Pinpoint Test D: The Steering Wheel Switch(Es) Illumination Is Inoperative

WARNING: This page is about a different car, the 2014 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.

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 ON.
- Place the headlamp switch in the PARKING LAMPS ON position.
- Press and hold the instrument panel dimmer switch up to the full illumination position and observe other dimmable switches.
Are all the dimmable steering wheel switches inoperative?
- Yes : GO to PINPOINT TEST A .
- No : If all the steering wheel switches illumination is inoperative, GO to D2 .
  If only one steering wheel switch illumination is inoperative, GO to D5.
D2 CHECK THE HORN OPERATION
- Press the driver air bag module against the steering wheel.
Does the horn sound?
- Yes : GO to D3 .
- No : REFER to HORN to diagnose the horn is inoperative.
D3 CHECK FOR VOLTAGE TO THE STEERING WHEEL SWITCHES
- Place the headlamp switch in the OFF position.
- Remove the driver air bag module. Refer to DRIVER AIRBAG .
- Disconnect: Clockspring C218B .
- Ignition ON.
- Place the headlamp switch in the PARKING LAMPS ON position.
- Press and hold the instrument panel dimmer switch up to the full illumination position.
- Measure the voltage between the clockspring C218B-9 , component side and the clockspring C218B-10 , component side.
  
  Fig 1: Measuring Voltage Between Clockspring C218B-9 And Clockspring C218B-10
  Courtesy of FORD MOTOR CO.
Is the voltage greater than 10 volts?
- Yes : INSTALL a new steering wheel. REFER to STEERING WHEEL . TEST the system for normal operation.
- No : GO to D4 .
D4 CHECK FOR VOLTAGE TO THE CLOCKSPRING
- Disconnect: Clockspring C218A .
- Measure the voltage between the clockspring C218A-9 , circuit VLN04 (VT/GY), harness side and the clockspring C218A-8 , circuit GD133 (BK), harness side.
  
  Fig 2: Measuring Voltage Between Clockspring C218A-9, Circuit VLN04 (VT/GY) And Clockspring C218A-8, Circuit GD115 (BK/GY)
  Courtesy of FORD MOTOR CO.
Is the voltage greater than 10 volts?
- Yes : INSTALL a new clockspring. REFER to CLOCKSPRING . TEST the system for normal operation.
- No : REPAIR circuit VLN04 (VT/GY) for an open. TEST the system for normal operation.

D5 CHECK THE SUSPECT STEERING WHEEL SWITCH FOR VOLTAGE

Disconnect: Suspect Steering Wheel Switch.
Press and hold the instrument panel dimmer switch up to the full illumination position.

Measure the voltage between the inoperative illumination source, harness side as follows:

Component	Connector-Pin	Connector-Pin
Steering wheel switch - LH	C2998-2	C2998-4
Steering wheel switch - RH	C2999-1	C2999-3

Fig 3: Measuring Voltage Between Inoperative Illumination Source, Harness Side

Courtesy of FORD MOTOR CO.

Is the voltage greater than 10 volts?

Yes : INSTALL a new component for the one in question. TEST the system for normal operation.
No : INSTALL a new steering wheel. REFER to STEERING WHEEL . TEST the system for normal operation.