Ford 2003 Mustang Workshop Manual page 3501

Is the voltage greater than 10 volts?
B10 CHECK CIRCUIT 1034 (BK/WH) FOR OPEN
Disconnect: GEM C201c.
Measure the resistance between GEM C201c Pin 3, Circuit
1034 (BK/WH), harness side and dome/map lamp C929
(coupe) Pin 3 or map lamp C978 (convertible) Pin 4, Circuit
1034 (BK/WH), harness side.
Is the resistance less than 5 ohms?
B11 CHECK CIRCUIT 1205 (BK) FOR OPEN
Measure the resistance between dome/map lamp C929
(coupe) Pin 2 or map lamp C978 (convertible) Pin 1, Circuit
1205 (BK), harness side and ground.
Is the resistance less than 5 ohms?
B12 CHECK CIRCUIT 1034 (BK/WH) FOR SHORT TO BATTERY
Measure the voltage between GEM C201c Pin 3, Circuit 1034
(BK/WH), harness side and ground.
Yes
INSTALL a new GEM. For
additional information,
REFER to Section 419-
10 . REPEAT the self-test.
CLEAR the DTCs.
No
REPAIR the circuit.
REPEAT the self-test.
CLEAR the DTCs.
Yes
INSTALL a new
dome/map lamp
assembly. For additional
information, REFER to
Lamp Assembly—
Map/Dome .
No
REPAIR the circuit.
REPEAT the self-test.
CLEAR the DTCs.
Yes
REPAIR the circuit.
REPEAT the self-test.
CLEAR the DTCs.
No
INSTALL a new GEM. For
additional information,
REFER to Section 419-
10 . REPEAT the self-test.
CLEAR the DTCs.