Ford F150 Pickup. Instruction - part 1340

2003 ENGINE PERFORMANCE

System & Component Testing - Bi-Fuel - Gasoline/LPG 

INTRODUCTION 

COMPUTERIZED ENGINE CONTROLS 

POWERTRAIN CONTROL MODULE 

Ground Circuits 

Turn ignition off. Disconnect PCM 104-pin connector. PCM is located on right rear of engine compartment. 
Using DVOM, check for continuity between chassis ground and PCM harness connector terminals No. 3, 25, 
51, 76 and 103. See Fig. 1 . If continuity exists, see POWER CIRCUITS . If continuity does not exist, repair 
open in affected ground circuit. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in 
ELECTRICAL. 

Power Circuits 

WARNING:

Before performing any tests or diagnostics on LPG components or 
systems, read all cautions and warnings in LPG SAFETY PRECAUTIONS 
article in GENERAL INFORMATION.

NOTE:

System and component testing included in this article is for alternative fuel 
systems only. For gasoline fuel system and component testing, see SYSTEM & 
COMPONENT TESTING - GASOLINE article. Since many computer-controlled 
and monitored components set a Diagnostic Trouble Code (DTC) when a 
malfunction occurs, check for Powertrain Control Module (PCM) DTCs and 
Alternative Fuel Control Module (AFCM) DTCs prior to testing an individual 
system or component. Perform QUICK TEST procedures in SELF-DIAGNOSTICS 
- CNG, FLEX-FUEL & GASOLINE article, or QUICK TEST procedures in SELF-
DIAGNOSTICS - BI-FUEL - GASOLINE/LPG article. If no DTCs are present, 
perform SYMPTOM DIAGNOSIS under SYMPTOMS in TROUBLE SHOOTING - 
NO CODES - BI-FUEL - GASOLINE/LPG article to diagnose driveability problems 
existing when a hard fault code is not present. For specifications, see 
appropriate ON-VEHICLE ADJUSTMENTS - TRUCKS or appropriate SERVICE & 
ADJUSTMENT SPECIFICATIONS article.

NOTE:

Testing individual components does not isolate short or open circuits. Perform 
all voltage tests with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-
megohm input impedance, unless stated otherwise in test procedure. Use 
ohmmeter to isolate shorted or open wiring harness. For identification of 
circuits and terminals referenced in test procedures, see ENGINE 
PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE System & Component Testing - Bi-Fuel - Gasoline/LPG

  

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE System & Component Testing - Bi-Fuel - Gasoline/LPG

  

1. Ensure ignition is off. Using DVOM, check for battery voltage between chassis ground and PCM Keep 

Alive Memory Power (KAPWR) terminal No. 55. See Fig. 1 . If battery voltage is present, go to next 
step. If battery voltage is not present, check for open in KAPWR circuit or fuse No. 2 (5-amp), located in 
central junction box. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in 
ELECTRICAL.  

2. Turn ignition on. Using DVOM, check for battery voltage between chassis ground and VPWR at PCM 

connector terminals No. 71 and 97. If battery voltage is not present, power is not being supplied from 
PCM power relay. See TEST B: EEC-V POWER RELAY under SYSTEM TESTS in SELF-
DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article.  

Fig. 1: Identifying Powertrain Control Module Connector Terminals 
Courtesy of FORD MOTOR CO. 

ALTERNATIVE FUEL CONTROL MODULE 

Ground Circuits 

Turn ignition off. Disconnect compuvalve 64-pin connector. Compuvalve is located in right rear corner of 
engine compartment. Using DVOM, check for continuity between chassis ground and compuvalve connector 
terminals No. 57, 59, 61, 62, 63 and 64. See Fig. 2 . If continuity exists, go to next step. If continuity does not 
exist, repair open in affected ground circuit. See ENGINE PERFORMANCE in SYSTEM WIRING 
DIAGRAMS article in ELECTRICAL. 

Fig. 2: Identifying Compuvalve Connector C1294 Terminals 
Courtesy of FORD MOTOR CO. 

Power Circuits 

Turn ignition off. Ensure compuvalve 64-pin connector is disconnected. Turn ignition on. Using DVOM, check 
for battery voltage between chassis ground and compuvalve VPWR terminals No. 2, 11 and 13. See Fig. 2 . If 

NOTE:

Alternative Fuel Control Module (AFCM) is contained within compuvalve 
assembly. AFCM is only used on bi-fuel vehicles.

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE System & Component Testing - Bi-Fuel - Gasoline/LPG

  

battery voltage is not present, power is not being supplied from bi-fuel relay module. Repair open in affected 
circuit or bi-fuel relay module as necessary. See ENGINE PERFORMANCE in SYSTEM WIRING 
DIAGRAMS article in ELECTRICAL. 

ENGINE SENSORS & SWITCHES 

SENSORS 

Fuel Rail Pressure Sensor 

Faults in Fuel Rail Pressure (FRP) sensor or circuit should set a Diagnostic Trouble Code (DTC). Perform 
QUICK TEST in SELF-DIAGNOSTICS - BI-FUEL - GASOLINE/LPG article. If no DTC has been set, go to 
TEST DC: FUEL RAIL PRESSURE under SYSTEM TESTS in SELF-DIAGNOSTICS - BI-FUEL - 
GASOLINE/LPG article for FRP sensor and circuit testing. 

Fuel Rail Temperature Sensor 

Faults in Fuel Rail Temperature (FRT) sensor or circuit should set a Diagnostic Trouble Code (DTC). Perform 
QUICK TEST in SELF-DIAGNOSTICS - BI-FUEL - GASOLINE/LPG article. If no DTC has been set, see 
TEST DA: FUEL RAIL TEMPERATURE under SYSTEM TESTS in SELF-DIAGNOSTICS - BI-FUEL - 
GASOLINE/LPG article for FRT sensor and circuit testing. 

Heated Oxygen Sensor 

Faults in Heated Oxygen Sensor (HO2S) or circuit should set a Diagnostic Trouble Code (DTC). Perform 
TEST H: FUEL CONTROL in SELF-DIAGNOSTICS - BI-FUEL - GASOLINE/LPG article. 

Manifold Absolute Pressure Sensor 

Faults in Manifold Absolute Pressure (MAP) sensor or circuit should set a Diagnostic Trouble Code (DTC). 
Perform QUICK TEST in SELF-DIAGNOSTICS - BI-FUEL - GASOLINE/LPG article. If no DTC has been 
set, see TEST DB: MAP/BARO SENSOR under SYSTEM TESTS in SELF-DIAGNOSTICS - BI-FUEL - 
GASOLINE/LPG article for MAP sensor and circuit testing. 

Reference Voltage 

Faults in sensor reference voltage or signal return circuits should set a DTC. Perform QUICK TEST in SELF-
DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article. If no DTC has been set, see TEST C: 
REFERENCE VOLTAGE under SYSTEM TESTS in SELF-DIAGNOSTICS - CNG, FLEX-FUEL & 
GASOLINE article for sensor reference voltage and signal return circuit testing. 

SWITCHES 

ALT Fuel Switch 

NOTE:

For additional gasoline-related sensor testing procedures, see SYSTEM & 
COMPONENT TESTING - GASOLINE article.

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE System & Component Testing - Bi-Fuel - Gasoline/LPG

  

For ALT fuel switch or circuit testing, repair by symptom. See SYMPTOM DIAGNOSIS under SYMPTOMS 
in TROUBLE SHOOTING - NO CODES - BI-FUEL - GASOLINE/LPG article. 

Inertia Fuel Shutoff Switch 

Turn ignition off. Locate Inertia Fuel Shutoff (IFS) switch, behind right kick panel. Shake or jar IFS switch to 
cause switch to open. IFS switch reset button should pop up. Fuel pump should not operate and vehicle should 
not start. Push down on reset button. Restart engine. Fuel pump should operate. 

RELAYS & SOLENOIDS 

RELAYS 

Bi-Fuel Relay Module 

Perform QUICK TEST in SELF-DIAGNOSTICS - BI-FUEL - GASOLINE/LPG article. If no DTC has been 
set, repair by symptom. See SYMPTOM DIAGNOSIS under SYMPTOMS in TROUBLE SHOOTING - NO 
CODES - BI-FUEL - GASOLINE/LPG article 

FUEL SYSTEM SAFETY PRECAUTIONS 

BI-FUEL SYSTEM 

Liquefied Petroleum Gas 

Avoid inhaling Liquefied Petroleum Gas (LPG) or occupying confined areas containing LPG. LPG (propane) is 

NOTE:

If a fault exists in bi-fuel relay module, an AFCM DTC or driveability concern 
should be present.

CAUTION: Natural gas in fuel system is at high pressure at all times. To avoid injury 

or fire, release fuel pressure from fuel system before disassembling any 
fuel system component. To release fuel system pressure, follow pressure 
relief procedure. See FUEL SYSTEM PRESSURE RELEASE under FUEL 
SYSTEMS in REMOVAL & INSTALLATION - F150 PICKUP - BI-FUEL - 
GASOLINE/LPG article. After performing fuel system pressure relief 
procedure, a small amount of pressure 3 psi (21 kPa) will remain in fuel 
rail, and high pressure still exists in fuel tanks. Prevent combustion from 
escaping fuel; no smoking, open flames or any kind of arcing.

WARNING:

Use care to prevent combustion from fuel spillage. No smoking, open 
flames or any kind of arcing.

NOTE:

Liquefied Petroleum Gas (LPG) may also be referred to as propane. Propane is 
heavier than air.

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE System & Component Testing - Bi-Fuel - Gasoline/LPG