Ford F150 Pickup. Instruction - part 1372

Fig. 17: Identifying PCM Connector Circuit Functions (5 Of 5)
Courtesy of FORD MOTOR CO. 

SYSTEM TESTS 

HOW TO USE SYSTEM TESTS 

1. Ensure all non-EEC related faults found while performing basic diagnostic procedures in BASIC 

DIAGNOSTIC PROCEDURES - TRUCKS - EXCEPT DIESEL article have been corrected. Follow 
each test step in order until fault is found. DO NOT replace any part unless directed to do so. When more 
than one code is retrieved, start with first code displayed.  

2. System tests ensure electrical circuits are okay before sensors or other components are replaced. Always 

test circuits for continuity between sensor and PCM. Test all circuits for short to power, opens or short to 
ground. Voltage Reference (VREF) and Voltage Power (VPWR) circuits should be tested with ignition 
on or as specified in system test.  

3. If measuring voltage or resistance at PCM, always backprobe PCM connector. To identify PCM 

connector terminals, see Fig. 12 . DO NOT connect any test light unless specified in testing procedure. 
All measurements are made by probing rear of connector (wiring harness side). Isolate both ends of a 
circuit and turn ignition switch to OFF position when checking for shorts or continuity, unless instructed 
otherwise.  

4. Disconnect solenoids and switches from harness before measuring continuity and resistance or applying 

voltage. After each repair, check all component connections and repeat QUICK TEST .  

5. An open circuit is defined as a resistance reading of 5 ohms or more. This specification tolerance may be 

too high for some items in EEC-V system. If resistance approaches 5 ohms, always clean suspect 
connector and coat it with protective dielectric silicone grease. A short is defined as a resistance reading 
of 10,000 ohms or less to ground, unless stated otherwise in system test.  

6. If instructed to replace Powertrain Control Module (PCM) after performing a system test, new PCM must 

be programmed. See PROGRAMMING .  

CAUTION: Perform all resistance and voltage tests with a Digital Volt-Ohmmeter 

(DVOM) with minimum 10-megohm impedance, unless stated otherwise in 
test procedures. Ensure ignition switch is turned to OFF position when 
performing resistance tests.

NOTE:

For identification of circuits, components, terminals and wire colors referenced 
in the following testing, see ENGINE PERFORMANCE in appropriate SYSTEM 
WIRING DIAGRAMS article in ELECTRICAL. To prevent replacement of good 
components, be aware the following non-EEC related areas and components 
may be cause of problem: 

z

Fuel quality and quantity.  

z

Ignition (general condition).  

z

Engine mechanical components.  

z

Starter and battery circuits.  

 

2003 Ford Pickup F150 

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

  

TEST AA: NO START - GASOLINE AND ALTERNATE FUEL

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:  

z

AFCM  

z

Circuitry  

z

PCM  

PCM CONTROLLED INJECTOR DRIVER PINS 

Fig. 18: Identifying Fuel System Relay Circuits 
Courtesy of FORD MOTOR CO. 

Testing 

Injector No.

PCM Pin No.

AFCM Pin No.

1

75

61

2

101

62

3

74

63

4

100

64

5

73

65

6

99

66

7

72

67

8

98

68

NOTE:

Verify the Inertia Fuel Shutoff (IFS) switch is set (button pushed in). IFS switch 

 

2003 Ford Pickup F150 

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

  

1) Check The PCM For DTCs 
 

z

Key off.  

z

ALT fuel switch in GAS mode.  

z

Connect the scan tool.  

z

Key on, engine off.  

z

Access the PCM.  

z

Carry out the PCM self-tests.  

Are any PCM DTCs present? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-
DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article. If no, go to next step. 

2) Check The AFCM For DTCs 

z

Access the AFCM.  

z

Carry out the AFCM self-test.  

Are any AFCM DTCs present? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, 
go to next step. 

3) Check The Gasoline Relay For Voltage 

z

Key off.  

z

Disconnect the gasoline relay connector C1218.  

z

Key on, engine off.  

z

Access the PCM.  

z

Command the fuel pump on.  

z

Measure the voltage between the gasoline relay connector C1218 terminal No. 30, harness side and 
ground. See Fig. 11 .  

Is the voltage greater than 10 volts? If yes, go to step 5) . If no, go to next step. 

4) Check The PCM FUEL Pump Circuit 
 

z

Command the fuel pump off.  

z

Key off.  

z

Disconnect the PCM fuel pump relay connector C1051. 

is behind right kick panel.

NOTE:

For no communication with the AFCM, see TEST U: SCP INVALID OR 
MISSING DATA .

NOTE:

Gasoline relay may also be referred to as the fuel pump cut-off relay.

 

2003 Ford Pickup F150 

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

  

z

Measure the resistance between the PCM fuel pump relay connector C1051 terminal No. 87, 
harness side and the gasoline relay connector C1218, terminal No. 30 harness side. See Fig. 8 .  

Is the resistance less than 5 ohms? If yes, see SELF-DIAGNOSTICS - CNG, FLEX-FUEL & 
GASOLINE to continue diagnosis of the PCM fuel pump relay. If no, repair the circuit. 

5) Check The Gasoline Injector VPWR Circuit 
 

z

Command the fuel pump off.  

z

Key off. 

z

Disconnect two gasoline injectors.  

z

Key on, engine off.  

z

Measure the voltage between the right bank gasoline injector VPWR circuit, harness side and 
ground; and between the left bank gasoline injector VPWR circuit, harness side and ground.  

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

6) Check The Gasoline Injector Driver Circuit 

z

Connect a test lamp between the right bank gasoline injector VPWR circuit, harness side and the 
right bank gasoline injector driver circuit, harness side; and between the left bank gasoline injector 
VPWR circuit, harness side and the left bank gasoline injector driver circuit, harness side.  

z

Crank the engine.  

Does the test lamp blink consistently and brightly (one blink per engine revolution)? If yes, go to step 8) . 
If no, go to next step. 

7) Check The PCM Injector Driver Circuit 
 

z

Key off.  

z

Disconnect the AFCM connector C1427.  

z

Key on, engine off. 

z

Connect a test lamp between VPWR and the AFCM connector C1427 right bank injector driver 
circuit, harness side; and between VPWR and the AFCM connector C1427 left bank injector driver 
circuit, harness side. See CONNECTOR IDENTIFICATION . 

NOTE:

Check at least one fuel injector on each bank.

NOTE:

Check at least one fuel injector on each bank.

NOTE:

Check at least one fuel injector on each bank. See PCM 
CONTROLLED INJECTOR DRIVER PINS table.

 

2003 Ford Pickup F150 

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