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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-0034: Front 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 cable between the control module and the roof lamp unit. Check for a short-circuit to ground.

Remove the connector from the roof lamp module and measure between the connector and the upper electronic module (UEM) as follows.

UEM-0034 Left front reading lamp 

Control module terminal #20 and roof lamp module terminal #3A.

UEM-0036 Right front reading lamp 

Control module terminal #20 and roof lamp module terminal #4A.

Check the cable between the control module and the roof lamp unit. Check for an open-circuit.

UEM-0034 Left front reading lamp 

Control module terminal #18 and roof lamp module terminal #3A.

UEM-0036 Right front reading lamp 

Control module terminal #6 and roof lamp module terminal #4A.

Replace the cable if a fault is found.

If the cable is OK, try a new bulb in the roof lamp module.

Other information: 

Fig 1: Identifying Connector Terminals
GLL104043Courtesy of VOLVO CARS CORPORATION
Fig 2: Identifying Ohms Display
GLL101042Courtesy of VOLVO CARS CORPORATION