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Home >> Volvo >> 2010 >> XC90 Base, AWD >> Repair and Diagnosis (Single Page) >> Electrical >> Body Electrical >> Rear Electronic Module (Rem) And Upper Electronic Module (UEM) Diagnostic Trouble Codes >> UEM-0030: Rear Left Reading Lamp. Signal Too Low (2003-2014) >> Signal Too Low >> Checking For Open Circuits And Short Circuits
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Checking For Open Circuits And Short Circuits

Check the wire between the upper electronic module and the control unit of the rear reading lamp unit for a short circuit to ground, as described in, see SHORT-CIRCUIT TO GROUND, PERMANENT FAULTS .

Remove the connector from the roof lamp unit and measure between the connector and the UEM as described below.

UEM-0030 Rear left reading lamp 

Control unit #20 and reading lamp unit #1.

UEM-0032 Rear right reading lamp 

Control unit #20 and reading lamp unit #7.

Check the wire between the upper electronic module and the control unit of the rear reading lamp unit for an open circuit, as described in, see OPEN-CIRCUIT, PERMANENT FAULTS .

UEM-0030 Rear left reading lamp 

Control unit #7 and reading lamp unit #1.

UEM-0032 Rear right reading lamp 

Control unit #17 and reading lamp unit #7.

If a fault is found, replace the wire.

If the wire is OK, test with a new bulb.

Additional information: 

Fig 1: Identifying Connector Terminals
GLL104091Courtesy of VOLVO CARS CORPORATION
Fig 2: Identifying Ohms Display
GLL101042Courtesy of VOLVO CARS CORPORATION