If the electrical system on your car appears to have a mind of its own, this can be very disconcerting. You may be scratching your head if you select the indicator switch, only to find that the interior light comes on instead. In this case, it looks as if you may have a short circuit, so what is going on and what should you do next?
The electrical system on your car is quite complicated and will rely on individual sensors, switches and relays connected by automotive-grade wires. Hundreds of individual wires run from the engine control unit (ECU) to each particular component and they are typically grouped together through bulky wiring looms. It's not unusual for engineers to include dozens of individual wires in a single loom and they're usually colour-coded so that electricians can readily identify them.
How Short-Circuits Develop
If the wiring loom is mounted to the underframe of the vehicle or has to loop in or around other obstacles, then it may be vulnerable. The mounting points may move to a certain extent when the vehicle is driven over an uneven surface or may be susceptible to dirt, debris or moisture. Over time, the outer surface of the loom may deteriorate, and this can affect the wires within. When this happens, the outer protective surface of each affected wire may chafe, and this may cause two wires to touch together. In your case, the wire that leads to the interior dome light is adjacent to the wire that activates the turn signal. When you activate that signal, power is sent to the dome light as well, and this is the cause of your confusion.
However, remember that this is not just an inconvenience, as it could be potentially dangerous. A short circuit like this could cause the plastic sheathing to burn, and this could set light to other flammable parts in that area. As a consequence, you need to take action as soon as possible.
Bringing in the Electrician
As there are so many wires and they are often difficult to access, you should turn over this task to a qualified electrician. They will have certain tracing tools that will help them locate the problem area and, once they have done so, they'll be able to repair the protective coat. If need be, they will remount the wiring loom, so that it is not vulnerable to damage in the future.
Check out an auto electrics business to learn more.