Pinpoint Test E: The Power Lumbar Is Inoperative

WARNING: This page is about a different car, the 2013 Ford Mustang. However, it is still accessible from the selected car via links, so may be relevant.

E1 CHECK THE LUMBAR CONTROL SWITCH FOR VOLTAGE
- Ignition OFF.
- Depower the SRS. Refer to SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DEPOWERING AND REPOWERING .
- Disconnect: Driver Seat Side Air Bag C367.
- Disconnect: Lumbar Control Switch C361.
- WARNING: Make sure no one is in the vehicle and there is nothing blocking or placed in front of any airbag when the battery is connected. Failure to follow these instructions may result in serious personal injury in the event of an accidental deployment.
  
  Connect the battery ground cable. Refer to BATTERY, MOUNTING AND CABLES .
- Measure the voltage between lumbar control switch C361-4, circuit SBB32 (VT/RD), harness side and ground.
  
  Fig 1: Measuring Voltage Between Lumbar Control Switch C361-4, Circuit SBB32 (VT/RD) And Ground
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
- Yes : GO to E2.
- No : VERIFY Battery Junction Box (BJB) fuse 32 (30A) is OK. If OK, REPAIR the circuit. If not OK, REFER to the OEM WIRING DIAGRAMS to identify the possible causes of the circuit short. TEST the system for normal operation.
  DISCONNECT the battery ground cable. CONNECT driver seat side air bag module C367. REPOWER the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM .
E2 CHECK THE GROUND CIRCUIT FOR AN OPEN
- Measure the resistance between:
  - lumbar control switch C361-2, circuit GD133 (BK), harness side and ground.
  - lumbar control switch C361-8, circuit GD133 (BK), harness side and ground.
    
    Fig 2: Checking Ground Circuit For Open
    Courtesy of FORD MOTOR CO.
- Are the resistances less than 5 ohms?
- Yes : GO to E3.
- No : REPAIR the circuit. TEST the system for normal operation.
  DISCONNECT the battery ground cable. CONNECT driver seat side air bag module C367. REPOWER the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM .
E3 CHECK FOR VOLTAGE TO THE LUMBAR MOTOR
- Connect: Lumbar Control Switch C361.
- Disconnect: Power Lumbar Motor C366.
- Measure the voltage between power lumbar motor C366-1, circuit CPS64 (BN/VT), harness side and power lumbar motor C366-2, circuit CPS65 (WH/GN), harness side.
  
  Fig 3: Measuring Voltage Between Power Lumbar Motor C366-1, Circuit CPS64 (BN/VT) And Power Lumbar Motor C366-2
  Courtesy of FORD MOTOR CO.
- Operate the power lumbar control switch in both directions.
- Is the voltage greater than 10 volts in both directions?
- Yes : INSTALL a new power lumbar assembly. REFER to LUMBAR ASSEMBLY . TEST the system for normal operation.
  DISCONNECT the battery ground cable. CONNECT driver seat side air bag module C367. REPOWER the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM .
- No : GO to E4.
E4 CHECK THE LUMBAR MOTOR CIRCUITS FOR A SHORT TO GROUND
- Disconnect: Lumbar Control Switch C361.
- Measure the resistance between:
  - lumbar control switch C361-3, circuit CPS64 (BN/VT), harness side and ground.
  - lumbar control switch C361-7, circuit CPS65 (WH/GN), harness side and ground.
    
    Fig 4: Checking Lumbar Motor Circuits For Short To Ground
    Courtesy of FORD MOTOR CO.
- Are the resistances greater than 10, 000 ohms?
- Yes : GO to E5.
- No : REPAIR the circuit(s). TEST the system for normal operation.
  DISCONNECT the battery ground cable. CONNECT driver seat side air bag module C367. REPOWER the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM .

E5 CHECK THE LUMBAR MOTOR CIRCUITS FOR AN OPEN

Measure the resistance between power lumbar switch C361, harness side and power lumbar motor C366, harness side, using the following chart:

Power Lumbar Switch	Circuit	Power Lumbar Motor
C361-3	CPS64 (BN/VT)	C366-1
C361-7	CPS65 (WH/GN)	C366-2

Fig 5: Measuring Resistance Between Power Lumbar Switch C361 And Power Lumbar Motor C366

Courtesy of FORD MOTOR CO.

Are the resistances less than 5 ohms?

Yes : INSTALL a new lumbar control switch. REFER to LUMBAR CONTROL SWITCH . TEST the system for normal operation.
DISCONNECT the battery ground cable. CONNECT driver seat side air bag module C367. REPOWER the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM .
No : REPAIR the circuit(s). TEST the system for normal operation.
DISCONNECT the battery ground cable. CONNECT driver seat side air bag module C367. REPOWER the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM .