Pinpoint Test Aa: The Rear Deck Light Emitting Diode (Led) Flasher Is Inoperative

WARNING: This page is about a different car, the 2006 Mercury Grand Marquis and 2006 Ford Crown Victoria. However, it is still accessible from the selected car via links, so may be relevant.

AA1 CHECK THE REAR DECK LED FLASHER
- Key in OFF position.
- Disconnect: Rear Deck LED Flasher C4234.
- Connect a fused (10A) jumper wire between the rear deck LED flasher C4234 pin 2, component side and battery voltage; and connect a jumper wire between the rear deck LED flasher C4234 pin 3, component side and ground.
  
  Fig 1: Checking The Rear Deck LED Flasher
  Courtesy of FORD MOTOR CO.
- Do the rear deck LED flashing lights alternate flashing on and off?
Yes : REMOVE the jumper wires. GO to AA2.

No : INSTALL a new rear deck LED flasher. TEST the system for normal operation.
AA2 CHECK THE REAR DECK LED FLASHER GROUND CIRCUIT FOR AN OPEN
- Measure the resistance between the rear deck LED flasher C4234-3, circuit 57 (BK), harness side and ground.
  
  Fig 2: Checking The Rear Deck LED Flasher Ground Circuit For An Open
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes : REPAIR circuit 23 (TN/LG). TEST the system for normal operation.

No : REPAIR circuit 57 (BK). TEST the system for normal operation.