Ford 2003 Mustang Workshop Manual page 3743

PINPOINT TEST I: THE DEFROST SYSTEM WILL NOT SHUT OFF
AUTOMATICALLY
I1 CHECK CIRCUIT 727 (YE/BK)
Disconnect: Heated Rear Window Relay.
Key in ON position.
Depress the rear window defroster switch to OFF.
Measure the resistance between heated rear window
relay pin 85, circuit 727 (YE/BK) , harness side and
ground.
Is the resistance greater than 10,000 ohms?
I2 CHECK CIRCUIT 727 (YE/BK) FOR A SHORT TO
GROUND
Key in OFF position.
Measure the resistance between instrument cluster
module (ICM) C220a pin 10, circuit 727 (YE/BK) ,
harness side and ground.
Is the resistance greater than 10,000 ohms?
I3 CHECK CIRCUIT 186 (BN/LB) FOR A SHORT TO POWER
Disconnect: Heated Rear Window Grid Power Supply
Connector C402a.
Measure the voltage between heated rear window grid
C402a circuit 186 (BN/LB), harness side and ground.
Test Step
caused by a loose or
corroded connector.
CLEAR the DTCs.
REPEAT the self-test.
Result / Action to Take
Yes
GO to I3 .
No
GO to I2 .
Yes
GO to I4 .
No
REPAIR the circuit. TEST the
system for normal operation.
Yes
REPAIR the circuit. TEST the
system for normal operation.
No
INSTALL a new heated rear
window relay. TEST the
system for normal operation.