Ford F150 Pickup. Manual - part 1462

25) Check SIG RTN/PWR GND Through PCM On TP PID 
 
Turn ignition switch to ON position. Connect scan tool to Data Link Connector (DLC). Using scan tool, 
access PID/DATA MONITOR & RECORD menu. See PARAMETER IDENTIFICATION MODE 
under ADDITIONAL SYSTEM FUNCTIONS. Using scan tool, access TP PID from PID/DATA 
MONITOR & RECORD menu. If scan tool is able to access TP PID, go to next step. If scan tool is 
unable to access TP PID, go to step 28). 

26) Check For KOEO DTCs Present For 2 Or More Sensors/Switches Connected To SIG/RTN 
Circuit 
 
If KOEO DTCs are present for 2 or more sensors connected to SIG RTN circuit, go to next step. If KOEO 
DTCs are present for only one sensor, repair open in SIG RTN circuit to sensor where VREF check 
failed. See WIRING DIAGRAMS. 

27) Check SIG RTN Circuit For Open In Harness 
 
Turn ignition switch to OFF position. Disconnect scan tool from Data Link Connector (DLC). Disconnect 
sensor where VREF check failed. Disconnect PCM connector(s). Inspect connector for damage and repair 
as necessary. Using a DVOM, measure resistance of SIG/RTN circuit between PCM harness connector 
and suspect sensor harness connector. See WIRING DIAGRAMS. If resistance is less than 5 ohms, 
reconnect sensor and go to next step. If resistance is 5 ohms or more, repair open in SIG RTN circuit. 

28) Check PCM PWR GND Circuits For Open To PCM 
 
Turn ignition switch to OFF position. Disconnect scan tool from DLC. Using a DVOM, measure 
resistance of PWR GND circuits between negative battery terminal and specified PCM harness connector 
terminals. Refer to PCM PWR GND, SIG RTN & VREF TERMINAL IDENTIFICATION table. If 
all resistance measurements are less than 5 ohms, go to next step. If any resistance measurement is 5 
ohms or more, repair open in affected PWR GND circuit. 

29) Check Ground Circuits For Open In PCM 
 
Leave ignition switch turned to OFF position and scan tool and PCM disconnected. Using a DVOM, 
measure resistance between specified PCM SIG RTN and PWR GND terminals (component side). Refer 
to PCM PWR GND, SIG RTN & VREF TERMINAL IDENTIFICATION table. If all resistance 
measurements are less than 5 ohms, PWR GND and SIG RTN circuits are okay inside PCM. Verify 
results from previous test steps. Repeat QUICK TEST. If any resistance measurement is 5 ohms or more, 
replace PCM. 

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips 
from step 20) to step 25). No test procedures have been omitted.

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips 
from step 29) to step 35). No test procedures have been omitted.

 

2003 Ford Pickup F150 

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

  

35) Check VREF Circuit For Short To PWR 
 
Turn ignition switch to OFF position. Ensure sensor is disconnected where VREF check failed. 
Disconnect all other sensors connected to VREF circuit. See SENSORS CONNECTED TO VREF 
CIRCUIT table. Disconnect PCM connector(s). Turn ignition switch to ON position. Using a DVOM, 
measure voltage between negative battery terminal and VREF terminal at TP sensor harness connector. If 
voltage is less than .5 volt, turn ignition switch to OFF position and replace PCM. If voltage is .5 volt or 
more, turn ignition switch to OFF position and repair VREF circuit for a short to PWR. 

SENSORS CONNECTED TO VREF CIRCUIT 

Application

Sensors Connected To VREF

Circuit

Aviator

TP, ESM, FTP, FRP

Crown Victoria (Except NGV), Grand Marquis & Marauder

TP, DPFE, FTP, FRP, PSP, ACP

Crown Victoria (NGV)

TP, DPFE, FRP, PSP, ACP

"E" Series 5.4L (NGV)

TP, FRP

Blackwood, & "E" & "F" Series 4.2L, 4.6L & 5.4L (Except 
NGV)

TP, DPFE, FTP

"E" & "F" Series 6.8L

TP, FTP

Escape

TP, DPFE, FTP

Expedition & Navigator

TP, DPFE, FTP, PSP

Explorer, Explorer Sport, Explorer Sport Trac & Mountaineer

TP, DPFE, FTP

"F" Series 4.2L & 4.6L

TP, ESM, FTP, PSP

"F" Series 5.4L (NGV)

TP, ICP

Focus

DURATEC

TP, FRP, FTP, BAP

SPI & ZETEC

TP, FRP, FTP, EPT

PZEV

TP,FRP, FTP, IMAP, IMRC, PSP

Lightning 5.4L SC

TP, DPFE, FTP, BAP

LS & Thunderbird

EAT, FTP, FRP, ACP

Mustang

Cobra

TP, DPFE, FTP, FRP, BAP

3.8L, 4.6L (2V) & Mach 1

TP, DPFE, FTP, FRP

Ranger

2.3L

TP, MAP, FTP, SCVM

3.0L & 4.0L

TP, FTP

Sable & Taurus

3.0L (2V)

TP, DPFE, FTP, FRP

3.0L (4V)

TP, DPFE, FTP, FRP, PSP

Town Car

TP, DPFE, FTP, ACP, PSP, FRP

Windstar

ACP, DPFE, FTP, TP

ZX2

TP, FTP, PSP, FRP

 

2003 Ford Pickup F150 

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

  

TEST DA: TEMPERATURE SENSOR TEST (IAT, ECT & EOT)

Diagnostic Aids 

Perform this test only when directed by QUICK TEST. Engine coolant temperature and engine oil temperature 
must be more than 50°F (10°C) to pass KOEO SELF-TEST and more than 180°F (82°C) to pass KOER SELF-
TEST. Ambient air temperature must be at least 50°F (10°C) to receive valid input from Intake Air Temperature 
(IAT) sensor. Engine oil temperature must be more than 50°F (10°C) to pass KOEO SELF-TEST and more than 
180°F (82°C) to pass KOER SELF-TEST. Voltage values in this test are based on a 5-volt VREF signal. Values 
may vary up to 15 percent due to sensor and VREF variations. 

This system test is intended to diagnose the following components and circuits:  

z

Intake Air Temperature (IAT) Sensor Or Integrated Intake Air Temperature (IAT) Sensor  

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MAF With Integrated Intake Air Temperature (IAT) Sensor.  

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Engine Coolant Temperature (ECT) Or Cylinder Head Temperature (CHT) Sensor  

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Engine Oil Temperature (EOT) Sensor  

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Wiring Harness Circuits (IAT, ECT, EOT & SIG RTN)  

z

Powertrain Control Module (PCM)  

To prevent replacing good components, ensure the following non-EEC areas or components are not cause of 
concern:  

z

Coolant Level Low  

z

Cooling System, Water Pump Or Fan  

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Engine Operating Temperature  

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Engine Oil Level Low  

z

Thermostat  

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Air Cleaner Duct  

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Ambient Temperature  

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.

NOTE:

On some models, IAT sensor is part of Mass Airflow (MAF) sensor assembly. If 
all 6 terminals of MAF sensor connector are being used, IAT sensor is integral 
to MAF sensor. See WIRING DIAGRAMS.

NOTE:

For additional testing information, see DIAGNOSTIC AIDS.

 

2003 Ford Pickup F150 

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

  

1) For KOEO & KOER Only DTC P1116: Check Operation Of ECT Sensor 
This DTC indicates sensor is out of self-test range. Correct range for measurement is .3-3.7 volts. Check 
for following possible causes: 

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Overheating Condition  

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Malfunctioning Thermostat  

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Faulty ECT Sensor  

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Low Coolant Level  

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Faulty Harness Or Connector  

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Faulty PCM  

If directed here because engine is a no-start, go to step 3). If vehicle has a stalling concern, go to 
appropriate symptom under SYMPTOMS in TROUBLE SHOOTING - NO CODES - CNG, FLEX-
FUEL & GASOLINE article. Start and run engine at 2000 RPM until engine reaches normal operating 
temperature. Ensure upper radiator hose is hot and pressurized. Repeat KOER ON-DEMAND SELF-
TEST. If DTC P1116 is present, go to next step. If DTC P1116 is not present, engine was not at closed 
loop operating conditions when KOER ON-DEMAND SELF-TEST was performed. Repair any other 
DTCs that are present. 

2) Check VREF Circuit Voltage To TP Sensor 
 
Turn ignition switch to OFF position. Disconnect Throttle Position (TP) sensor. Turn ignition switch to 
ON position. Using a DVOM, measure voltage between VREF and SIG RTN terminals at TP sensor 
harness connector. See Fig. 163-Fig. 166 . If voltage is 4-6 volts, reconnect TP sensor and go to next step. 
If voltage is not 4-6 volts, go to TEST C, step 1). 

3) Check ECT Sensor Resistance With Engine Off 
 
Turn ignition switch to OFF position. Disconnect ECT sensor. Using a DVOM, measure resistance 
between ECT sensor SIG and SIG RTN circuit terminals. See Fig. 171. Compare sensor resistance to 
appropriate temperature specification in illustration. See Fig. 177. If resistance is not as specified, replace 
faulty ECT sensor. If resistance is as specified, perform following step as applicable: 

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For diagnosing vehicles with an ECT sensor related fault, or engine is a no-start, DO NOT service 
DTC P1116 at this time. See NO START/NORMAL CRANK symptom under SYMPTOMS in 
TROUBLE SHOOTING - NO CODES - CNG, FLEX-FUEL & GASOLINE article.  

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For diagnosing vehicles with cooling fan concerns or engine cooling concerns, DO NOT service 
DTC P1116 at this time. Service next DTC. If no other DTCs are present, repair by symptom. See 
SYMPTOMS in TROUBLE SHOOTING - NO CODES - CNG, FLEX-FUEL & GASOLINE 
article.  

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For vehicles with no other fault conditions or DTCs, go to next step. 

 

2003 Ford Pickup F150 

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