Ford 2003 Mustang Workshop Manual page 3719

inoperative — rear,
convertible only
The defrost system is
inoperative
The defrost system will not
shut off automatically
Pinpoint Tests
PINPOINT TEST A: NO COMMUNICATION WITH THE GENERIC
ELECTRONIC MODULE (GEM)
CAUTION: Use the correct probe adapter(s) when making measurements. Failure to
use the correct probe adapter(s) may damage the connector.
A1 CHECK THE GENERIC ELECTRONIC MODULE (GEM)
POWER SUPPLY
Key in OFF position.
Disconnect: Generic Electronic Module (GEM) C201a.
Disconnect: GEM C201b.
Key in ON position.
Using the following table, measure the voltage between the
GEM, harness side and ground.
Connector Pin
C201a 4
C201a 1
C201b 2
C201b 3
Are the voltages greater than 10 volts?
A2 CHECK THE GEM GROUND CIRCUIT 397 (BK/WH) FOR
OPEN
Key in OFF position.
Measure the resistance between the GEM C201b pin 4,
circuit 397 (BK/WH), harness side and ground.
Window regulator
motor.
Driver window
regulator control
switch.
BJB fuse HTD BL
(30A).
CJB fuse 23 (15A).
Circuitry.
Instrument cluster
module (ICM).
Rear window
defrost switch.
Heated rear
window grid.
Circuit.
ICM.
Rear window
defrost switch.
Test Step
Circuit
400 (LB/BK)
1006 (DG/WH)
1001 (WH/YE)
193 (YE/LG)
Test G .
GO to Pinpoint
Test H .
GO to Pinpoint
Test I .
Result / Action to Take
Yes
GO to A2 .
No
REPAIR the circuit(s) in
question. TEST the system
for normal operation.
Yes
GO to A3 .
No