM PID value
indicates ON, replace PCM. If FPM PID value indicates OFF, go to step 55) (F150 Lightning 5.4L SC),
or no fault is indicated at this time (all others). Fuel pump primary circuit is okay in harness and PCM.
Testing is complete. Disregard DTC P0232 at this time. Repeat QUICK TEST.

15) Check IFS Switch

Turn ignition switch to OFF position. Disconnect IFS switch connector. Ensure IFS switch is reset. Using
a DVOM, measure resistance between IFS switch terminals. If resistance is less than 5 ohms, go to next
step. If resistance is 5 ohms or more, reset or replace IFS switch as necessary.

2003 Ford Pickup F150

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

16) Check For Open FP PWR Circuit Between IFS Switch & Fuel Pump Relay

Remove fuel pump relay from instrument panel relay block (F250-F550 Pickup), or battery junction box
in engine compartment (all others). Using a DVOM, measure resistance of FP PWR circuit between fuel
pump relay cavity and IFS switch harness connector. See Fig. 299-Fig. 304 . If resistance is less than 5
ohms, reinstall fuel pump relay and go to next step. If resistance is 5 ohms or more, repair open in FP
PWR circuit between IFS switch and FPM connection to circuit. See WIRING DIAGRAMS to
determine IFS switch splice location in circuit.

17) Check For Open Fuel Pump Ground Circuit

Disconnect fuel pump connector. Using a DVOM, measure resistance of fuel pump ground circuit
between chassis ground and fuel pump harness connector. See WIRING DIAGRAMS. If resistance is
less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in fuel pump ground circuit.

18) Check For Open FP PWR Circuit Between IFS Switch & Fuel Pump

Using a DVOM, measure resistance of FP PWR circuit between fuel pump harness connector and IFS
switch harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or
more, repair open in FP PWR circuit.

19) Check Internal Resistance Of Fuel Pump

Using a DVOM, measure resistance between FP PWR and ground circuits at fuel pump. If resistance is
10 ohms or more, replace fuel pump. If resistance is less than 10 ohms, all fuel pump circuits are okay.
Verify test results. If all test steps are okay, reconnect all components. Testing is complete. Disregard
DTC P0232 at this time. Repeat QUICK TEST and continue diagnostics as directed.

20) For KOEO & KOER Only DTC P0231: Attempt To Start Engine
If KOEO DTC P0230 is also present and has not been diagnosed, go directly to step 1) to check primary
fuel pump circuits. DTC P0231 indicates PCM commanded fuel pump ON and B+ voltage is not detected
on Fuel Pump Monitor (FPM) circuit. Possible causes are:

z

Open B+ circuit to fuel pump relay.

z

Open FP PWR circuit between fuel pump relay and connection to FPM circuit.

z

Faulty fuel pump relay.

z

Faulty PCM (Engine will start).

z

On F150 Lightning 5.4L SC, faulty Inertia Fuel Shutoff (IFS) switch, IFS switch relay, or concern
with related wiring.

Attempt to start engine. If engine starts, go to step 13). If engine does not start, verify IFS switch is set. If
switch is okay, go to next step.

21) Check B+ Voltage To Fuel Pump Relay

NOTE:

For additional testing information, see DIAGNOSTIC AIDS.

2003 Ford Pickup F150

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