Ford F150 Pickup. Instruction - part 1472

Fig. 186: Identifying Fuel Rail Pressure Sensor Circuits & Connector Terminals (Natural Gas Vehicles) 
Courtesy of FORD MOTOR CO. 

 

2003 Ford Pickup F150 

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

  

Fig. 187: Identifying Fuel Rail Pressure Sensor Circuits & Connector Terminals (Gasoline Vehicles) 
Courtesy of FORD MOTOR CO. 

TEST DF: VEHICLE SPEED CIRCUIT CHECK 

Diagnostic Aids 

Perform this test only when directed by QUICK TEST. This test is intended to diagnose the following:  

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Wiring Harness Circuits (VSC SIG & VSC GND).  

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Powertrain Control Module (PCM)  

Testing 

NOTE:

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 and DTCs are no longer present.

 

2003 Ford Pickup F150 

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

  

1) For Continuous Memory Only DTCs P0500, P0501 & P1502: Check Vehicle Speed PID 
DTCs P0500, P0501 and P1502 indicate that PCM has detected an error in vehicle speed information 
received from Vehicle Speed Sensor (VSS), Transfer Case Speed Sensor (TCSS) or Anti-Lock Brake 
System (ABS) module. Possible causes for this fault are: 

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Open or short in VSS (+) or VSS (-) circuit.  

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Open in TCSS signal or TCSS signal return circuit.  

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Short to GND in VSS or TCSS circuit.  

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Short to PWR in VSS or TCSS circuit.  

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Open or short in VSC between PCM and appropriate control module.  

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Faulty wheel speed sensor(s).  

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Faulty wheel speed sensor(s) wiring harness.  

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Faulty module(s) connected to vehicle speed circuit.  

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Faulty transfer case, vehicle or wheel speed sensors.  

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Faulty drive mechanism for VSS or TCSS.  

This test step checks for recurrence of this vehicle speed error. Turn ignition switch to ON position. 
Connect scan tool to Data Link Connector (DLC). Clear all DTCs. Obeying all local traffic laws, 
complete the following drive cycle:  

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Take the vehicle to a suitable location and gradually increase the vehicle speed to 50 MPH.  

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Coast down to an idle and stop the vehicle.  

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Shut the engine off.  

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After the drive cycle is completed, retrieve any Continuous Memory DTCs.  

If DTC P0500, P0501 or P1502 is present, turn ignition switch to OFF position. Vehicle speed input was 
not as expected, go to next step. If DTC P0500, P0501 or P1502 is not present, turn ignition off. Vehicle 
speed input was as expected, fault that produced original DTC may be intermittent. Go to step 5). 

2) Check VSC For Short To Power In Harness 
 
Turn ignition switch to OFF position. Disconnect PCM connector(s). Inspect connector for loose, 
damaged or corroded terminals. Repair as necessary. Disconnect appropriate control module. Turn 
ignition switch to ON position. Using a DVOM, measure voltage between negative battery terminal, and 
VSC GND, and VSC SIG at PCM harness connector. If both voltages are less than one volt, go to next 
step. If either voltage is one volt or more, go to step 6). 

3) Check For Open VSC Circuit Between PCM & ABS Control Module 

NOTE:

For additional testing information, see DIAGNOSTIC AIDS.

NOTE:

On most vehicles, DTC P0500 will cause Malfunction Indicator Light (MIL) 
to illuminate. When DTC P0501 is set, MIL will not be illuminated. When 
DTC P1502 is set, Transmission Control Indicator Light (TCIL) will flash 
with the first VSS circuit malfunction.

 

2003 Ford Pickup F150 

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

  

 
Turn ignition switch to OFF position. Using a DVOM, measure resistance of VSC SIG and VSC GND 
circuits between appropriate control module harness connector and PCM harness connector. If resistances 
are less than 5 ohms, go to next step. If either resistance is 5 ohms or more, repair open in affected circuit. 
After repair is complete, go to step 7) to perform VSC Repair Verification Drive Cycle. 

4) Check VSC Circuit For Short To Ground In Harness 
 
Disconnect scan tool from Data Link Connector (DLC). Using a DVOM, measure resistance between 
VSC SIG circuit, VSC GND circuit at PCM harness connector and chassis ground. If any resistance 
measurement is 10 k/ohms or less, go to step 6). If all resistance measurements are more than 10 k/ohms, 
check for fault in ABS control module, speed sensors and speed sensor circuits. See appropriate ANTI-
LOCK article in BRAKES. If no faults are present, replace PCM. After repair is complete, go to step 7) to 
perform VSC Repair Verification Drive Cycle. 

5) Visual Inspection 
 
Turn ignition switch to OFF position. Visually inspect vehicle speed circuit wiring harness for any of the 
following conditions: 

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Loose or corroded connector at appropriate control module.  

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Loose or corroded PCM harness connector.  

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Incorrect wiring harness routing of vehicle speed circuits.  

If any faults are present, repair as necessary. After repair is complete, go to step 7) to perform VSC 
Repair Verification Drive Cycle. If no concerns are found, fault is intermittent. Check for intermittent 
fault in appropriate ABS system. See appropriate ANTI-LOCK article in BRAKES. 

6) Check VSC Circuit For Short In Harness Or Another Module 
 
Determine if any other modules are connected to vehicle speed circuit. See WIRING DIAGRAMS. If no 
other modules are connected to vehicle speed circuit, repair short in vehicle speed circuit and go to next 
step. If other modules are connected to vehicle speed circuit, disconnect one module at a time that are 
associated with vehicle speed circuit. Repeat step 2) or 4) (depending on which step directed you here) to 
determine if short still exists in vehicle speed circuit. Repeat appropriate step until each associated 
module has been disconnected or short circuit has been eliminated. When short circuit disappears, 
diagnose appropriate module or related system causing short by determining appropriate article to 
diagnose specific module or system. See appropriate MODULE COMMUNICATIONS NETWORK 
article. If short circuit still exists with all associated modules disconnected, repair short in vehicle speed 
circuit and go to next step. 

7) VSC Repair Verification Drive Cycle 
 
Connect all disconnected components. Ensure engine is warmed to normal operating temperature. 
Perform the appropriate drive cycle 3 times: 

A/T Equipped Vehicles 

 

2003 Ford Pickup F150 

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