Intermittent indicator

The modern addition of Can-bus controlled lighting on many vehicles means that, when a bulb blows, the system can substitute another bulb in the same area to act in its place. The dash display of this 2002 Mercedes SL500 was showing its owner that two bulbs were inoperative – one was a rear side-light, the other a front indicator. The rear side-light had substituted a brake light bulb fed at a lower voltage, while the front indicator had substituted a fog-lamp.

Replacing the blown side-light bulb rectified the problem at the rear, but the front indicator bulb appeared to be in good order. The problem here was the bulb holder, which had a burnt contact point. Wiggling the bulb holder in the lamp would temporarily restore the indicator operation, but the more permanent solution was to fit a new bulb holder.

The contact point on the bulb holder had burnt through due to a poor contact.