Pinpoint Test B: The Instrument Cluster Illumination Is Inoperative

Is the voltage greater than 10 volts? 

1. B1 CHECK VOLTAGE TO INSTRUMENT CLUSTER ILLUMINATION 
   • Disconnect: Instrument Cluster.
   • Place the headlamp switch in the ON position.
   • Rotate the instrument panel dimmer switch to the full illumination position.
   • Measure the voltage between the instrument cluster C220b pin 4, circuit 19 (LB/RD), harness side and ground.
     Fig 1: Checking Voltage To Instrument Cluster Illumination

     Courtesy of FORD MOTOR CO.
   1. Yes:  GO to B2.
   2. No:  REPAIR the circuit. TEST the system for normal operation.
2. B2 CHECK GROUND TO INSTRUMENT CLUSTER 
   • Place the headlamp switch in the OFF position.
   • Measure the resistance between the instrument cluster C220b pin 1, circuit 1205 (BK), harness side and ground.
     Fig 2: Checking Ground To Instrument Cluster

     Courtesy of FORD MOTOR CO.
   • Are the resistances less than 5 ohms? 
   1. Yes:  INSTALL a new instrument cluster. REFER to HORN . TEST the system for normal operation.
   2. No:  REPAIR the circuit. TEST the system for normal operation.