key FORD MUSTANG 2003 Workshop Manual

z
Is the resistance reading less than 10,000 ohms? C13 CHECK CIRCUIT 198 (DG/OG) FOR A SHORT TO
GROUND z
Connect: A/C Pressure Cut- off Switch C1078.
z Measure the resistance between PCM C175- 41, circuit
198 (DG/OG), harness side and ground.
z Is the resistance less than 10,000 ohms? Yes
GO to
C15 .
No
INSTALL a new A/C fuse (15A).
TEST the system for normal
operation. If the fuse opens,
install a new PCM. REFER to
the Powertrain
Control/Emissions Diagnosis
(PC/ED) manual. C14 CHECK THE A/C PRESSURE CUT-
OFF SWITCH z
Disconnect: A/C Pressure Cut-off Switch C1078.
z Measure the resistance between the Rotunda EEC- V
Breakout Box pin 41, circuit 198 (DG/OG), and ground.
z Is the resistance less than 10,000 ohms? Yes
REPAIR circuit 198 (DG/OG)
for a short to ground. TEST the
system for normal operation.
No
INSTALL a new A/C pressure
cut-
off switch. REFER to
Section 412 - 03 .
C15 CHECK THE FUNCTION SELECTOR SWITCH
z
Key in OFF position.
z Connect: Function Selector Switch C294c.
z Disconnect: A/C Cycling Switch C130.
z Key in ON position.
z Turn the function selector switch to the A/C position.
z Measure the voltage between C130- 4, circuit 348 (VT),
harness side and ground. Yes
GO to
C17 .
No
GO to C16 . Klj . 19 ba
412003 Mustang Workshop Manual
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z
Is the voltage reading greater than 10 volts? C16 MEASURE THE RESISTANCE OF CIRCUIT 348 (VT)
z
Key in OFF position.
z Disconnect: Function Selector Switch C294c.
z Measure the resistance between the A/C function
selector switch C294c- 1, circuit 348 (VT), harness side
and A/C cycling switch C130- 4, circuit 348 (VT), harness
side.
z Is the resistance reading less than 5 ohms? Yes
INSTALL a new function
selector switch. REFER to
Section 412
- 04 . TEST the
system for normal operation.
No
REPAIR circuit 348 (VT) for an
open. TEST the system for
normal operation. C17 MEASURE THE VOLTAGE TO THE A/C PRESSURE
CUT- OFF SWITCH z
Key in OFF position.
z Connect: A/C Cycling Switch C130.
z Disconnect: A/C Pressure Cut-off Switch C1078.
z Turn the function selector switch to the A/C position.
z NOTE: The A/C pressure cut- off switch C1078 for the
3.8L engine is shown, C1078 for the 4.6L engines is
similar. The pin locations and the circuits are identical.
z Measure the voltage at the A/C high pressure cut- off
switch C1078- 2 circuit 420 (DB/YE), harness side and
ground. Yes
GO to
C19 .
No
GO to C18 . Klj . 20 ba
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z
Is the voltage reading greater than 10 volts? C18 CHECK THE A/C CYCLING SWITCH
z
Key in OFF position.
z Disconnect: A/C Cycling Switch C130.
z NOTE: The A/C pressure cut- off switch C1078 for the
3.8L engine is shown, C1078 for the 4.6L engines is
similar. The pin locations and the circuits are identical.
z Measure the resistance between A/C cycling switch
C130- 2, circuit 420 (DB/YE), harness side and the A/C
high pressure cut- off switch C1078-2, circuit 420
(DB/YE), harness side.
z Is the resistance less than 5 ohms? Yes
INSTALL a new A/C cycling
switch. REFER to
Section 412 -
03 . TEST the system for
normal operation.
No
REPAIR circuit 420 (DB/YE) for
an open. TEST the system for
normal operation. C19 CHECK THE A/C PRESSURE CUT-
OFF SWITCH z
Key in OFF position.
z NOTE: The A/C pressure cut- off switch C1078 for the
3.8L engine is shown, C1078 for the 4.6L engines is
similar. The pin locations and the circuits are identical.
z Measure the resistance between Rotunda Breakout Box
pin 41 and A/C high pressure cut- off switch C1078-3,
circuit 198 (DG/OG), harness side.
z Is the resistance less than 5 ohms? Yes
INSTALL a new A/C pressure
cut-
off switch. REFER to
Section 412 - 03 . TEST the
system for normal operation.
No
REPAIR circuit 198 (DG/OG)
for an open. TEST the system
for normal operation. C20 CHECK THE GROUND CIRCUIT AT THE CONSTANT
CONTROL RELAY MODULE z
Key in OFF position. Yes Klj . 21 ba
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z
Disconnect: CCRM C1262.
z Measure the resistance of CCRM C1262- 18, circuit 1205
(BK), harness side and ground.
z Is the resistance reading less than 5 ohms? GO to
C21 .
No
REPAIR circuit 1205 (BK) for
an open. TEST the system for
normal operation. C21 CHECK CIRCUIT 20 (WH/LB) AT THE CONSTANT
CONTROL RELAY MODULE z
Key in ON position.
z Measure the voltage at the CCRM C1262- 13, circuit 20
(WH/LB), harness side and ground.
z Is the voltage reading greater than 10 volts? Yes
GO to
C22 .
No
REPAIR circuit 20 (WH/LB) for
an open. TEST the system for
normal operation. C22 CHECK THE POWER TO THE A/C CLUTCH
z
Key in OFF position.
z Connect: CCRM 1262.
z Disconnect: A/C Clutch C100.
z Turn the function selector to the A/C position.
z Measure the voltage at the A/C clutch C100, circuit 347
(BK/YE), harness side and ground. Yes
GO to
C24 .
No
GO to C23 . Klj . 22 ba
412003 Mustang Workshop Manual
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z
Is the voltage greater than 10 volts? C23 CHECK CIRCUIT 331 (PK/YE) FOR AN OPEN.
z
Key in OFF position.
z Disconnect: CCRM C1262.
z Key in ON position.
z Enter the following diagnostic mode on the diagnostic
tool:
z In the Active Command Mode command the PCM
outputs ON.
z Measure the resistance between the CCRM C1262- 22,
circuit 331 (PK/YE), harness side and ground.
z Is the resistance reading less than 5 ohms? Yes
GO to
C24 .
No
REPAIR circuit 331 (PK/YE) for
an open. TEST the system for
normal operation. C24 CHECK CIRCUIT 347 (BK/YE)
z
Key in OFF position.
z Measure the resistance between CCRM C1262- 23,
circuit 347 (BK/YE), harness side and A/C clutch C100-
1, harness side.
z Is the resistance less than 5 ohms? Yes
GO to
C25 .
No
REPAIR circuit 347 (BK/YE) for
an open. TEST the system for
normal operation. C25 CHECK CIRCUIT 347 (BK/YE) FOR A SHORT TO
GROUND. z
Measure the resistance between A/C clutch C100- 2,
circuit 1205 (BK), harness side and the CCRM C1262-
16, circuit 1205 (BK) harness side. Yes
INSTALL a new constant
control relay module. TEST the
system for normal operation. Klj . 23 ba
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PINPOINT TEST D: THE A/C IS ALWAYS ON z
Is the resistance less than 5 ohms? No
REPAIR circuit 1205 (BK) for
an open. TEST the system for
normal operation.
Test Step Result / Action to Take
D1 CHECK PCM PID WACF
z
Turn the function selector switch to the OFF position.
z Key in ON position.
z Enter the following diagnostic mode on the diagnostic
tool: PCM PID WACF.
z Does the PCM PID WACF read YES? Yes
REPAIR circuit 331 (PK/YE) for
a short to ground. TEST the
system for normal operation.
No
GO to
D2 .
D2 CHECK PID ACCS WITH A/C OFF
z
Enter the following diagnostic mode on the diagnostic
tool: PCM PID ACCS.
z Does the PCM PID ACCS read ON? Yes
GO to
D3 .
No
GO to D5 .
D3 CHECK FOR A FALSE INPUT SIGNAL TO THE PCM
z
Key in OFF position.
z Disconnect: PCM C175.
z Key in ON position.
z Turn the function selector switch to the OFF position.
z Measure the voltage between PCM C175- 41, circuit 198
(DG/OG) harness side and ground.
z Is the voltage greater than 10 volts? Yes
GO to
D4 .
No
INSTALL a new powertrain
control module. REFER to
Section 303 - 14 . TEST the
system for normal operation. D4 CHECK CIRCUIT 198 (DG/OG) FOR A SHORT TO B+
z
Key in OFF position.
z Disconnect: Function Selector Switch C294c.
z Connect: PCM C175.
z Key in ON position.
z Measure the voltage at the function selector switch Yes
REPAIR circuit 348 (PK) for a
short to B+. TEST the system
for normal operation. Klj . 24 ba
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PINPOINT TEST E: INSUFFICIENT A/C COOLING C294c-
3, circuit 348 (PK), harness side and ground.
z Is there voltage present? No
INSTALL a new function
selector switch. REFER to
Section 412
- 04 . TEST the
system for normal operation. D5 CHECK FOR A SHORTED CLUTCH INPUT
z
Key in OFF position.
z Disconnect: A/C Clutch C100.
z Key in ON position.
z Measure for voltage at the A/C clutch C100, circuit 347
(BK/YE), harness side and ground.
z Is there voltage present? Yes
INSTALL a new constant
control relay module. TEST the
system for normal operation.
No
CHECK the clutch air gap.
REFER to
Air Conditioning (A/C) Clutch Air Gap
Adjustment .
Test Step Result / Action to Take
E1 CHECK THE CENTER A/C REGISTER DISCHARGE
TEMPERATURE z
Carry out the refrigerant system tests. Refer to
Refrigerant System Tests in this section.
z Use the recorded data from the refrigerant system tests
to plot a vertical line for ambient temperature and a
horizontal line for center A/C register discharge
temperature.
z Is the intersection of the two lines within the upper
and lower limits? Yes
The tests indicate that the
system is functioning normally.
No
GO to
E2 . Klj . 25 ba
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PINPOINT TEST F: NO OPERATION IN ALL TEMPERATURE
SETTINGS
PINPOINT TEST G: THE BLOWER MOTOR DOES NOT
OPERATE/DOES NOT OPERATE CORRECTLY INSTALL a new A/C
compressor due to low
performance. REFER to
Section 412
- 03 . TEST the
system for normal operation. Test Step Result / Action to Take
F1 CHECK THE TEMPERATURE CONTROL
z
Start the engine and run at idle. Allow the engine to reach
normal operating temperature.
z Place the function selector switch in the NORMAL A/C
position.
z Adjust the temperature control to full warm position, and
physically feel the discharge air temperature at the at the
center panel vents.
z Rotate the temperature control to full cold position, and
physically feel the discharge air temperature at the center
panel vents.
z Does the discharge air temperature vary? Yes
The temperature blend
door is functioning
correctly. RETURN to the
symptom chart.
No
GO to
F2 .
F2 CHECK FOR A BROKEN A/C TEMPERATURE CONTROL
CABLE z
Remove the climate control assembly to gain access to the
control cable head.
z Move the temperature control from full warm to full cold.
z Inspect the cable control head as you move the temperature
control.
z Does the alignment mark on the control head move? Yes
INSTALL a new
evaporator housing.
REFER to
Section 412 -
02 .
No
INSTALL a new
temperature control cable
assembly. REFER to
Section 412 - 04 .
Test Step Result / Action to Take
G1 CHECK FOR VOLTAGE AT C238
z
Disconnect: Blower Motor Jumper C238.
z Key in ON position.
z Turn the blower motor selector to LOW.
z Turn the function selector to FLOOR.
z Check for voltage between C238- 6, circuit 249 (DB/LG) and
C238- 3, circuit 261 (OG/BK). Yes
GO to
G2 .
No
GO to G4 . Klj . 30 ba
412003 Mustang Workshop Manual
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z
Is the voltage greater than 10 volts? G2 CHECK THE BLOWER MOTOR FOR VOLTAGE
z
Key in OFF position.
z Connect: Blower Motor Jumper C238.
z Disconnect: Blower Motor C2066.
z Key in ON position.
z Measure voltage between terminals of blower motor.
z Check for voltage between circuit 249 (DB/LG) and circuit
261 (OG/BK).
z Is the voltage greater than 10 volts? Yes
INSTALL a new blower
motor. REFER to
Section 412 - 02 . TEST the system
for normal operation.
No
GO to G3 .
G3 CHECK THE A/C BLOWER MOTOR JUMPER WIRE
z
Key in OFF position.
z Disconnect: Blower Motor Jumper C238.
z Key in ON position.
z Check circuit 261 (OG/BK) for an open between C2066 and
C238- 4.
z Is the resistance greater than 5 ohms? Yes
REPAIR circuit 261
(OG/BK). TEST the system
for normal operation.
No
INSTALL a new blower
motor. REFER to
Section 412 - 02 . TEST the system
for normal operation. G4 CHECK CIRCUIT 249 (DB/LG)
z
Check for voltage between C238- 6, circuit 249 (DB/LG),
harness side and ground. Yes
GO to
G5 .
No
GO to G8 . Klj . 31 ba
412003 Mustang Workshop Manual
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z
Is the voltage greater than 10 volts? G5 CHECK CIRCUIT 249 (DB/LG) FOR OPEN
z
Check the resistance on circuit 249 (DB/LG) between C238-
3 and C2066.
z Is resistance less than 10,000 ohms? Yes
REPAIR circuit 249
(DB/LG) for an open. TEST
the system for normal
operation.
No
GO to
G6 .
G6 CHECK THE BLOWER MOTOR GROUND
z
Key in OFF position.
z Measure the resistance between the jumper C238- 3, circuit
261 (OG/BK), and ground.
z Is the resistance less than 5 ohms? Yes
GO to
G7 .
No
GO to G10 .
G7 CHECK CIRCUIT 261 (OG/BK) FOR AN OPEN CIRCUIT
z
Measure the resistance between the A/C blower motor
jumper C238- 3, circuit 261 (OG/BK) and the blower motor
switch C294a- 1. Yes
REPAIR the blower motor
jumper. TEST the system
for normal operation.
No
INSTALL a new blower
motor. REFER to
Section 412 - 02 . TEST the system
for normal operation. Klj . 32 ba
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