Checking the operation of pushbuttons and manual controls
Symptom: Seat cannot be operated in certain positions. No diagnostic trouble code. One of the "Read switches" in the ISAT shows "Open".
 
  
 
 
  
   
    
     |  | Checking the operation of pushbuttons and manual controls | 
   
  
  
  
   Fault symptom:
  
  
   
   
  
  
  
   
    
     
      | • | Seat cannot be operated. 
 
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      | • | No diagnostic trouble code. 
 
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      | • | All "Read switches" in the ISAT show "open". 
 
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    Diagnostic procedure:
   
  
  
   
   
  
  
  
   
    
     
      | 1. | Check that the control module is supplied with power,   
 
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      | 2. | Unplug the control module's 16-pole connector and plug in a BOB. 
 
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      | 3. | Check that a supply of about 12 V is present across pin 8 and chassis ground. If it is not  . 
 
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      | 4. | Measure the voltage across pins 8 and 9. It should be about 12 V. If it is not, check the ground cable (pin 9) for continuity/shorting. 
 
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    Fault symptom:
   
  
  
  
   
    
     
      | • | Seat cannot be operated in certain positions. 
 
   
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      | • | No diagnostic trouble code. 
 
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      | • | One of the "Read switches" in the ISAT shows "Open". 
 
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    Diagnostic procedure:
   
  
  
  
   
    
     
      | 1. | Unplug the control module's 16-pole connector and plug in a BOB. 
 
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      | 2. | Connect the BOB between pin 8 and the following pins, depending on the fault: 
 
 
        Pin 7 - memory button 1 Pin 6 - memory button 2 Pin 5 - memory button 3 Pin 16 - memory button M
        
        If entire functions are inoperative, check the wiring between pin 8 of the control module and pin 1 of the pushbutton assembly.
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      | 3. | Connect a jumper lead between pin 8 and 
 
   pin 1 - backrest upright 2 - backrest recline 3 - front down 4 - front up 10 - rear down 11 - rear up 12 - seat forwards 13 - seat rearwards
 
 
   
 
        If the seat moves as desired, change the pushbutton assembly or the switch assembly.
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      | 4. | If the seat does not move, check the wiring between the switch and the control module for continuity/shorting. 
 
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      | 5. | Turn to page 852-55, "Before control module replacement". 
 
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