Ford F150 Pickup. Instruction - part 1565

both points, replace MFC (resistor) relay. Recheck cooling fan operation. 

137) Check Voltage To MFC (Resistor) Relay 
 
Ensure ignition switch is in OFF position. Reinstall LFC (fan braking) relay. Turn ignition switch to ON 
position. Using scan tool, command cooling fans on HIGH. Using a DVOM, measure voltage between 
chassis ground and MFC (resistor) relay cavity No. 30 (Light Green/Violet wire). If voltage is more than 
10 volts, reinstall MFC (resistor) relay and go to next step. If voltage is 10 volts or less, repair open in 
Light Green/Violet wire. Recheck cooling fan operation. 

138) Check Voltage To Driver's Side Cooling Fan 
 
Disconnect driver's side cooling fan connector. Using scan tool, command cooling fans on HIGH. Using a 
DVOM, measure voltage between chassis ground and driver side cooling fan harness connector terminal 
No. 3 (Red/Orange wire). See Fig. 331. If voltage is more than 10 volts, go to next step. If voltage is 10 
volts or less, repair open in Red/Orange wire. Recheck cooling fan operation. 

 

2003 Ford Pickup F150 

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

  

Fig. 331: Identifying Cooling Fan Harness Connector Terminals (Sable & Taurus) 
Courtesy of FORD MOTOR CO. 

139) Check Driver's Side Cooling Fan 
 
Connect a 40-amp fused jumper wire between positive battery terminal and driver's side cooling fan 
motor terminal No. 2 (Red/Orange wire), and another jumper wire between negative battery terminal and 
driver's side cooling fan motor terminal No. 1 (Black wire). If driver's side cooling fan operates, go to 
next step. If driver's side cooling fan does not operate, replace cooling fan motor. Recheck cooling fan 
operation. 

140) Check HCF No. 2 (HEDF) Relay 
 

 

2003 Ford Pickup F150 

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

  

Turn ignition switch to OFF position. Remove HCF No. 2 (HEDF) relay. See COOLING FAN RELAY 
LOCATIONS table. Using a DVOM, measure resistance between specified relay terminals. See MINI 
ISO RELAY RESISTANCE SPECIFICATIONS table. See Fig. 306. If relay resistance is not as 
specified, replace HCF No. 2 (HEDF) relay. If relay resistance is as specified, connect 2 jumper wires 
from positive battery terminal to relay terminals No. 30 and 85. Connect another jumper from relay 
terminal No. 86 to chassis ground. Using a DVOM, measure voltage between relay terminals No. 86 and 
87. Disconnect jumper from relay terminal No. 85 and measure voltage between relay terminals No. 86 
and 87a. If battery voltage is present at both points, go to next step. If battery voltage is not present at one 
or both points, replace HCF No. 2 (HEDF) relay. Recheck cooling fan operation. 

141) Check GND Circuit To Driver's Side Cooling Fan 
 
Reinstall HEDF relay. Using a DVOM, measure resistance between chassis ground and driver's side 
cooling fan harness connector terminal No. 1 (Black wire). If resistance is less than 5 ohms, go to next 
step. If resistance is 5 ohms or more, repair open in GND circuit. Recheck cooling fan operation. 

142) Check Voltage To Passenger's Side Cooling Fan 
 
Reconnect driver's side cooling fan connector, if previously disconnected. Disconnect passenger side 
cooling fan connector. Using scan tool, command cooling fans on HIGH and LOW. Using a DVOM, 
measure voltage between chassis ground and passenger side cooling fan harness side connector terminal 
No. 3 (Dark Blue wire). If voltage is 10 volts or less, repair open in Dark Blue wire between passenger's 
side cooling fan and splice No. 144, located in front right side of engine compartment. See WIRING 
DIAGRAMS. Recheck cooling fan operation. If voltage is more than 10 volts, proceed as follows: 

z

If voltage is more than 10 volts when cooling fans are commanded HIGH and LOW, go to step 
144).  

z

If voltage is more than 10 volts when cooling fans are commanded LOW only, go to next step.  

z

If voltage is more than 10 volts when cooling fans are commanded HIGH only, repair open in Dark 
Blue wire between HFC No. 2 (HEDF) relay and splice No. 144, located in front right side of 
engine compartment. See WIRING DIAGRAMS. Recheck cooling fan operation.  

143) Check EDF Relay 
 
Turn ignition switch to OFF position. Remove HCF No. 1 (EDF) relay. See COOLING FAN RELAY 
LOCATIONS table. Using a DVOM, measure resistance between specified relay terminals. See MINI 
ISO RELAY RESISTANCE SPECIFICATIONS table. See Fig. 306. If relay resistance is not as 
specified, replace HCF No. 1 (EDF) relay. If relay resistance is as specified, connect 2 jumper wires from 
positive battery terminal to relay terminals No. 30 and 85. Connect another jumper from relay terminal 
No. 86 to chassis ground. Using a DVOM, measure voltage between relay terminals No. 86 and 87. 
Disconnect jumper from relay terminal No. 85 and measure voltage between relay terminals No. 86 and 
87a. If battery voltage is not present at one or both points, replace HCF No. 1 (EDF) relay. Recheck 
cooling fan operation. If battery voltage is present at both points, repair open in Red/Orange wire between 
HFC No. 1 (EDF) relay and splice No. 144, located in front right side of engine compartment. See 
WIRING DIAGRAMS. Recheck cooling fan operation. 

144) Check Passenger's Side Cooling Fan GND Circuit 
 

 

2003 Ford Pickup F150 

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

  

Using a DVOM, measure resistance between chassis ground and passenger's side cooling fan harness 
connector terminal No. 1 (Black wire). If resistance is less than 5 ohms, replace passenger's side cooling 
fan. Recheck cooling fan operation. If resistance is 5 ohms or more, repair open in Black wire between 
passenger's side cooling fan and ground point G105, located in front of right front strut tower in engine 
compartment. Recheck cooling fan operation. 

145) Check Voltage To Cooling Fan Resistor 
 
Turn ignition switch to OFF position. Reinstall LFC (fan braking) relay and MFC (resistor) relay. Ensure 
ignition is in ON position. Disconnect cooling fan resistor. Located at harness stub out between cooling 
fans in right front of engine compartment. Using a DVOM, measure voltage between chassis ground and 
resistor harness connector terminal No. 1 (Dark Blue wire). If voltage is more than 10 volts, go to next 
step. If voltage is 10 volts or less, repair open in Dark Blue wire between MFC (resistor) relay. Recheck 
cooling fan operation. 

146) Check Red/Orange Wire To Driver's Side Cooling Fan For An Open 
 
Disconnect driver's side cooling fan connector. Using a DVOM, measure resistance of Red/Orange wire 
between cooling fan resistor harness connector terminal No. 2 and driver's side cooling fan harness 
connector. If resistance is less than 5 ohms, replace cooling fan resistor. Recheck cooling fan operation. If 
resistance is 5 ohms or more, repair open in Red/Orange wire between cooling fan resistor and driver's 
side cooling fan. Recheck cooling fan operation. 

151) Check A/C High Pressure Switch Input To PCM 
Turn ignition switch to ON position. Ensure A/C is off. Using scan tool, monitor ACP PID while ignition 
switch is turned to START position. If ACP PID indicates CLOSED, go to next step. If ACP PID does 
not indicate CLOSED, go to step 154). 

152) Check A/C High Pressure Switch 
 
Disconnect A/C high pressure switch connector. See A/C HIGH PRESSURE SWITCH LOCATIONS 
table. Turn ignition switch to ON position. Using scan tool, monitor ACP PID. If ACP PID indicates 
CLOSED, go to next step. If ACP PID does not indicate CLOSED, check A/C system for proper 
operation. Repair as necessary. See appropriate MANUAL or AUTOMATIC A/C-HEATER SYSTEMS 
article in AIR CONDITIONING & HEATING. If A/C system is okay, replace A/C high pressure switch. 
Recheck cooling fan operation. 

153) Check Black/Yellow Wire Between PCM and A/C High Pressure Switch For Short To Ground
 
Turn ignition switch to OFF position. Disconnect PCM connector. Using a DVOM, measure resistance 

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips 
from step 146) to step 151). No test procedures have been omitted.

NOTE:

This test step is performed with ignition switch in START position (engine 
cranking).

 

2003 Ford Pickup F150 

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