BMW 650i Headlight Bulb
Troubleshooting Common BMW 650i Headlight Bulb Problems
The headlights of your BMW 650i are actually made up of several components, and at the heart of it all is the headlight bulb. Most 350i coupes are fitted with a composite halogen bulb, which can last anywhere from 1,000 to 2,000 of use depending on the environment the bulb is used in as well from as a variety of factors. And when they do give out, busted headlight bulbs can pose a serious safety risk. Luckily, symptoms of imminent headlight bulb failure are easy to spot. The following are some of the common signs that your BMW 650i headlight bulbs are starting to fail and how to troubleshoot them.
One bulb doesn't work
A headlight that doesn't light up is a good indication of a busted headlight bulb, but it's just one of the many reasons why the headlight won't work. First, check if the electrical connections at the back of the headlight assembly are loose or damaged. Next, check if the headlight bulb socket is loose or corroded. If the both the wiring and the socket appear to be in good condition, check the bulb itself to see if it is burnt out and replace it if necessary.
All of the bulbs don't work
On the other hand, if both headlight bulbs aren't working, the problem is likely to be with the fuse. Open the 650i's fuse box and inspect the main fuse for the headlight circuit. If the fuse has blown, replace it with a fuse of the same amp rating. If the new fuse blows immediately after installation, there might be a short in the headlight circuit that needs to be repaired.
The bulb emits a dim light.
If the headlights appear to be dimmer than usual, especially when you press on the gas pedal, there might be a problem with the alternator. With the engine idling, check the charging voltage with a voltmeter; if the headlight is working properly, the meter should display 13.5 to 14.5 volts. However, if the meter displays anything less than 13 volts, there's likely to be something wrong with the alternator.