Section 17-02: Lighting, Interior
1994 Mustang Workshop Manual
DIAGNOSIS AND TESTING

Pinpoint Tests—Courtesy Lamps

  

PINPOINT TEST AA: COURTESY LAMPS INOPERATIVE

 

AA1 CHECK FUSE 8 (10A) FOR VOLTAGE

Yes
GO to AA3.

No
GO to AA2.

 

AA2 CHECK CIRCUIT 54 (LG/Y) FOR SHORT

Yes
SERVICE, Circuit 54 (LG/Y) for short to ground. RESTORE vehicle. RETEST system. REPLACE fuse 8 (10A).

No
GO to AA3.

 

AA3 CHECK SUPPLY VOLTAGE AT COURTESY LAMP SWITCHES

  • Remove courtesy lamp switch at each door . (If sedan, remove courtesy lamp switch at rear door also.) Leave courtesy lamp switch connected to harness.
  • Using a test lamp connected to a known good ground, check Circuit 54 (LG/Y) for voltage at each courtesy lamp switch .
  • Is voltage present at all courtesy lamp switches ?
Yes
GO to AA4.

No
SERVICE Circuit 54 (LG/Y) at suspect courtesy lamp switch for open circuit. RESTORE vehicle. RETEST system.

 

AA4 CHECK COURTESY LAMP SWITCHES

  • Disconnect courtesy lamp switches .
  • Using an ohmmeter, check for continuity at all switch terminals of each courtesy lamp switch .
  • Is there continuity at all switch terminals?
Yes
GO to AA5.

No
REPLACE courtesy lamp switch . RESTORE vehicle. RETEST system.

 

AA5 CHECK HEADLAMP SWITCH SUPPLY

  • Remove headlamp switch . Leave headlamp switch connected.
  • Using voltmeter, test terminal D1 Circuit 54 (LG/Y) for voltage.
  • Is voltage present?
Yes
GO to AA6.

No
SERVICE Circuit 54 (LG/Y) for open circuit. RESTORE vehicle. RETEST system.

 

AA6 CHECK HEADLAMP SWITCH OUTPUT

  • Remove voltmeter from terminal D1 and connect it to terminal D2 Circuit 706 (GY).
  • Turn headlamp switch counterclockwise to the stop.
  • Is voltage present?
Yes
SERVICE Circuit 53 (BK/BL) for open. RESTORE vehicle. RETEST system.

No
REPLACE headlamp switch . RESTORE vehicle. RETEST system.

  

PINPOINT TEST AB: ENGINE COMPARTMENT LAMPS INOPERATIVE

 

AB1 CHECK ENGINE COMPARTMENT LAMP SUPPLY

  • Remove engine compartment lamp as outlined.
  • Using a voltmeter check Circuit 54 (LG/Y) for voltage.
  • Is voltage present?
Yes
GO to AB2.

No
SERVICE Circuit 54 (LG/Y) for open circuit. RESTORE vehicle. RETEST system.

 

AB2 CHECK ENGINE COMPARTMENT LAMP GROUND

  • Using an ohmmeter connected to a known good ground, check continuity of Circuit 57 (BK) at engine compartment lamp .
  • Is there continuity?
Yes
GO to AB3.

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

 

AB3 CHECK ENGINE COMPARTMENT LAMP MINIATURE BULB

  • Remove engine compartment lamp miniature bulb .
  • Using an ohmmeter, check continuity of miniature bulb .
  • Does miniature bulb test OK?
Yes
REPLACE engine compartment lamp . RESTORE vehicle. RETEST system.

No
REPLACE engine compartment lamp miniature bulb . RESTORE vehicle. RETEST system.

  

PINPOINT TEST AC: LUGGAGE COMPARTMENT LAMPS INOPERATIVE

 

AC1 CHECK LUGGAGE COMPARTMENT LAMP SUPPLY

  • Disconnect luggage compartment lamp .
  • Using a test lamp connected to a known good ground, check Circuit 54 (LG/Y) for voltage.
  • Did test lamp illuminate?
Yes
GO to AC2.

No
SERVICE Circuit 54 (LG/Y) for open circuit. RESTORE vehicle. RETEST system.

 

AC2 CHECK CIRCUIT 55 (BK/PK)

  • Using a jumper wire, jumper both terminals in luggage compartment lamp switch connector.
  • Did luggage compartment lamp illuminate?
Yes
REPLACE luggage compartment lamp switch. RESTORE vehicle. RETEST system.

No
GO to AC3.

 

AC3 CHECK CIRCUIT 55 (BK/PK) FOR OPEN

  • Leave jumper wire connected.
  • Using a test lamp check Circuit 55 (BK) at luggage compartment lamp for voltage.
  • Did test lamp illuminate?
Yes
GO to AC4.

No
SERVICE Circuit 55 (BK/PK) for open circuit. RESTORE vehicle. RETEST system.

 

AC4 CHECK CIRCUIT 57 (BK)

  • Using an ohmmeter connected to a known good ground, check Circuit 57 (BK) for continuity.
  • Is there continuity?
Yes
GO to AC5.

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

 

AC5 CHECK LUGGAGE COMPARTMENT LAMP BULB

  • Remove bulb from lamp assembly.
  • Using an ohmmeter check continuity of bulb.
  • Does bulb test OK?
Yes
REPLACE luggage compartment lamp assembly. RESTORE vehicle. RETEST system.

No
REPLACE luggage compartment lamp bulb. RESTORE vehicle. RETEST system.

  

PINPOINT TEST AD: GLOVE COMPARTMENT LAMP INOPERATIVE

 

AD1 CHECK GLOVE COMPARTMENT LAMP SUPPLY

  • Disconnect glove compartment lamp connector.
  • Using a voltmeter, check Circuit 54 (LG/Y) for voltage.
  • Is voltage present?
Yes
GO to AD2.

No
SERVICE Circuit 54 (LG/Y) for open circuit. RESTORE vehicle. RETEST system.

 

AD2 CHECK GLOVE COMPARTMENT LAMP BULB

  • Remove glove compartment lamp bulb.
  • Using an ohmmeter, check continuity of glove compartment lamp bulb.
  • Is there continuity?
Yes
REPLACE glove compartment lamp switch and wire . RESTORE vehicle. RETEST system.

No
REPLACE glove compartment lamp bulb. RESTORE vehicle. RETEST system.

  

PINPOINT TEST AE: VANITY MIRROR LAMPS INOPERATIVE

 

AE1 CHECK VANITY MIRROR LAMPS SUPPLY

  • Remove vanity mirror lamp assembly as outlined.
  • Disconnect vanity mirror .
  • Using a voltmeter, check Circuit 54 (LG/Y) for voltage.
  • Is voltage present?
Yes
GO to AE2.

No
SERVICE Circuit 54 (LG/Y) for open circuit. RESTORE vehicle. RETEST system.

 

AE2 CHECK VANITY MIRROR LAMPS GROUND

  • Remove vanity mirror lamp bulb.
  • Using an ohmmeter connected to a known good ground, check ground side of bulb socket for continuity.
  • Is there continuity?
Yes
GO to AE3.

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

 

AE3 CHECK VANITY MIRROR LAMP BULB

  • Using an ohmmeter, check continuity of bulb.
  • Is there continuity?
Yes
REPLACE vanity mirror lamp assembly. RESTORE vehicle. RETEST system.

No
REPLACE vanity mirror lamp bulb. RESTORE vehicle. RETEST system.

  

PINPOINT TEST AF: INDIVIDUAL COURTESY LAMP INOPERATIVE

 

AF1 CHECK SUPPLY TO COURTESY LAMP

  • Remove suspect courtesy lamp assembly.
  • Using a voltmeter, check Circuit 54 (LG/Y) for voltage.
  • Is voltage present?
Yes
GO to AF2.

No
SERVICE Circuit 54 (LG/Y) for open circuit. RESTORE vehicle. RETEST system.

 

AF2 CHECK GROUND CIRCUIT 57 (BK)

  • Using an ohmmeter connected to a known good ground, connect second lead to Circuit 57 (BK), check continuity.
  • Is there continuity?
Yes
GO to AF3.

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

 

AF3 CHECK COURTESY LAMP BULB

  • Remove courtesy lamp miniature bulb .
  • Using an ohmmeter, check miniature bulb for continuity.
  • Is there continuity?
Yes
REPLACE courtesy lamp assembly. RESTORE vehicle. RETEST system.

No
REPLACE courtesy lamp miniature bulb . RESTORE vehicle. RETEST system.