Pinpoint Test Y: The Alternating Flashing Headlamps Are 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.

Y1 CHECK CIRCUITS 1337 (VT/YE) (LH HEADLAMP) AND 1335 (YE/WH) (RH HEADLAMP) FOR AN OPEN
- Key in OFF position.
- Disconnect: Wig-Wag Module C1365.
- Place the headlamp switch in the HEADLAMPS ON position.
- Place the multifunction switch in the HIGH BEAM position.
- Measure the voltage between the wig-wag module C1365-D (LH headlamp), circuit 1337 (VT/YE), harness side and ground; and between the wig-wag module C1365-B (RH headlamp), circuit 1335 (YE/WH), harness side and ground.
  
  Fig 1: Checking Circuits 1337 (VT/YE) (LH Headlamp) And 1335 (YE/WH) (RH Headlamp) For An Open
  Courtesy of FORD MOTOR CO.
- Are the voltages greater than 10 volts?
Yes : GO to Y2.

No : REPAIR the circuit in question. TEST the system for normal operation.
Y2 CHECK CIRCUIT 7 (LG/YE) FOR AN OPEN
- Place the headlamp switch in the OFF position.
- Key in ON position.
- Activate the switch for the wig-wag module.
- Measure the voltage between the wig-wag module C1365-A, circuit 7 (LG/YE), harness side and ground.
  
  Fig 2: Measuring Voltage Between Wig-Wag Module C1365-A, Circuit 7 (LG/YE), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
Yes : GO to Y3.

No : REPAIR the circuit. TEST the system for normal operation.
Y3 CHECK CIRCUIT 57 (BK) FOR AN OPEN
- Key in OFF position.
- Measure the resistance between the wig-wag module C1365-C, circuit 57 (BK), harness side and ground.
  
  Fig 3: Measuring Resistance Between Wig-Wag Module C1365-C, Circuit 57 (BK), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes : INSTALL a new wig-wag module. TEST the system for normal operation.

No : REPAIR the circuit. TEST the system for normal operation.