Ford F150 Pickup. Instruction - part 1587

commanding HIGH SPEED FAN ON). If cooling fan operates correctly (all speeds), cooling fan circuits 
are okay. Check engine cooling system for mechanical faults. See COOLING SYSTEM TROUBLE 
SHOOTING under ENGINE MECHANICAL in BASIC TROUBLE SHOOTING article in GENERAL 
INFORMATION. If cooling fan does not operate correctly, command cooling fan OFF, remain in 
OUTPUT TEST MODE and go to next step. 

41) Cooling Fan Concern: Check Cooling Fan For Operation At All Speeds 
 
On Mustang 3.8L, go directly to next step. On all others, if cooling fan did not operate at any speed 
during functional check, remain in OUTPUT TEST MODE and go to next step. If cooling fan operated at 
only one speed, remain in OUTPUT TEST MODE and go to step 50). 

42) Cooling Fan Will Not Operate At Any Speed: Command FAN ON & Check For Voltage At 
Cooling Fan 
 
Disconnect cooling fan connector. Command FAN ON (HIGH SPEED FAN ON for 2-speed 
applications). Using a DVOM, measure voltage between chassis ground and HIGH FAN PWR circuit 
(FAN PWR circuit on Mustang 3.8L) at cooling fan harness connector. If voltage is 10 volts or less, go to 
next step. If voltage is more than 10 volts, PWR is being supplied to cooling fan. Turn ignition switch to 
OFF position and go to step 45). 

43) Check For B+ To Fan Control Relays IN CCRM 
 
Turn ignition switch to OFF position. Disconnect CCRM connector. Using a DVOM, measure voltage 
between chassis ground and B+ circuits at CCRM harness connector terminals No. 3 and 4. See Fig. 372-
Fig. 375 . If both voltage measurements are more than 10 volts, go to next step. If either voltage 
measurement is 10 volts or less, fault exists in B+ circuit. Check condition of related fuses. If fuse is 
blown, check for short to ground in B+, or HIGH FAN PWR (FAN PWR on Mustang 3.8L) circuit. 
Repair as necessary. If fuse is okay, check for open B+ circuit. Repair as necessary, reconnect all 
components and recheck system operation. 

44) Check For Open FAN PWR Circuit Between CCRM & Cooling Fan 
 
Turn ignition switch to OFF position. Ensure CCRM and cooling fan are disconnected. Perform 
appropriate procedure: 

z

Mustang 3.8L 
 
Using a DVOM, measure resistance of FAN PWR circuit between cooling fan harness connector 
and CCRM harness connector. See Fig. 372 and Fig. 375 . If resistance is less than 7 ohms, go to 
step 70). If resistance is 7 ohms or more, locate and repair open in FAN PWR circuit between 
cooling fan and CCRM. After repair is complete, reconnect all components and recheck system 
operation. 

z

Mustang 4.6L & ZX2 
 
Using a DVOM, measure resistance of HIGH FAN PWR and LOW FAN PWR circuits between 

 

2003 Ford Pickup F150 

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

  

cooling fan harness connector and CCRM harness connector. See Fig. 373-Fig. 375 . If both 
resistance measurements are less than 7 ohms, replace CCRM. Ensure FAN PWR circuits are not 
shorted to ground. Reconnect all components and recheck system operation. If either resistance 
measurement is 7 ohms or more, locate and repair open circuit between cooling fan and CCRM. 
After repair is complete, reconnect all components and recheck system operation.  

45) Check For Open Cooling Fan Ground Circuit 
 
Disconnect scan tool from DLC. Using a DVOM, measure resistance of ground circuit between chassis 
ground and cooling fan harness connector. See Fig. 372-Fig. 375 . If resistance is 5 ohms or more, locate 
and repair open in ground circuit. Reconnect all components and recheck system operation. If resistance 
is less than 5 ohms, replace cooling fan. Reconnect all components and recheck system operation. 

50) Determine Which Fan Speed Is Operational 
 
If low speed fan is functioning properly, but high speed cooling fan is inoperative, go to step 65). If low 
speed fan is inoperative, go to next step. 

51) Low Speed Cooling Fan Inoperative: Command Low Speed Fan ON & Check For Voltage To 
Cooling Fan 
 
Turn ignition switch to OFF position. Disconnect cooling fan connector. Turn ignition switch to ON 
position. Using scan tool in OUTPUT TEST MODE, command LOW SPEED FAN ON. Using a DVOM, 
measure voltage between chassis ground and LOW FAN PWR circuit at cooling fan harness connector. 
On all models, if voltage is 10 volts or less, go to next step. If voltage is more than 10 volts, go to step 54)
(Mustang 4.6L), or replace cooling fan (ZX2). Reconnect all components and recheck system operation. 

52) Check For Open Low Fan Power Circuit Between CCRM & Cooling Fan 
 
Turn ignition switch to OFF position. Disconnect CCRM connector. Using a DVOM, measure resistance 
of LOW FAN PWR circuit between cooling fan harness connector and CCRM harness connector. See 
Fig. 372, Fig. 374 and Fig. 375 . If both resistance measurements are less than 5 ohms, go to step 70). If 
either resistance measurement is 5 ohms or more, locate and repair open in LOW FAN PWR circuit. 
Reconnect all components and recheck system operation. 

54) Check For Open Dropping Resistor On Fan Shroud Assembly 
 
Turn ignition switch to OFF position. Using a DVOM, measure resistance between LOW FAN PWR and 
HIGH FAN PWR circuits at cooling fan shroud assembly. See Fig. 373. If resistance is less than 6 ohms, 
replace cooling fan. If resistance is 6 ohms or more, carefully remove dropping resistor from mounts and 

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips 
from step 45) to step 50). No test procedures have been omitted.

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips 
from step 52) to step 54). No test procedures have been omitted.

 

2003 Ford Pickup F150 

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

  

check condition of resistor. Replace as necessary. If resistor is okay, replace cooling fan. 

65) High Speed Cooling Fan Inoperative: Command High Speed Fan ON & Check For Voltage To 
Cooling Fan 
 
Turn ignition switch to OFF position. Disconnect cooling fan connector. Turn ignition switch to ON 
position. Using scan tool in OUTPUT TEST MODE, command HIGH SPEED FAN ON. Using a 
DVOM, measure voltage between chassis ground and HIGH FAN PWR circuit at cooling fan harness 
connector. If voltage is 10.5 volts or less, go to next step. If voltage is more than 10.5 volts, replace 
cooling fan. Reconnect all components and recheck system operation. 

66) Check For Open High Fan Power Circuit 
 
Turn ignition switch to OFF position. Disconnect CCRM connector. Using a DVOM, measure resistance 
of HIGH FAN PWR circuit between cooling fan harness connector and CCRM harness connector. See 
Fig. 372, Fig. 374 and Fig. 375 . If resistance is less than 5 ohms, go to step 70). If resistance is 5 ohms 
or more, locate and repair open in HIGH FAN PWR circuit. Reconnect all components and recheck 
system operation. 

70) Attempt To Access PIDs With Scan Tool 
If scan tool being used is capable of accessing PIDs, go to next step. If scan tool is unable to access PIDs, 
go to step 73) (cooling fan inoperative on Mustang 3.8L, or low speed cooling fan inoperative on all 
others), or step 16) (high speed cooling fan inoperative). 

71) Check Operation Of Low Speed Or High Speed Cooling Fan Primary Circuits 
 
Reconnect all connectors. Turn ignition switch to ON position. Using scan tool, access OUTPUT TEST 
MODE. See 

OUTPUT TEST MODE

 under ADDITIONAL SYSTEM FUNCTIONS. Perform 

appropriate procedure: 

z

High Speed Fan Inoperative (Except Mustang 3.8L) 
 
Using scan tool, access HFC and HFCF PIDs from PID/DATA MONITOR & RECORD menu. 
With HFC PID OFF (high speed cooling fan commanded OFF by PCM), HFCF PID should 
indicate NO (no fault). Command HIGH SPEED FAN ON. HFC PID should now indicate ON and 
HFCF PID should still indicate NO. If HFCF PID value indicated YES (fault present) with HIGH 
SPEED FAN commanded ON or OFF, a primary circuit fault is detected. Go to step 15) and 

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips 
from step 54) to step 65). No test procedures have been omitted.

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips 
from step 66) to step 70). No test procedures have been omitted.

NOTE:

An inoperative high speed or low speed fan can be caused by a primary 
circuit fault, even though a DTC was not set.

 

2003 Ford Pickup F150 

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

  

perform diagnostics for DTC P1479. If HFCF PID indicated NO with high speed cooling fan 
commanded ON or OFF, primary circuits are okay. Replace CCRM. Ensure HIGH FAN PWR 
circuit is not shorted to ground. Recheck cooling fan operation. 

z

Low Speed Cooling Fan Inoperative (Cooling Fan Inoperative On Mustang 3.8L) 
 
Using scan tool, access LFC and LFCF PIDs from PID/DATA MONITOR & RECORD menu. 
With LFC PID OFF (low speed cooling fan commanded OFF by PCM), LFCF PID should indicate 
NO (no fault). Command LOW SPEED FAN ON. LFC PID should now indicate ON and LFCF 
PID should still indicate NO. If LFCF PID value indicated YES (fault present) with LOW SPEED 
FAN commanded ON or OFF, a primary circuit fault is detected. Go to step 20) and perform 
diagnostics for DTC P1474. If LFCF PID indicated NO with low speed cooling fan commanded 
ON or OFF, primary circuits are okay. Replace CCRM. Ensure LOW FAN PWR circuit (FAN 
PWR circuit on Mustang 3.8L) is not shorted to ground. Recheck cooling fan operation.  

73) Check FC/LFC Circuit For Short To Ground In Harness 
 
Turn ignition switch to OFF position. Disconnect scan tool from DLC. Disconnect PCM connector. 
Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Using a DVOM, 
measure resistance between chassis ground and FC/LFC circuit at CCRM harness connector. See Fig. 
372-Fig. 375 . If resistance is more than 10 k/ohms, replace CCRM. Ensure LOW FAN PWR (FAN PWR 
on Mustang 3.8L) circuit is not shorted to ground. If resistance is 10 k/ohms or less, repair short to 
ground in FC/LFC circuit. 

80) High &/Or Low Speed Cooling Fan Always Runs (No DTCs): Verify Fan Is Not On Due To A/C 
High Pressure Switch Input To PCM 
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 value indicates CLOSED, leave 
engine running and go to next step. If ACP PID value indicates OPEN, ACP switch input signal is okay. 
Go to step 82). 

81) Check A/C High Pressure Switch 

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips 
from step 71) to step 73). No test procedures have been omitted.

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips 
from step 73) to step 80). No test procedures have been omitted.

NOTE:

Diagnostic procedures beginning with step 80) are performed when 
directed here from ELECTRIC COOLING FAN ALWAYS ON under 
SYMPTOMS in TROUBLE SHOOTING - NO CODES - CNG, FLEX-FUEL & 
GASOLINE article.

NOTE:

PCM will turn on cooling fan when A/C high pressure switch (ACP PID) 
input signal is CLOSED.

 

2003 Ford Pickup F150 

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