Pinpoint Test D: The Steering Wheel Switch Illumination Is Inoperative

NOTE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.

D1 CHECK THE OTHER DIMMABLE LIGHTING SWITCHES
- Ignition OFF.
- Place the headlamp switch in the PARKING LAMPS ON position.
- Rotate the instrument panel dimmer switch to the full illumination position and observe other dimmable switches.
- Are all the dimmable switches inoperative?
- Yes : GO to PINPOINT TEST B .
- No : GO to D2.
D2 CHECK FOR VOLTAGE TO THE CLOCKSPRING
- Place the headlamp switch in the OFF position.
- Depower the Supplemental Restraint System (SRS). Refer to SUPPLEMENTAL RESTRAINT SYSTEM article.
- Disconnect: Clockspring C218a.
- Connect: Negative Battery Cable.
- Place the headlamp switch in the PARKING LAMPS ON position.
- Increase the backlighting brightness to the highest setting.
- Measure the voltage between the clockspring C218a-16, circuit VLN37 (BU/WH), harness side and ground.
  
  Fig 1: Measuring Voltage Between Clockspring C218A-16, Circuit VLN37 (BU/WH) And Ground
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
- Yes : GO to D3.
- No : REPAIR circuit VLN37 (BU/WH) for an open. REPOWER the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM article. TEST the system for normal operation.
D3 CHECK THE CLOCKSPRING GROUND FOR AN OPEN
- Measure the voltage between the clockspring C218a-16, circuit VLN37 (BU/WH), harness side and the clockspring C218a-5, circuit GD114 (BK/BU), harness side.
  
  Fig 2: Measuring Voltage Between Clockspring C218A-16, Circuit VLN37 (BU/WH) And Clockspring C218A-5, Circuit GD114 (BK/BU), Harness Side
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
- Yes : GO to D4.
- No : REPAIR circuit GD114 (BK/BU) for an open. REPOWER the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM article. TEST the system for normal operation.
D4 CHECK THE CLOCKSPRING FOR AN OPEN
- Remove the driver air bag module. Refer to SUPPLEMENTAL RESTRAINT SYSTEM article.
- Disconnect: Upper Clockspring C218b.
- Measure the resistance between the clockspring C218a pin 5, component side and the upper clockspring C218b pin 4, component side.
  
  Fig 3: Measuring Resistance Between Clockspring C218A Pin 5, Component Side And Upper Clockspring C218B Pin 4, Component Side
  Courtesy of FORD MOTOR CO.
- Measure the resistance between the clockspring C218a pin 16, component side and the upper clockspring C218b pin 7, component side.
  
  Fig 4: Measuring Resistance Between Clockspring C218A Pin 16 And Upper Clockspring C218B Pin 7, Component Side
  Courtesy of FORD MOTOR CO.
- Are the resistances less than 5 ohms?
- Yes : INSTALL a new steering wheel. REFER to STEERING COLUMN article. TEST the system for normal operation.
- No : INSTALL a new clockspring. INSTALL the driver air bag module. REFER to SUPPLEMENTAL RESTRAINT SYSTEM article. TEST the system for normal operation.