Ford 2003 Mustang Workshop Manual page 520

Key in ON position.
Does the brake warning indicator stay on?
B2 CHECK PARKING BRAKE SWITCH
Key in OFF position.
Disconnect: Parking Brake Switch.
Key in ON position.
Does the brake warning light stay on?
B3 CHECK THE GEM
Key in OFF position.
Disconnect: GEM C201e.
Measure resistance to ground at C201e-13.
Is the resistance greater than 10,000 ohms?
B4 CHECK CIRCUITS 977 (VT/WH), 22 (LB/BK) AND 128
(VT/YE)
Remove the fused jumper from C124.
Measure the resistance to ground at C124-2.
Is the resistance greater than 10,000 ohms?
B5 CHECK CIRCUIT 128 (VT/YE)
Remove the fused jumper from C124.
Measure the resistance to ground at C201e-13.
cylinder reservoir. TEST the
system for normal operation.
Yes
GO to B3 .
No
INSTALL a new parking brake
switch. TEST the system for
normal operation.
Yes
REPAIR the GEM. TEST the
system for normal operation.
No
For vehicles without Daytime
Running Lights (DRL), GO to
B4 . For vehicles with DRL, GO
to B5 .
Yes
REPAIR the ground short in
circuit 128 (VT/YE). TEST the
system for normal operation.
No
REPAIR the ground short in
circuit 977 (VT/WH) or circuit 22
(LB/BK). TEST the system for
normal operation.
Yes
GO to B6 .