Pinpoint Test E: The Auxiliary Audio Control Is Inoperative - Steering Wheel Controls

WARNING: This page is about a different car, the 2006 Mercury Grand Marquis and 2006 Ford Crown Victoria. However, it is still accessible from the selected car via links, so may be relevant.

E1 CHECK THE STEERING WHEEL CONTROLS (SWITCHES PRESSED)

Key in OFF position.
Disconnect: Audio Unit C290a.

Measure the resistance between the audio unit C290a-18, circuit 595 (LB/RD), harness side and ground while pressing the steering wheel controls as follows:

STEERING WHEEL CONTROLS RESISTANCE RANGE

Switch	Resistance range
VOL down	30-132 ohms
VOL up	132-312 ohms
NEXT	312-642 ohms

Fig 1: Measuring Resistance Between Audio Unit C290A-18, Circuit 595 (LB/RD) And Ground

Courtesy of FORD MOTOR CO.

Are the resistances within specification?

Yes : REMOVE the audio unit. REFER to AUDIO UNIT . SEND it to an authorized audio system repair facility. TEST the system for normal operation after the repair.

No : GO to E2.

E2 CHECK THE STEERING WHEEL CONTROLS (NO SWITCHES PRESSED)
- Measure the resistance between the audio unit 3290a-18, circuit 595 (LB/RD), harness side and ground with no switches pressed.
  
  Fig 2: Measuring Resistance Between Audio Unit C290A-18, Circuit 595 (LB/RD) And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance between 2,894 and 10,800 ohms?
Yes : INSTALL new steering wheel controls. REFER to STEERING WHEEL CONTROLS . TEST the system for normal operation.

No : GO to E3.
E3 CHECK CIRCUIT 595 (LB/RD) FOR AN OPEN OR A SHORT TO GROUND
- Disconnect: Clockspring C218a.
- Measure the resistance between the audio unit C290a-18, circuit 595 (LB/RD), harness side and the clockspring C218a-5, circuit 595 (LB/RD), harness side; and between the audio unit C290a-18, circuit 595 (LB/RD), harness side and ground.
  
  Fig 3: Checking Circuit 595 (LB/RD) For An Open Or A Short To Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms between the audio unit and clockspring, and greater than 10,000 ohms between the audio unit and ground?
Yes : GO to E4.

No : REPAIR the circuit(s). TEST the system for normal operation.
E4 CHECK CIRCUIT 57 (BK) FOR AN OPEN
- Measure the resistance between the clockspring C218a-15, circuit 57 (BK), harness side and ground.
  
  Fig 4: Measure Resistance Of Circuit 57 (BK) For Open
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes : GO to E5.

No : REPAIR the circuit. TEST the system for normal operation.
E5 CHECK THE SIGNAL CIRCUIT IN THE STEERING WHEEL HARNESS
- Depower the driver air bag module. Refer to SUPPLEMENTAL RESTRAINT SYSTEM .
- Disconnect: Steering Wheel Controls C2208.
- Disconnect: Clockspring C218b.
- Measure the resistance between the steering wheel controls C2208-5, circuit 595 (LB/RD), harness side and the clockspring C218b-9, circuit 595 (LB/RD), harness side.
  
  Fig 5: Measuring Resistance Between Steering Wheel Controls C2208-5 And Clockspring C218B-9
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes : GO to E6.

No : REPAIR the circuit. REPOWER the driver air bag module. REFER to SUPPLEMENTAL RESTRAINT SYSTEM . TEST the system for normal operation.
E6 CHECK CIRCUIT 57 (BK) IN THE STEERING WHEEL HARNESS FOR AN OPEN
- Measure the resistance between the steering wheel controls C2208-3, circuit 57 (BK), harness side and the clockspring C218b-7, circuit 57 (BK), harness side.
  
  Fig 6: Measuring Resistance Between Steering Wheel Controls C2208-3 And Clockspring C218B-7
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes : GO to E7.

No : REPAIR the circuit. REPOWER the driver air bag module. REFER to SUPPLEMENTAL RESTRAINT SYSTEM . TEST the system for normal operation.
E7 CHECK THE CLOCKSPRING FOR AN OPEN
- Measure the resistance between the clockspring C218a-5, component side and the clockspring C218b-9, component side; and between the clockspring C218a-15, component side and the clockspring C218b-7, component side.
  
  Fig 7: Checking The Clockspring For An Open
  Courtesy of FORD MOTOR CO.
- Are the resistances less than 5 ohms?
Yes : INSTALL new steering wheel controls. REFER to STEERING WHEEL CONTROLS . REPOWER the driver air bag module. REFER to SUPPLEMENTAL RESTRAINT SYSTEM . TEST the system for normal operation.

No : INSTALL a new clockspring. REFER to SUPPLEMENTAL RESTRAINT SYSTEM . REPOWER the driver air bag module. REFER to SUPPLEMENTAL RESTRAINT SYSTEM . TEST the system for normal operation.