Ford F150 Pickup. Instruction — part 1539

Turn ignition switch to OFF position. Disconnect PCM connector(s). Inspect connector for loose,
damaged or corroded terminals. Repair as necessary. Using a DVOM, measure resistance of suspect CD
circuit between PCM harness connector and appropriate coil-on-plug harness connector. Refer to
IGNITION COIL-TO-CYLINDER CORRELATION (COIL-ON-PLUG) table to determine PCM
terminal number. See Fig. 297 or Fig. 298 . If resistance is less than 5 ohms, go to next step. If resistance
is 5 ohms or more, repair open in CD circuit.

6) Check Suspect CD Circuit For Short To VPWR In Harness

Turn ignition switch to ON position. Using a DVOM, measure voltage between chassis ground and
suspect CD circuit at PCM harness connector terminal. Refer to IGNITION COIL-TO-CYLINDER
CORRELATION (COIL-ON-PLUG) table to determine PCM terminal number. If voltage is less than
one volt, go to next step. If voltage is one volt or more, repair CD circuit for short to VPWR.

7) Check Suspect CD Circuit For Short To Ground In Harness

Turn ignition switch to OFF position. Disconnect scan tool from DLC. Using a DVOM, measure
resistance of suspect CD circuit between chassis ground and PCM harness connector. Refer to
IGNITION COIL-TO-CYLINDER CORRELATION (COIL-ON-PLUG) table to determine PCM
terminal number. If resistance is more than 10 k/ohms, replace PCM. If symptom or DTC still exists after
replacing PCM, go to next step to check for damaged coil. If resistance is 10 k/ohms or less, repair short
to ground in CD circuit. If symptom or DTC still exists after repair is complete, go to next step to check
for damaged coil.

8) Check Suspect Coil For Damage

Remove suspect coil from spark plug. Refer to IGNITION COIL-TO-CYLINDER CORRELATION
(COIL-ON-PLUG) table to determine suspect coil. Install Air Gap Spark Tester (303-D037) to suspect
coil. Reconnect coil harness connector. Observe spark tester while cranking engine. If spark is not
present, replace coil. Inspect spark plug and replace as necessary. If spark is present, check spark plug.
Replace as necessary and retest. If spark plug is okay, no fault is present at this time. Go to TEST Z, step
1).

TEST JH: TACHOMETER OUTPUT FAILURE

Diagnostic Aids

Perform this test when instructed to or if directed by other test procedures. This test is used to diagnose the
PCM.

Testing

NOTE:

Applies only to models with Clean Tachometer Output (CTO) circuit from
Powertrain Control Module (PCM) connector terminal No. 48. After each service
or repair procedure has been completed, reconnect all components. Clear DTCs
and repeat QUICK TEST procedures to ensure all EEC-V systems are working
properly.

2003 Ford Pickup F150

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

1) Check CTO Circuit For Short To VPWR In Harness

Turn ignition switch to OFF position. Disconnect PCM connector. Inspect connector for loose, damaged
or corroded terminals. Turn ignition switch to ON position. Using a DVOM, measure voltage between
chassis ground and PCM harness connector terminal No. 48. See PCM CONNECTOR
IDENTIFICATION. If voltage is less than .5 volt, go to next step. If voltage is .5 volt or more, repair
short to VPWR in CTO circuit.

2) Check CTO Circuit For Short To Ground In Harness

Turn ignition switch to OFF position. Disconnect instrument cluster connector. Using a DVOM, measure
resistance between PCM harness connector terminal No. 48, chassis ground and negative battery terminal.
If both resistance measurements are more than 10 k/ohms, go to next step. If either resistance
measurement is 10 k/ohms or less, repair short to ground in CTO circuit.

3) Check CTO Circuit For Open In Harness

Using a DVOM, measure resistance of CTO circuit between PCM harness connector terminal No. 48 and
instrument cluster 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 CTO circuit.

4) Check CTO Signal From PCM

Reconnect PCM harness connector. Start engine. Using a DVOM, measure voltage between CTO circuit
at instrument cluster harness connector and negative battery terminal. If voltage is not 3-9 volts, replace
PCM. If voltage is 3-9 volts, CTO signal from PCM is okay. Check instrument cluster and repair as
necessary. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT.

TEST KA: FUEL PUMP RELAY

Diagnostic Aids

Perform this test when instructed during QUICK TEST or if directed by other test procedures. This test is used
to diagnose the following:

z

Fuel Pump Relay

z

Inertia Fuel Shutoff (IFS) Switch

z

Wiring Harness Circuits (B+, FP, FPM, FP PWR, GND, LFP & VPWR)

z

Powertrain Control Module (PCM)

NOTE:

For fuel pump relay testing on Focus, LS, Mustang, Sable, Taurus, Thunderbird
and ZX2, see TEST KB: FUEL PUMP DRIVER MODULE (FPDM). For fuel pump
relay testing on Natural Gas Vehicles (NGV), see TEST KC: FUEL SHUTOFF
VALVE RELAY.

2003 Ford Pickup F150

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

Fig. 299: Identifying Fuel System Circuits (Blackwood, Econoline, Escape, F150 - Except F150 Lightning
5.4L SC)
Courtesy of FORD MOTOR CO.

2003 Ford Pickup F150

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

Fig. 300: Identifying Fuel System Circuits (Explorer & Mountaineer)
Courtesy of FORD MOTOR CO.

2003 Ford Pickup F150

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