Pinpoint Test C: The Instrument Cluster Illumination Is Inoperative

C1 CHECK CIRCUIT 235 (RD/BK) FOR VOLTAGE
- Disconnect: Instrument Cluster C220b.
- Place the headlamp switch in the PARK position.
- Rotate the dimmer switch to the maximum brightness position.
- Measure the voltage between the instrument cluster C220b-12, circuit 235 (RD/BK), harness side and ground.
  
  Fig 1: Measuring Voltage Between Instrument Cluster C220b-12, Circuit 235 (RD/BK), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
1. Yes : GO to C2.
2. No : REPAIR the circuit. TEST the system for normal operation.
C2 CHECK CIRCUIT 1205 (BK) FOR AN OPEN
- Place the headlamp switch in the OFF position.
- Measure the resistance between the instrument cluster C220b-11, circuit 1205 (BK), harness side and ground.
  
  Fig 2: Measuring Resistance Between Instrument Cluster C220b-11, Circuit 1205 (BK), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
1. Yes : GO to C3.
2. No : REPAIR the circuit. TEST the system for normal operation.
C3 CHECK FOR CORRECT INSTRUMENT CLUSTER OPERATION
- Disconnect all the instrument cluster connectors.
- Check for:
- corrosion
- pushed-out pins
- Connect all the instrument cluster connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
1. Yes : INSTALL a new instrument cluster. REFER to INSTRUMENT CLUSTER . TEST the system for normal operation.
2. No : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.