Lighting system data can be read from the Data Link Connector 3 (DLC3) of the vehicle. When the system seems to be malfunctioning, use the intelligent tester to check for malfunctions and perform repairs.
Check the DLC3 Click here.
INSPECT AUXILIARY BATTERY VOLTAGE
Measure the auxiliary battery voltage with the power switch off.
If the voltage is below 11 V, recharge or replace the auxiliary battery.