Ford 2003 Mustang Workshop Manual page 825

Disconnect: GEM C201b.
Key in ON position.
Using the following table. measure the voltage between the
GEM, harness side and ground.
Connector Pin
C201a 2
C201a 3
C201b 1
C201b 4
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 2,
circuit 397 (BK/WH), harness side and ground.
Is the resistance less than 5 ohms?
A3 CHECK CIRCUIT 397 (BK/WH) FOR SHORT TO POWER
Measure the voltage between GEM C201b pin 2, circuit 397
(BK/WH), harness side and ground.
Is any voltage present?
PINPOINT TEST B: THE IGNITION SWITCH IS INOPERATIVE
Test Step
B1 CHECK THE IGNITION SWITCH
Carry out the ignition switch component test.
REFER to Wiring Diagrams Cell 149,
Component Testing.
Is the ignition switch OK ?
Circuit
400 (LB/BK)
1006 (DG/WH)
1001 (WH/YE)
193 (YE/LG)
No
REPAIR the circuit(s) in
question. TEST the system
for normal operation.
Yes
GO to A3
No
REPAIR the circuit(s) in
question. TEST the system
for normal operation.
Yes
REPAIR the circuit. TEST
the system for normal
operation.
No
REFER to
Result / Action to Take
Yes
INSTALL a new BJB. TEST the system for
normal operation.
.
Section 418-00 .