Ford F150 Pickup. Instruction - part 1479

Turn ignition switch to ON position. Using scan tool, access CHT V PID from PID/DATA MONITOR & 
RECORD menu. If CHT V PID voltage is more than 4.6 volts, replace CHT sensor. For LS and 
Thunderbird, if CHT V PID voltage is 4.6 volts or less, go to step 22). For all others, go to next step. 

21) Check VREF Circuit Voltage At TP Sensor 
 
Disconnect TP sensor connector. Turn ignition switch to ON position. Using a DVOM, measure voltage 
between VREF and SIG RTN circuits at TP sensor harness connector. See Fig. 163-Fig. 166 . If voltage 
is 4-6 volts, VREF voltage is okay. Reconnect TP sensor and go to next step. If voltage is not 4-6 volts, 
go to TEST C, step 1). 

22) Check CHT Signal Circuit For Short To Ground 
 
Turn ignition switch to OFF position. Disconnect PCM connector(s). Inspect connector for loose, 
damaged or corroded terminals. Repair as necessary. Using a DVOM, measure resistance between CHT 
circuit, and PWR GND and SIG RTN circuits at PCM harness connector. See PCM PWR GND, SIG 
RTN & VREF TERMINAL IDENTIFICATION table. See PCM CONNECTOR 
IDENTIFICATION and Fig. 193 or Fig. 194 . If all resistance measurements are more than 10 k/ohms, 
replace PCM. If any resistance measurement is 10 k/ohms or less, repair short between circuits. 

30) For KOEO, KOER & Continuous Memory DTC P1285: Early Warning Of Engine Overheat 
Condition 
This DTC indicates that PCM sensed an engine overheat condition from CHT sensor. Possible causes for 
fault are: 

z

Low Engine Coolant Level  

z

Engine Mechanical Concern  

z

Engine Cooling System Concerns  

z

CHT Sensor Concern  

Check cooling system for external or internal leaks and restrictions. Check coolant level and cooling fan 
operation. Check for blockage in radiator. Repair as necessary. If electric cooling fan does not operate, 
see appropriate symptom under SYMPTOMS in TROUBLE SHOOTING - NO CODES - CNG, FLEX-
FUEL & GASOLINE article. If a cooling fan DTC is retrieved, see DIAGNOSTIC TROUBLE CODE 
DEFINITIONS. If cooling system is okay and no faults are found, check CHT sensor operation. Go to 
step 3). 

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips 
from step 22) to step 30). No test procedures have been omitted.

NOTE:

For additional testing information, see DIAGNOSTIC AIDS.

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips 
from step 30) to step 40). No test procedures have been omitted.

NOTE:

Diagnostic procedures beginning with step 40) are performed when 

 

2003 Ford Pickup F150 

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

  

40) Engine Temperature Warning Light Always On Or Temp Gauge Reads Hot, Engine Not 
Overheating 
If QUICK TEST was performed and no DTCs are present, go to next step. If QUICK TEST was not 
performed, perform QUICK TEST and service any DTCs that are present. 

41) Engine Temperature Warning Light Always On Or Temp Gauge Reads Hot (No DTCs) 
 
Engine Temperature Warning Indicator (gauge or lamp) is a warning system that gives driver information 
during an engine overheating condition. PCM monitors CHT sensor and determines if fail-safe cooling 
mode is needed. If fail-safe cooling is needed, PCM can signal driver in 2 ways: 

z

Temperature Warning Indicator Hard Wired To PCM 
 
PCM grounds engine temperature warning circuit when engine is overheating. This causes 
instrument cluster indicator to illuminate and/or forces temperature gauge to "H" (Hot) zone. A 
DTC P1285 will also be stored in PCM. 

z

Temperature Warning Indicator Information Received Through SCP 
 
PCM sends an SCP message to instrument cluster to signal an overheating condition. This causes 
instrument cluster indicator to illuminate and/or forces temperature gauge to "H" (Hot) zone. A 
DTC P1285 will also be stored in PCM. This test only diagnoses PCM hard wire systems with no 
cooling system DTCs stored.  

Possible causes are:  

z

Faulty ECT sensor.  

z

Faulty instrument cluster.  

z

Faulty wiring harness between PCM and instrument cluster.  

z

Faulty PCM.  

Disconnect PCM connector(s). Turn ignition switch to ON position. If engine temperature warning light 
is off, or temperature gauge measurement is in the normal zone, replace PCM. If engine temperature 
warning light is still illuminated, or temperature gauge measurement is in still in the "H" (Hot) zone, 
PCM is not the cause. Check instrument cluster and temperature warning light circuits. See appropriate 
INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT for diagnosis and testing. 

directed here from WARNING INDICATOR LIGHTS symptom under 
SYMPTOMS in TROUBLE SHOOTING - NO CODES - CNG, FLEX-FUEL & 
GASOLINE article.

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips 
from step 41) to step 80). No test procedures have been omitted.

NOTE:

For additional testing information, see DIAGNOSTIC AIDS.

 

2003 Ford Pickup F150 

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

  

80) For Continuous Memory Only DTC P0116: Check CHT Sensor Resistance With Engine Off 
DTC P0116 indicates CHT sensor drifted higher than normal sensor calibration curve and could prevent 
one or more OBD-II monitors from functioning. PCM will set DTC P0116 when all of the following 
conditions are met: 

z

Cylinder head temperature at engine start up exceeds IAT temperature by more than calibrated 
value, about 30°F (-1°C).  

z

Cylinder head temperature exceeds a calibrated value, about 225°F (107°C).  

z

Fuel, HO2S, catalyst and misfire monitors have not completed.  

z

Calibrated timer to set DTC P0116 has expired.  

Possible causes for this fault are:  

z

Faulty CHT Sensor  

z

Coolant System Fault  

Ensure engine temperature is at ambient room temperature. A soak period of 6 hours may be required. 
Turn ignition switch to OFF position. Disconnect CHT sensor connector. Using a DVOM, measure 
resistance between CHT sensor terminals. See CHT SENSOR SPECIFICATIONS table. If resistance is 
as specified, go to next step. If resistance is not as specified, replace CHT sensor. 

81) Check CHT Sensor Resistance With Engine Running 
 
Start engine and bring to operating temperature. Run at 2000 RPM for 2 minutes. Using a DVOM, 
measure resistance between CHT sensor terminals. See CHT SENSOR SPECIFICATIONS table. If 
resistance is not as specified, replace CHT sensor. If resistance is as specified, fault is not present at this 
time. Perform DRIVE CYCLES. Ensure OBD-II DRIVE CYCLE is performed to ensure Fuel, HO2S, 
Catalyst and Misfire monitors can be activated. 

90) For Continuous Memory Only DTC P0117, P0118, P1117, P1289 Or P1290: Intermittent Check
These DTCs indicate intermittent CHT sensor failure. Possible causes for these faults are: 

z

Open Or Grounded Circuit  

z

Faulty CHT Sensor  

z

Low Coolant Level  

z

Faulty PCM  

Connect scan tool to Data Link Connector (DLC). Turn ignition switch to ON position. Using scan tool, 
access CHT V PID from PID/DATA MONITOR & RECORD menu. While observing CHT V PID, 
lightly tap on CHT sensor and wiggle sensor connector to simulate road shock. A fault is indicated by a 
sudden change of CHT V PID temperature reading. If no fault is indicated, go to next step. If fault is 

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips 
from step 81) to step 90). No test procedures have been omitted.

NOTE:

For additional testing information, see DIAGNOSTIC AIDS.

 

2003 Ford Pickup F150 

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

  

indicated, turn ignition switch to OFF position. Disconnect and inspect connectors. If connectors are 
okay, replace CHT sensor. Clear DTCs and perform DRIVE CYCLE. Ensure OBD-II DRIVE CYCLE is 
performed to verify repair. 

91) Check EEC-V Wiring Harness 
 
Ensure CHT V PID is still selected. Starting at CHT sensor connector and working toward PCM, wiggle, 
shake and bend small sections of wiring harness. A fault is indicated by a sudden change of CHT V PID 
temperature reading. If no fault is indicated, go to next step. If fault is indicated, isolate and repair as 
necessary. Clear DTCs and perform DRIVE CYCLES. Ensure OBD-II DRIVE CYCLE is performed to 
verify repair. 

92) Check PCM & Wiring Harness 
 
Turn ignition switch to OFF position. Disconnect CHT sensor and PCM harness connectors. Inspect 
connectors for loose, damaged or corroded terminals. Repair as necessary. Perform DRIVE CYCLES. 
Ensure OBD-II DRIVE CYCLE is performed to verify repair. If connectors are okay, concern cannot be 
located at this time. Perform DRIVE CYCLES. Ensure OBD-II DRIVE CYCLE is performed to verify 
repair. 

100) For KOEO, KOER & Continuous Memory DTC P0217, & For KOER & Continuous Memory 
Only DTC P1299: Engine Overheat Condition Occurred 
These DTCs indicate an engine overheat condition was detected by CHT sensor and FMEM fail-safe 
cooling strategy was activated. On F150 Lightning 5.4L SC models, boost from supercharger will be by-
passed to avoid possible engine damage. Possible causes for this fault are: 

z

Cooling System Fault  

z

Low Coolant Level  

z

Engine Mechanical Fault  

Locate cooling system fault and repair as necessary. 

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips 
from step 92) to step 100). No test procedures have been omitted.

NOTE:

For additional testing information, see DIAGNOSTIC AIDS.

WARNING:

To avoid personal injury, DO NOT loosen coolant pressure relief cap 
while engine is operating or hot. Cooling system is under pressure 
and steam and/or hot coolant can come out forcefully when cap is 
loosened slightly.

NOTE:

For additional testing information, see DIAGNOSTIC AIDS.

WARNING:

To avoid personal injury, DO NOT loosen coolant pressure relief cap 

 

2003 Ford Pickup F150 

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