Ford F150 Pickup. Manual — part 1561

34) Check For Open HIGH FAN PWR & LOW FAN PWR Circuits

Using a DVOM, measure resistance of HIGH FAN PWR and LOW FAN PWR circuits between
appropriate HFC or LFC relay cavity and appropriate cooling fan harness connector. See Fig. 321, Fig.
325-Fig. 327 or Fig. 329 . If both resistance measurements are less than 5 ohms, go to next step. If either
resistance measurement is 5 ohms or more, locate and repair open in affected circuit. Recheck cooling fan
operation.

35) Command Low Speed Fan ON & Check For Voltage To Cooling Fans

Reinstall HFC and LFC relays. Ensure cooling fan connector(s) are disconnected. Turn ignition switch to
ON position. Using scan tool, access OUTPUT TEST MODE. Command low speed fan ON. Using a
DVOM, measure voltage between negative battery terminal and LOW FAN PWR circuit at cooling fan
harness connector (either connector on models with 2 cooling fans). See Fig. 321-Fig. 327 or Fig. 329 . If
voltage is more than 10 volts, replace HFC relay and go to step 37). If voltage is 10 volts or less, go to
step 75) and follow procedure for low speed cooling fan inoperative. After repair, repeat step 75) and
follow procedure for high speed cooling fan inoperative.

37) Check Cooling Fan Ground Circuit

Turn ignition switch to OFF position. Disconnect scan tool from DLC. Using a DVOM, measure
resistance of GND circuit between negative battery terminal and cooling fan harness connector(s). If
resistance is less than 5 ohms, replace inoperative cooling fan(s). If resistance is 5 ohms or more, locate
and repair open in GND circuit. Recheck cooling fan operation.

40) Determine Which Fan Speed Is Operational

If high speed fan was inoperative in step 31), go to step 46). If low speed fan was inoperative in step 31),
go to next step.

41) Low Speed Fan Inoperative: Command Low Fan ON & Check Voltage To Cooling Fan

Ensure ignition switch is in ON position, scan tool is in OUTPUT TEST MODE and low speed cooling
fan commanded OFF. Disconnect appropriate cooling fan connector (both connectors on models with 2
cooling fans). Using scan tool, command low speed fan ON. Using a DVOM, measure voltage between
negative battery terminal and LOW FAN PWR circuit at appropriate cooling fan harness connector. See
Fig. 321-Fig. 329 . If voltage is 10 volts or less, go to next step. If voltage is more than 10 volts, check
GND circuit to appropriate cooling fan. If GND circuit is okay, replace cooling fan and recheck cooling
fan operation.

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips
from step 35) to step 37). No test procedures have been omitted.

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips
from step 37) to step 40). No test procedures have been omitted.

2003 Ford Pickup F150

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

42) Check B+ Voltage To LFC Relay

Turn ignition switch to OFF position. Remove LFC relay (engine cooling fan relay on models with only
one relay). See COOLING FAN RELAY LOCATIONS table. Using a DVOM, measure voltage
between negative battery terminal and B+ circuit at LFC relay cavity. See Fig. 321-Fig. 329 . If voltage is
more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, check for B+ circuit fault. Check
appropriate B+ circuit fuse to relay. See WIRING DIAGRAMS. If fuse is okay, check for open in B+
circuit to LFC relay. Repair as necessary. If fuse is blown, check B+ and LOW FAN PWR circuits for
short to ground before replacing fuse. Repair as necessary. Recheck cooling fan operation.

43) Check For Open LOW FAN PWR Circuit

Using a DVOM, measure resistance of LOW FAN PWR circuit between LFC relay cavity and
appropriate cooling fan harness connector(s). If resistance is less than 5 ohms, go to step 75). If resistance
is 5 ohms or more, locate and repair open in affected circuit. Recheck cooling fan operation.

46) High Speed Fan Inoperative: Command High Speed Fan ON & Check For Voltage To Cooling
Fan

Ensure ignition switch is in ON position, scan tool is in OUTPUT TEST MODE and high speed cooling
fan commanded OFF. Disconnect appropriate cooling fan connector (both connectors on models with 2
cooling fans). Using scan tool, command high speed fan ON. Using a DVOM, measure voltage between
negative battery terminal and HIGH FAN PWR circuit at appropriate cooling fan harness connector. See
Fig. 322-Fig. 324 or Fig. 329 . If voltage is 10 volts or less, go to next step. If voltage is more than 10
volts, check GND circuit to cooling fan. If GND circuit is okay, replace cooling fan and recheck cooling
fan operation.

47) Check B+ Voltage To HFC Relay

Turn ignition switch to OFF position. Remove HFC relay. See COOLING FAN RELAY LOCATIONS
table. Using a DVOM, measure voltage between negative battery terminal and B+ circuit at HFC relay
cavity. See Fig. 322-Fig. 324 or Fig. 329 . If voltage is more than 10.5 volts, go to next step. If voltage is
10.5 volts or less, check B+ circuit for fault. Check appropriate B+ circuit fuse. If fuse is okay, check for
open in B+ circuit to HFC relay. Repair as necessary. If fuse is blown, check B+ and HIGH FAN PWR
circuits for short to ground before replacing fuse. Repair as necessary. Recheck cooling fan operation.

48) Check For Open HIGH FAN PWR Circuit

Ensure ignition switch is in OFF position. Using a DVOM, measure resistance of HIGH FAN PWR
circuit between HFC relay cavity and appropriate cooling fan harness connector. See Fig. 322-Fig. 324 or
Fig. 329 . If resistance is less than 5 ohms, go to step 75). If resistance is 5 ohms or more, repair open in
HIGH FAN PWR circuit. Recheck cooling fan operation.

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips
from step 43) to step 46). No test procedures have been omitted.

2003 Ford Pickup F150

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

50) Low &/Or High Speed Cooling Fan Inoperative: Check For B+ Voltage To HFC & LFC Relays
Ensure ignition switch is in ON position, scan tool is in OUTPUT TEST MODE and cooling fan
commanded OFF. Remove LFC and HFC relays. See COOLING FAN RELAY LOCATIONS table.
Using a DVOM, measure voltage between negative battery terminal and B+ circuit at both LFC relay and
HFC relay cavity. See Fig. 330. If both voltage measurements are more than 10.5 volts, go to next step. If
either voltage measurement is 10.5 volts or less, check for B+ circuit fault. Check appropriate B+ circuit
fuse. If fuse is okay, check for open in B+ circuit. Repair as necessary. If fuse is blown, check B+ and
LOW or HIGH FAN PWR circuits for short to ground before replacing fuse. Repair as necessary.
Recheck cooling fan operation.

51) Check For Open Fan PWR Circuit, Fan Ground & Internal Fan Circuits

Ensure ignition switch is in OFF position. Using a DVOM, measure resistance between negative battery
terminal and FAN PWR circuit at both the LFC and HFC relay cavity. See Fig. 330. If both resistance
measurements are less than 15 ohms, go to next step. If either resistance measurement is 15 ohms or
more, go to step 56).

52) Check FAN PWR Circuit For Short To Ground In Harness

Disconnect both cooling fan harness connectors. Using a DVOM, measure resistance between chassis
ground and FAN PWR circuit at cooling fan harness connector. If resistance is more than 10 k/ohms, go
to next step. If resistance is 10 k/ohms or less, locate and repair short to ground in FAN PWR circuit.
Recheck cooling fan operation.

53) Check HFC & LFC Relay Operation

Leave cooling fans disconnected. Reinstall HFC and LFC relays. Turn ignition switch to ON position.
Using scan tool, access OUTPUT TEST MODE. See

OUTPUT TEST MODE

under ADDITIONAL

SYSTEM FUNCTIONS. Perform appropriate relay test procedure:

z

HFC Relay

Using scan tool, command high speed fan ON. Wait 15 seconds. Using a DVOM, measure voltage
between negative battery terminal and FAN PWR circuit at cooling fan harness connector (either
connector). Voltage should be more than 10.5 volts.

z

LFC Relay

Using scan tool, command low speed fan ON. Using a DVOM, measure voltage between negative
battery terminal and FAN PWR circuit at cooling fan harness connector (either connector). Voltage

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips
from step 48) to step 50). No test procedures have been omitted.

NOTE:

On models with 2 cooling fans, if one cooling fan is inoperative and the
other cooling fan operates normally, go to step 70).

2003 Ford Pickup F150

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

should be more than 10 volts.

If both voltage measurements are as specified, replace cooling fan(s). If either voltage measurement is not
as specified, note which fan speed is inoperative and go to step 75).

56) Check For Open FAN PWR Circuit Between Cooling Fan, & HFC & LFC Relays

Turn ignition switch to OFF position. Disconnect cooling fan connector (either connector). Using a
DVOM, measure resistance of FAN PWR circuit between cooling fan harness connector and specified
HFC and LFC relay cavity. See Fig. 330. If both resistance measurements are less than 15 ohms, go to
next step. If either resistance measurement is 15 ohms or more, locate and repair open in FAN PWR
circuit. If open is only between LFC relay and cooling fan, check fan dropping resistor in LOW FAN
PWR circuit. See COOLING FAN RESISTOR LOCATIONS table. Recheck cooling fan operation.

COOLING FAN RESISTOR LOCATIONS

57) Check Cooling Fan Ground Circuit

Using a DVOM, measure resistance between negative battery terminal and ground circuit at cooling fan
harness connector. If resistance is less than 5 ohms, replace inoperative cooling fan(s). If resistance is 5
ohms or more, locate and repair open in ground circuit. Recheck cooling fan operation.

60) Low, Medium &/Or High Speed Cooling Fan Always Runs (No DTCs): Ensure Fan Is Not On
Because Of A/C High Pressure Switch Input To PCM
Turn ignition switch to OFF position. Connect scan tool to Data Link Connector (DLC). Start engine and
allow to idle. Using scan tool, access ACP PID from PID/DATA MONITOR & RECORD menu. If ACP
PID indicates CLOSED, PCM will operate cooling fan when A/C high pressure switch is "closed". Leave
engine running and go to next step. If ACP PID does not indicate CLOSED, ACP input is correct. Go to
step 151) to check secondary circuits to cooling fan (Sable and Taurus), or go to step 65) (all others).

61) Check A/C High Pressure Switch (Normally Open Contacts)

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips
from step 53) to step 56). No test procedures have been omitted.

Application

Location

Windstar

In Engine Compartment, Between Battery & Left Headlight

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips
from step 57) to step 60). No test procedures have been omitted.

NOTE:

Perform test step 60) when directed from ELECTRIC COOLING FAN
ALWAYS ON symptom under SYMPTOMS in TROUBLE SHOOTING - NO
CODES - CNG, FLEX-FUEL & GASOLINE article.

NOTE:

A/C high pressure switch may also be referred to as dual pressure switch.

2003 Ford Pickup F150

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