Section 17-01: Lighting, Exterior
1994 Mustang Workshop Manual
DIAGNOSIS AND TESTING

Pinpoint Tests—Turn Signal Lamps/Hazard Flasher Lamps

  

PINPOINT TEST CA: TURN SIGNALS LAMPS INOPERATIVE

 

CA1 CHECK SUPPLY TO ELECTRONIC INDICATOR FLASHER

Yes
GO to CA4.

No
GO to CA2.

 

CA2 CHECK SUPPLY AT FUSE 1 (15A)

Yes
SERVICE Circuit 298 (P/O) for open circuit. RESTORE vehicle. RETEST system.

No
GO to CA3.

 

CA3 CHECK SUPPLY TO FUSE 1 (15A)

  • Using a test lamp, check input side of fuse 1 (15A).
  • Did test lamp illuminate?
Yes
REPLACE damaged fuse 1 (15A). RESTORE vehicle. RETEST system.

No
SERVICE Circuit 687 (GY/Y) for open circuit. RESTORE vehicle. RETEST system.

 

CA4 CHECK BATTERY SUPPLY TO ELECTRONIC INDICATOR FLASHER

  • Using a test lamp, check Circuit 385 (W/R) for voltage.
  • Did test lamp illuminate?
Yes
GO to CA7.

No
GO to CA5.

 

CA5 CHECK SUPPLY AT FUSE 9 (15A)

  • Using test lamp, check output side of fuse 9 (15A).
  • Did test lamp illuminate?
Yes
SERVICE Circuit 383 (R/W) for open circuit. RESTORE vehicle. RETEST system.

No
GO to CA6.

 

CA6 CHECK SUPPLY TO FUSE 9 (15A)

  • Using test lamp, check input side of fuse (15A).
  • Did test lamp illuminate?
Yes
REPLACE damaged fuse 9 (R/W). RESTORE vehicle. RETEST system.

No
SERVICE Circuit 38 (BK/O) for open circuit. RESTORE vehicle. RETEST system.

 

CA7 CHECK ELECTRONIC INDICATOR FLASHER GROUND

  • Using an ohmmeter connected to a known good ground, connect second lead to Circuit 57 (BK) at electronic indicator flasher . Measure resistance.
  • Is resistance 5 ohms or less?
Yes
GO to CA8.

No
SERVICE Circuit 57 (BK) for open circuit. RESTORE vehicle. RETEST system.

 

CA8 CHECK CIRCUIT 44 (LB)

  • Disconnect electronic indicator flasher .
  • Connect one lead of an ohmmeter to Circuit 44 (LB) at flasher connector, connect second lead to Circuit 44 (LB) at Pin H of turn signal and windshield wiper switch .
  • Check continuity.
  • Is there continuity?
Yes
RECONNECT indicator flasher . GO toCA9.

No
SERVICE Circuit (LB) for open circuit. RESTORE vehicle. RETEST system.

 

CA9 CHECK ELECTRONIC INDICATOR FLASHER OUTPUT

  • Using a test lamp connected to a known good ground, check Circuit 44 (LB) for voltage.
  • Did test lamp illuminate?
Yes
GO to CA10.

No
REPLACE damaged electronic indicator flasher . RESTORE vehicle. RETEST system.

 

CA10 CHECK TURN SIGNAL AND WINDSHIELD WIPER SWITCH OUTPUT

  • Actuate turn signal and windshield wiper switch to the left turn position.
  • Using a test lamp connected to a known good ground, connect other end to Circuit 3 (LG/W) Pin J at turn signal and windshield wiper switch .
  • Did test lamp illuminate?
Yes
REPLACE electronic indicator flasher . RESTORE vehicle. RETEST system.

No
REPLACE damaged turn signal and windshield wiper switch . RESTORE vehicle. RETEST system.

  

PINPOINT TEST CB: INDIVIDUAL TURN SIGNAL LAMP INOPERATIVE

 

CB1 CHECK TURN SIGNAL AND WINDSHIELD WIPER SWITCH OUTPUT

  • Gain access to turn signal and windshield wiper switch connector.
  • Turn ignition switch to RUN position.
  • Actuate turn signal and windshield wiper switch in suspect lamp position.
  • Connect one end of a test lamp to a known good ground, and the other end to suspect lamp circuit per chart:

    Pin Circuit Function
    J 3 (LG/W) Left Front Turn Signal
    C 9 (LG/O) Left Rear Turn Signal
    F 2 (W/LB) Right Front Turn Signal
    D 5 (O/LB) Right Rear Turn Signal

  • Did test lamp illuminate?
Yes
LEAVE turn signal and windshield wiper switch actuated. GO toCB2.

No
REPLACE damaged turn signal and windshield wiper switch . RESTORE vehicle. RETEST system.

 

CB2 CHECK SUSPECT LAMP SUPPLY

  • Gain access to suspect lamp connector as outlined. Disconnect suspect lamp.
  • Using a test lamp connected to a known good ground, connect other end to the suspect circuit per chart:

    Circuit Function
    3 (LG/W) Left Front Turn Signal
    9 (LG/O) Left Rear Turn Signal
    2 (W/LB) Right Front Turn Signal
    5 (O/LB) Right Rear Turn Signal

  • Did test lamp illuminate?
Yes
GO to CB3.

No
GO to CB5.

 

CB3 CHECK SUSPECT LAMP GROUND

  • Using an ohmmeter connected to a known good ground, connect second lead to Circuit 57 (BK) at suspect lamp connector.
  • Measure resistance.
  • Is resistance 5 ohms or less?
Yes
GO to CB4.

No
SERVICE Circuit 57 (BK) for open circuit. RESTORE vehicle. RETEST system.

 

CB4 CHECK SUSPECT MINIATURE BULB

  • Using an ohmmeter, check continuity of suspect miniature bulb .
  • Is there continuity?
Yes
SERVICE damaged lamp socket. RESTORE vehicle. RETEST system.

No
REPLACE damaged miniature bulb .

 

CB5 CHECK SUSPECT LAMP CIRCUIT

  • Turn ignition switch to OFF position.
  • Disconnect the turn signal and windshield wiper switch .
  • Using an ohmmeter connected to a known good ground, connect second lead to suspect circuit per chart:
  • Measure resistance.

    Pin Circuit Function
    J 3 (LG/W) Left Front Turn Signal
    C 9 (LG/O) Left Rear Turn Signal
    F 2 (W/LB) Right Front Turn Signal
    D 5 (O/LB) Right Rear Turn Signal

  • Is resistance 5 ohms or less?
Yes
SERVICE suspect circuit for short to ground. RESTORE vehicle. RETEST system.

No
SERVICE suspect circuit for open circuit. RESTORE vehicle. RETEST system.

  

PINPOINT TEST CC: HAZARD FLASHER LAMPS INOPERATIVE

 

CC1 CHECK SUPPLY TO ELECTRONIC INDICATOR FLASHER

  • Gain access to electronic indicator flasher .
  • Using a test lamp connected to a known good ground, check Circuit 383 (R/W) for voltage.
  • Did test lamp illuminate?
Yes
GO to CC4.

No
GO to CC2.

 

CC2 CHECK SUPPLY CIRCUIT TO ELECTRONIC INDICATOR FLASHER

  • Using a test lamp connected to a known good ground, check Circuit 383 (R/W) at output side of fuse 9 (15A).
  • Did test lamp illuminate?
Yes
SERVICE Circuit 383 (R/W) for open circuit. RESTORE vehicle. RETEST system.

No
GO to CC3.

 

CC3 CHECK CIRCUIT 383 (R/W) FOR SHORT

  • Using an ohmmeter connected to ground, connect second lead to output side of fuse 9 (15A) cavity. Measure resistance.
  • Is resistance 5 ohms or less?
Yes
SERVICE Circuit 383 (R/W) for short to ground. RESTORE vehicle. RETEST system.

No
REPLACE damaged fuse 9 (15A). RESTORE vehicle. RETEST system.

 

CC4 CHECK ELECTRONIC INDICATOR FLASHER GROUND

  • Using an ohmmeter connected to a known good ground, connect second lead to Circuit 57 (BK) at electronic indicator flasher . Measure resistance.
  • Is resistance 5 ohms or less?
Yes
GO to CC5.

No
SERVICE Circuit 57 (BK) for open circuit. RESTORE vehicle. RETEST system.

 

CC5 CHECK CIRCUIT 383 (R/W)

  • Disconnect electronic indicator flasher .
  • Connect one lead of an ohmmeter to Circuit 383 (R/W) at electronic indicator flasher connector, and the second lead to Circuit 383 (R/W) at Pin I of turn signal and windshield wiper switch .
  • Check continuity.
  • Is there continuity?
Yes
RECONNECT electronic indicator flasher . GO toCC6.

No
SERVICE Circuit 383 (R/W) for open circuit. RESTORE vehicle. RETEST system.

 

CC6 CHECK ELECTRONIC INDICATOR FLASHER OUTPUT

  • Using a test lamp connected to a known good ground, check Circuit 383 (R/W) for voltage.
  • Did test lamp illuminate?
Yes
GO to CC7.

No
REPLACE damaged electronic indicator flasher . RESTORE vehicle. RETEST system.

 

CC7 CHECK TURN SIGNAL AND WINDSHIELD WIPER SWITCH OUTPUT

  • Actuate turn signal and windshield wiper switch to the hazard flasher position.
  • Using a test lamp connected to a known good ground, connect other end to Circuit 3 (LG/W) Pin J at turn signal and windshield wiper switch .
  • Did test lamp illuminate?
Yes
REPLACE electronic indicator flasher . RESTORE vehicle. RETEST system.

No
REPLACE damaged turn signal and windshield wiper switch . RESTORE vehicle. RETEST system.