Ford F150 Pickup. Instruction — part 1377

2) Simulate An Opposite FRP Sensor Signal

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Key off.

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Disconnect the FRP sensor connector C106.

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Key on, engine off.

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Monitor the FRPREAB PID.

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Install a 5-amp fused jumper wire between the FRP sensor connector C106 signal circuit, harness
side and the FRP sensor connector C106 VREF circuit, harness side. See Fig. 23 .

Is the FRPREAB PID greater than 140 psi (965 kPa)? If yes, install a new FRP sensor. If no, go to next
step.

3) Check The FRP Sensor VREF And Signal Circuits For An Open

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Key off.

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Disconnect the AFCM connector C1427.

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Measure the resistance between the FRP sensor C106 VREF circuit, harness side and the AFCM
connector C1427 terminal No. 74, harness side. See CONNECTOR IDENTIFICATION .

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Measure the resistance between the FRP sensor connector C106 signal circuit, harness side and the
AFCM connector C1427 terminal No. 38, harness side.

Are the resistances less than 5 ohms? If yes, go to next step. If no, repair the circuit in question.

4) Check The FRP Sensor Signal Circuit For A Short To Ground

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Measure the resistance between the FRP sensor connector C106 signal circuit, harness side and
ground.

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Measure the resistance between the FRP sensor connector C106 VREF circuit, harness side and
ground.

Are the resistances less than 5 ohms? If yes, go to step 9) . If no, repair the circuit in question.

5) Simulate An Opposite Sensor Signal

z

Key off.

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Disconnect the FRP sensor connector C106.

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Key on, engine off.

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Monitor the FRPREAB PID.

Is the FRPREAB PID less than 5 psi (34 kPa)? If yes, go to step 8) . If no, go to next step.

6) Check The FRP Sensor Signal Circuit For A Short To VREF

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Key off.

2003 Ford Pickup F150

2003 ENGINE PERFORMANCE Self-Diagnostics - Bi-Fuel - Gasoline/CNG

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Disconnect the AFCM connector C1427.

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Measure the resistance between the FRP sensor connector C106 signal circuit, harness side and the
FRP connector C106 sensor VREF circuit, harness side. See Fig. 23 .

Is the resistance greater than 10,000 ohms? If yes, go to next step. If no, repair the circuit.

7) Check FRP Sensor Signal Circuit For A Short To Battery Voltage

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Key on, engine off.

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Measure the voltage between the FRP sensor connector C106 signal circuit, harness side and
ground.

Is any voltage indicated? If yes, repair the circuit. If no, go to step 9) .

8) Check The FRP Sensor SIG RTN Circuit For An Open

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Key off.

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Disconnect the AFCM connector C1427.

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Measure the resistance between the FRP sensor connector C106 SIG RTN circuit, harness side and
the AFCM connector C1427 terminal No. 74, harness side. See CONNECTOR
IDENTIFICATION .

Is the resistance less than 5 ohms? If yes, install a new FRP sensor. If no, repair the circuit.

9) Check For Correct AFCM Operation

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Disconnect the AFCM.

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Check for corrosion and pushed out pins.

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Connect the AFCM connector and make sure it is seated correctly.

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Operate the system and verify the concern is still present.

Is the concern still present? If yes, install a new AFCM. If no, the system is operating correctly at this
time. Concern may have been caused by a loose or corroded connector.

TEST H: FUEL CONTROL

Diagnostic Aids

Enter this test only when all steps under QUICK TEST have been successfully completed and engine still does
not start or if directed here from another test or chart. This test is only intended to diagnose:

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ALT Fuel Injectors

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AFCM

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Circuitry

2003 Ford Pickup F150

2003 ENGINE PERFORMANCE Self-Diagnostics - Bi-Fuel - Gasoline/CNG

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Gasoline Injectors

AFCM FUEL INJECTOR OUTPUTS

Testing

1) Access The AFCM DTCs

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Key off.

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Connect the scan tool.

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Key on, engine off.

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Access the AFCM.

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Carry out the AFCM self-test.

Are any AFCM DTCs present? If yes, for DTCs P1271 through 1278 and P0262, P0265, P0268, P0271,
P0274, P0277, P0280 or P0283, go to next step. For DTCs P1261 through 1268 and P0261, P0264,
P0267, P0270, P0273, P0276, P0279 or P0282, go to step 3) . If no, go to step 6) .

2) Check The Fuel Injector Driver Circuit(s) For A Short To Voltage

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Key off.

NOTE:

During bi-fuel diagnostics, intermittent failures are possible. Perform wiggle
test and tap lightly on relays during testing. Ensure vehicle has CNG before
continuing with diagnostics.

Circuit

AFCM Pin No.

Gasoline Inj. No. 1

76

Gasoline Inj. No. 2

77

Gasoline Inj. No. 3

78

Gasoline Inj. No. 4

79

Gasoline Inj. No. 5

80

Gasoline Inj. No. 6

81

Gasoline Inj. No. 7

82

Gasoline Inj. No. 8

83

ALT Fuel Inj. No. 1

46

ALT Fuel Inj. No. 2

47

ALT Fuel Inj. No. 3

48

ALT Fuel Inj. No. 4

49

ALT Fuel Inj. No. 5

50

ALT Fuel Inj. No. 6

51

ALT Fuel Inj. No. 7

52

ALT Fuel Inj. No. 8

53

2003 Ford Pickup F150

2003 ENGINE PERFORMANCE Self-Diagnostics - Bi-Fuel - Gasoline/CNG

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Disconnect the suspect injector.

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Disconnect the AFCM connector C1427.

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Key on, engine off.

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Measure the voltage between the suspect fuel injector driver circuit, harness side and ground. See
CONNECTOR IDENTIFICATION .

Is any voltage indicated? If yes, repair the circuit in question. If yes, go to step 5) .

3) Check The Fuel Injector VPWR Circuit(s) For Voltage

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Key off.

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Disconnect the suspect injector.

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Key on, engine off.

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Measure the voltage between the suspect fuel injector VPWR circuit, harness side and ground.

Is the voltage greater than 10 volts? If yes, go to next step. If no, repair the circuit in question.

4) Check The Fuel Injector Driver Circuit(s) For An Open And A Short To Ground

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Key off.

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Disconnect the AFCM connector C1427.

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Measure the resistance between the suspect fuel injector driver circuit, harness side and the AFCM
connector C1427 injector driver circuit, harness side; and between the suspect fuel injector driver
circuit, harness side and ground. See AFCM FUEL INJECTOR OUTPUTS table. See
CONNECTOR IDENTIFICATION .

Is the resistance less than 5 ohms between the suspect fuel injector and the AFCM; and is the resistance
greater than 10,000 ohms between the suspect fuel injector and ground? If yes, go to next step. If no,
repair the circuit in question.

5) Check The Fuel Injector(s) Resistance

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Key off.

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Measure the resistance between the suspect fuel injector VPWR circuit, component side and the
suspect fuel injector driver circuit, component side.

Is the resistance between 11.0 and 18.0 ohms for the gasoline injectors; and is the resistance between 2.0
and 15.0 ohms for ALT fuel injectors? If yes, go to step 10) . If no, install a new fuel injector.

6) Check The PCM For DTCs

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Access the PCM.

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Carry out the PCM self-tests.

2003 Ford Pickup F150

2003 ENGINE PERFORMANCE Self-Diagnostics - Bi-Fuel - Gasoline/CNG