Ford F150 Pickup. Manual — 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