Where is the turn signal flasher located on a 2005 mustang gt?

Does not use a flasher , controlled by SJB - smart junction box , module - computer etc...
Turn Signal and Hazard Lamps
All turn signal outputs are controlled by the SJB. The multifunction switch and the hazard switch are hard-wired to the SJB. When the multifunction switch is in the left or right turn position, or the hazard switch is engaged, the SJB processes this information and outputs the appropriate command to the turn signal and hazard lamps. All turn signal lamps provide a lamp outage indication.

Rather then trying to guess your way to a repair , Take it to a qualified repair shop. Could have DTC'S - diagnostic trouble code's stored that point in the correct diagnostic path .

Inspection and Verification

1. Verify the customer concern.

1. Visually inspect the following for obvious signs of mechanical or electrical damage.

• Multifunction switch
• Hazard switch

• Circuitry
• Bulbs
• Smart junction box (SJB)

1. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.

1. If the cause is not visually evident, connect the diagnostic tool to the data link connector (DLC) and select the vehicle to be tested from the diagnostic tool menu. If the diagnostic tool does not communicate with the vehicle:
   • check that the program card is correctly installed.
   • check the connections to the vehicle.
   • check the ignition switch position.

1. If the diagnostic tool still does not communicate with the vehicle, refer to the diagnostic tool operating manual.

1. Carry out the diagnostic tool data link test. If the diagnostic tool responds with:
   • CAN circuit fault; all electronic control units no response/not equipped, refer to Section 418-00 .
   • No response/not equipped for SJB, refer to Section 419-10 .
   • System passed, retrieve and record the continuous diagnostic trouble codes (DTCs), erase the continuous DTCs and carry out the self-test diagnostics for the SJB.

1. If the DTCs retrieved are related to the concern, go to the Smart Junction Box (SJB) Diagnostic Trouble Code (DTC) Index.

1. If no DTCs related to the concern are retrieved, GO to Symptom Chart .
2. Smart Junction Box (SJB) Diagnostic Trouble Code (DTC) Index DTC Description Action B1342 ECU is Faulted CLEAR the DTCs. RETRIEVE the DTCs. If DTC B1342 is retrieved again, INSTALL a new SJB. REFER to Section 419-10 . TEST the system for normal operation. B1499 Lamp Turn Signal Left Circuit Failure Go To Pinpoint Test K . B1501 Lamp Turn Signal Left Circuit Short to Battery Go To Pinpoint Test K . B1503 Lamp Turn Signal Right Circuit Failure Go To Pinpoint Test K . B1505 Lamp Turn Signal Right Circuit Short to Battery Go To Pinpoint Test K . B2048 Left Rear Turn Lamp Circuit Short to Ground REFER to Stoplamps in this section to continue diagnosis. B2049 Left Rear Turn Lamp Circuit Open REFER to Stoplamps in this section to continue diagnosis. B2050 Right Rear Turn Lamp Circuit Short to Ground REFER to Stoplamps in this section to continue diagnosis. B2051 Right Rear Turn Lamp Circuit Open REFER to Stoplamps in this section to continue diagnosis. B2071 Hazard Switch Signal Short to Ground If the hazard lamps are inoperative, Go To Pinpoint Test L .
   If the hazard lamps are always on, Go To Pinpoint Test M . B2281 Right Turn Switch Short to Ground Go To Pinpoint Test J . B2282 Left Turn Switch Short to Ground Go To Pinpoint Test J . B2529 Left Rear Turn Lamp Circuit Failure REFER to Stoplamps in this section to continue diagnosis. All other DTCs - REFER to Section 419-10 .