Ford F150 Pickup. Instruction - part 1590

or corroded terminals. Repair as necessary. Turn ignition switch to ON position. Using a DVOM, 
measure voltage between chassis ground and ACCS circuit at PCM harness connector terminal No. 41. 
See Fig. 372-Fig. 375 . If voltage is less than one volt, replace PCM (ZX2), or go to next step (Mustang). 
If voltage is one volt or more, repair short to B+ or VPWR in ACCS circuit. 

128) Check ACCS Circuit Voltage To PCM With CCRM Connected 
 
Turn ignition switch to OFF position. Leave A/C cycling switch and PCM disconnected. Reconnect 
CCRM. Turn ignition switch to ON position. Using a DVOM, measure voltage between chassis ground 
and ACCS circuit at PCM harness connector terminal No. 41. If voltage is less than one volt, replace 
PCM. If voltage is one volt or more, replace CCRM. 

130) Ensure A/C Turns Off When A/C Demand Switch Is Turned Off 
Turn A/C demand switch off. If A/C turns off, go to next step. If A/C does not turn off, go to step 140). 

131) Check If A/C Cuts Off During Wide Open Throttle 
 
Start engine and allow to idle. Turn A/C on. Briefly snap throttle wide open and then allow it to return to 
idle. Listen for A/C clutch disengagement during Wide Open Throttle (WOT), then re-engagement after a 
few seconds of returning to idle. A click noise will be heard when A/C clutch re-engages. Repeat test 
several times. If A/C clutch clicking noise cannot be heard, disconnect A/C clutch. Connect a test light 
between A/C CLUTCH PWR and A/C CLUTCH GND circuits at A/C clutch coil harness connector. 
Again, briefly snap throttle to wide open position and return to idle. Test light should be off during WOT 
and illuminate after a few seconds of returning to idle. Repeat test if necessary. If A/C clutch or test light 
operates as specified, turn ignition switch to OFF position and reconnect A/C clutch (if necessary). WAC 
circuit is functioning properly at this time. Go to TEST Z, step 

1)

and check for intermittent faults. If A/C 

clutch or test light does not operate as specified, go to next step. 

132) No Wide Open Throttle A/C Cut-Off (No DTCs): Check CCRM 
 
Turn ignition switch to OFF position. Reconnect A/C clutch (if necessary). Turn ignition switch to ON 
position. Using scan tool, access OUTPUT TEST MODE. See OUTPUT TEST MODE under 
ADDITIONAL SYSTEM FUNCTIONS. Turn A/C demand switch on. While observing A/C clutch 
engagement, command ALL OUTPUTS OFF and then ON several times. If A/C clutch engagement 
cycles, WOT A/C relay is operating properly at this time. If symptom is intermittent, go to TEST Z, step 
1), otherwise see appropriate article in AIR CONDITIONING & HEATING to diagnose A/C system 
concern. If A/C clutch does not cycle, ensure A/C clutch was engaged before commanding ALL 
OUTPUTS OFF. If not, repeat test with A/C clutch engaged. If A/C clutch was engaged prior to 
commanding ALL OUTPUTS OFF, replace CCRM. 

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips 
from step 128) to step 130). No test procedures have been omitted.

NOTE:

Diagnostic procedures beginning with step 130) are performed when 
directed here from CLIMATE CONTROL (LACK OF A/C COOLING, A/C 
ALWAYS ON OR A/C INOPERATIVE) under SYMPTOMS in TROUBLE 
SHOOTING - NO CODES - CNG, FLEX-FUEL & GASOLINE article.

 

2003 Ford Pickup F150 

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

  

135) ACPSW PID Indicates CLOSED With A/C High Pressure (ACP) Switch Disconnected: Check 
ACPSW Circuit For Short To GND In Harness 
Turn ignition switch to OFF position. Disconnect ACP switch connector. Disconnect scan tool from Data 
Link Connector (DLC). Disconnect PCM connector. Inspect connector for loose, damaged or corroded 
terminals. Repair as necessary. Using a DVOM, measure resistance between chassis ground and ACPSW 
circuit at PCM harness connector terminal No. 86. See Fig. 373-Fig. 375 . If resistance is more than 10 
k/ohms, replace PCM. If resistance is 10 k/ohms or less, repair short to GND in ACPSW circuit. 

140) A/C Always On: Check For Voltage At A/C Clutch With A/C Off 
Turn ignition switch to OFF position. Turn A/C and defroster off. Disconnect A/C clutch. Connect a 
DVOM between A/C CLUTCH PWR and A/C CLUTCH GND circuits at A/C clutch harness connector. 
Start engine and allow to idle. If voltage is 2 volts or more, a fault is indicated in A/C electrical system. 
Go to next step. If voltage is less than 2 volts, electrical portion of A/C system is okay. If A/C related 
symptom still exists, see appropriate article in AIR CONDITIONING & HEATING to diagnose A/C 
system concern. 

141) Check ACCS Input To PCM With A/C Off 
 
Turn ignition switch to OFF position. Connect scan tool to Data Link Connector (DLC). Ensure A/C and 
defroster are off. Start engine and allow to idle. Using scan tool, access ACCS PID from PID/DATA 
MONITOR & RECORD menu. If ACCS PID value indicates ON, go to step 125). If ACCS PID value 
indicates OFF, check A/C system and repair as necessary. See appropriate article in AIR 
CONDITIONING & HEATING. 

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips 
from step 132) to step 135). No test procedures have been omitted.

NOTE:

Step 135) is performed when directed here from step 81).

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips 
from step 135) to step 140). No test procedures have been omitted.

NOTE:

Diagnostic procedures beginning with step 140) are performed when 
directed here from step 130), or from CLIMATE CONTROL (LACK OF A/C 
COOLING, A/C ALWAYS ON OR A/C INOPERATIVE) 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 141) to step 145). No test procedures have been omitted.

NOTE:

Diagnostic procedures beginning with step 145) are performed when 
directed here from step 98).

NOTE:

A fault in A/C high pressure switch MEDIUM PRESSURE circuit can cause 

 

2003 Ford Pickup F150 

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

  

Fig. 378: Testing Medium Pressure Circuits At High Pressure Switch 
Courtesy of FORD MOTOR CO. 

145) Check A/C High Pressure Switch Medium Pressure Circuits 
Turn ignition switch to OFF position. Disconnect A/C High Pressure (ACP) switch. Ensure A/C is off. 
Connect jumper wire between ACPSW and ground circuits at ACP switch harness connector. See Fig. 
378. Start engine and allow to idle for 15 seconds. If high speed fan does not come on, an ACP switch 
MEDIUM PRESSURE circuit concern may exist. Go to next step. If high speed fan comes on, ACP 
switch MEDIUM PRESSURE circuits are okay. Turn ignition switch to OFF position. Remove jumper 
wire and reconnect ACP switch connector. See appropriate article in AIR CONDITIONING & 
HEATING to diagnose A/C system concern. 

146) Check For Open Ground Circuit To ACP Switch 
 
With engine still running, move jumper wire from ACP switch connector ground terminal to negative 
battery terminal. Wait 15 seconds. If high speed fan now comes on, turn ignition switch to OFF position. 
Remove jumper wire and repair open ground circuit to ACP switch. If high speed fan does not come on, 
remove jumper wire and go to next step. 

high speed cooling fan not to operate when A/C pressure is high. Hot 
ambient conditions may cause refrigerant pressure to increase until A/C 
high pressure switch HIGH PRESSURE contacts open, turning off A/C until 
pressure drops to an acceptable range.

 

2003 Ford Pickup F150 

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

  

147) Check For Open ACPSW Circuit Between ACP Switch & PCM 
 
Disconnect PCM connector. Using a DVOM, measure resistance of ACPSW circuit between PCM 
harness connector and ACP switch connector. See PCM CONNECTOR IDENTIFICATION and Fig. 
378. If resistance is less than 5 ohms, replace PCM. If resistance is 5 ohms or more, repair open in 
ACPSW circuit.  

TEST Z: INTERMITTENT 

Diagnostic Aids 

Perform this test when instructed during QUICK TEST or if directed by other test procedures. This system test 
is intended to diagnose and isolate intermittent concerns for the following:  

z

All Engine Control Sub-Systems  

z

Coil Pack Ignition Systems Using Distributorless Ignition System Tester (DIST)  

The intermittent test table is used to determine which test to perform for a suspect circuit. See 
INTERMITTENT TEST table. Corresponding PIDs for each circuit are listed. Some circuits do not have an 
associated PID and can be measured with a Digital Volt-Ohmmeter (DVOM). If vehicle has coil pack ignition 
system and engine is a no-start, perform ignition test. Go to step 50). 

INTERMITTENT TEST 

NOTE:

TEST Z is designed for PCM intermittents. When directed here to diagnose Rear 
Electronics Module (REM), these diagnostic procedures can be used to help 
with REM diagnosis.

NOTE:

For additional Parameter Identification (PID) information, see appropriate PIN 
VOLTAGE/PID VALUE CHARTS article.

PID

Associated Circuit

Test Type

4X4L

4X4L

Input

ACCS

A/CCS

Input

ACP & ACP V

A/CP

Input

 

AFC

Input

AIR

AIR

Output

AIR B

AIRB

Output

AIR D

AIRD

Output

AIR M

AIRM

Input

BARO

BARO

Input

BPP/BOO

BPP

Input

 

BPS

Input

CAMDCR

CAMDCR

Output

 

2003 Ford Pickup F150 

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