Checking contact resistance, oxidation and wiring

Check the carphone box and keypad unit/carphone module MBUS connectors for loose connections according to Loose connections (terminals) .

Check the wiring between carphone box #C7 and keypad unit/carphone control module #B7 for a short-circuit to ground according to Short-circuit to ground, intermittent faults .

Remedy as necessary.

Other information: 

• To access/replace the carphone box, see Carphone box .
• To access/replace the keypad/carphone module, see Radio/carphone, replacing .
• To connect the breakout box, see Connecting the breakout box, Carphone module .
• For information about signals and connectors, see Keypad unit / Carphone module (PHM) (to carphone box) and Carphone box (to keypad unit / carphone module (PHM) .

Fig 1: Identifying Breakout Box

Courtesy of VOLVO CARS OF NORTH AMERICA.

Fig 2: Identifying Ohmmeter

Courtesy of VOLVO CARS OF NORTH AMERICA.