Checking For A Short-Circuit

Check that the button has not jammed in its depressed position.

Check the cable between control module terminal #16 and roof lamp module terminal #7A. Check for a short-circuit to supply voltage.

Check the cable between control module terminal #4 and roof lamp module terminal #8A. Check for a short-circuit to supply voltage.

Replace the cable if a fault is found.

Other information:

For further information about signals and other values, see SIGNAL DESCRIPTION, UPPER ELECTRONIC MODULE (UEM)
To connect the breakout box, see CONNECTING THE BREAKOUT BOX
To access the roof lamp module switches, see INTERIOR LIGHTING, REPLACING
To access the connector for the upper electronic module (UEM), see UPPER ELECTRONIC MODULE (UEM)/REARVIEW MIRROR, REPLACING
With the ignition on and when the function is not activated, the voltage between terminals #7A and #8A and ground should be 0 V
see CHECKING WIRING AND TERMINALS .

Fig 1: Identifying Connector Terminals

Courtesy of VOLVO CARS CORPORATION

Fig 2: Identifying Voltage Display

Courtesy of VOLVO CARS CORPORATION

Was a fault detected?