Section 13-00: Instrument Cluster and Panel Lighting
1994 Mustang Workshop Manual
DIAGNOSIS AND TESTING

Pinpoint Tests

  

PINPOINT TEST A: CONTROL ILLUMINATION INOPERATIVE

 

A1 CHECK FUSE 13 FOR VOLTAGE

Yes
TURN headlamp switch off. GO to A4.

No
GO to A2.

 

A2 CHECK SUPPLY VOLTAGE TO FUSE 13

Yes
TURN headlamp switch off. GO to A4.

No
GO to A3.

 

A3 CHECK CONTINUITY OF CIRCUIT 19 LB/R

  • Disconnect headlamp switch connector.
  • Check resistance of Circuit 19 LB/R between headlamp switch connector and instrument panel fuse 13.
  • Is there continuity?
Yes
REFER to Section 17-01 for headlamp switch diagnostics.

No
SERVICE open in Circuit 19 LB/R. RESTORE system. RETEST system.

 

A4 CHECK CIRCUIT 19 LB/R FOR SHORT TO GROUND

  • Measure resistance between load side of instrument panel fuse 13 and ground.
  • Is resistance less than 5 ohms?
Yes
SERVICE short to ground in Circuit 19 LB/R.

No
Short is internal to one of the components. RECONNECT one component at a time and check resistance to ground at load side of instrument panel fuse 13. REPLACE component which is internally shorted to ground.

  

PINPOINT TEST B: INSTRUMENT CLUSTER ILLUMINATION INOPERATIVE

 

B1 CHECK SWITCH OPERATION

  • Pull headlamp switch to PARK position.
  • Rotate headlamp switch knob and shaft fully counterclockwise without turning on dome lamps.
  • Are all instrument cluster illumination bulbs off?
Yes
TURN headlamp switch off. GO to B6.

No
TURN headlamp switch off. GO to B2.

 

B2 CHECK LH TURN SIGNAL INDICATOR

  • Turn ignition switch to RUN position.
  • Turn on LH turn signal.
  • Does LH turn indicator flash?
Yes
GO to B4.

No
GO to B3.

 

B3 CHECK CONTINUITY OF CIRCUIT 57 BK PIN 1

  • Turn ignition switch to OFF position
  • Check continuity between Pin 1 of instrument cluster connector J2 and ground.
  • Is there continuity?
Yes
REPLACE printed circuit. RESTORE system. RETEST system.

No
SERVICE open in Circuit 57 BK. RESTORE system. RETEST system.

 

B4 CHECK CONTINUITY OF CIRCUIT 57 BK PIN 12

  • Check continuity between Pin 12 of instrument cluster connector J2 and ground.
  • Is there continuity?
Yes
GO to B5.

No
SERVICE open in Circuit 57 BK. RESTORE system. RETEST system.

 

B5 CHECK CONTINUITY OF ILLUMINATION BULBS

  • Remove illumination bulbs from instrument cluster .
  • Check continuity of bulbs.
  • Do all bulbs have continuity?
Yes
REPLACE printed circuit. RESTORE system. RETEST system.

No
REPLACE burned out bulbs. RESTORE system. RETEST system.

 

B6 CHECK CIRCUIT 19 LB/R FOR SUPPLY VOLTAGE

  • Pull headlamp switch to PARK position.
  • Measure voltage at Pin 6 of instrument cluster connector J2.
  • Is battery voltage present?
Yes
GO to B5.

No
SERVICE open in Circuit 19 LB/R. RESTORE system. RETEST system.

  

PINPOINT TEST C: CLIMATE CONTROL ILLUMINATION INOPERATIVE

 

C1 CHECK CIRCUIT 19 LB/R FOR SUPPLY VOLTAGE

  • Remove A/C heater control . Refer to Section 12-03A.
  • Disconnect control illumination bulb connector.
  • Pull headlamp switch to PARK position.
  • Rotate headlamp switch knob and shaft fully counterclockwise without turning on dome lamps.
  • Measure voltage between Circuit 19 LB/R and ground.
  • Is battery voltage present?
Yes
GO to C2.

No
SERVICE open in Circuit 19 LB/R. RESTORE system. RETEST system.

 

C2 CHECK RESISTANCE OF CIRCUIT 57 BK

  • Measure resistance between Circuit 57 BK and ground.
  • Is resistance less than 5 ohms?
Yes
REPLACE illumination bulb. RESTORE system. RETEST system.

No
SERVICE open in Circuit 57 BK. RESTORE system. RETEST system.

  

PINPOINT TEST D: AUDIO SYSTEM ILLUMINATION INOPERATIVE

 

D1 CHECK CIRCUIT 19 LB/R FOR SUPPLY VOLTAGE

  • Remove radio chassis or digital audio compact disc player . Refer to Section 15-01.
  • Disconnect connectors.
  • Pull headlamp switch to PARK position.
  • Rotate switch knob fully counterclockwise without turning on dome lamp.
  • Measure voltage between Circuit 19 LB/R and ground.
  • Is battery voltage present?
Yes
GO to D2.

No
SERVICE open in Circuit 19 LB/R. RESTORE system. RETEST system.

 

D2 CHECK RESISTANCE OF CIRCUIT 57 BK

  • Measure resistance between Circuit 57 BK and ground.
  • Is resistance less than 5 ohms?
Yes
REMOVE radio chassis or digital audio compact disc player for service.

No
SERVICE open in Circuit 57 BK. RESTORE system. RETEST system.

  

PINPOINT TEST E: SINGLE ILLUMINATION SOURCE INOPERATIVE

 

E1 CHECK CIRCUIT 19 LB/R FOR SUPPLY VOLTAGE

  • Remove suspect switch. Refer to appropriate Section.
  • Disconnect connector(s).
  • Pull headlamp switch to PARK position.
  • Rotate headlamp switch knob and shaft fully counterclockwise without turning on dome lamps.
  • Measure voltage between Circuit 19 LB/R and ground.
  • Is battery voltage present?
Yes
GO to E2.

No
SERVICE open in Circuit 19 LB/R. RESTORE system. RETEST system.

 

E2 CHECK RESISTANCE OF CIRCUIT 57 BK

  • Measure resistance between Circuit 57 BK and ground.
  • Is resistance less than 5 ohms?
Yes
GO to E3.

No
SERVICE open in Circuit 57 BK. RESTORE system. RETEST system.

 

E3 DETERMINE SERVICEABILITY OF BULB

  • Check continuity of bulb.
  • Is illumination bulb serviceable?
Yes
REPLACE illumination bulb. RESTORE system. RETEST system.

No
REPLACE component. RESTORE system. RETEST system.