Electrical: - Bulb failure light

JJKM · Apr 10th, 2014, 23:47

A short time ago, I had my bulb failure relay suddenly burn out with a cloud of smoke. I have recently replaced it and now, whenever I push the brake pedal, the sensor light comes on; any suggestions as to why?

Thank you!

migrator · Apr 11th, 2014, 08:39

The 'bulb failure warning' light is activated by the 'reed switch' relay device and the tolerance of these devices can differ. What appeared to be 'OK' from one device can trigger the warning light from another of the devices.

There is an assumption here that you have checked all of the brake lights and that they are all operating. If there is a difference in drawn current between the right side of the car and the left side of the car there is the potential for the warning light to be powered. Different brands of bulb of the same wattage can draw down different amounts of current and this will trigger the warning light. One old light and a newer light from the same manufacturer can draw differing current. A bad earth connection for one of the bulbs (including the high level light if fitted) can also be a cause for the trigger.

You indicate that the original relay burnt out and the fault within the relay could have been masking the current problem.

Apr 10th, 2014, 23:47	#1
JJKM Member Last Online: Apr 3rd, 2022 22:39 Join Date: Jul 2013 Location: Dover	Bulb failure light A short time ago, I had my bulb failure relay suddenly burn out with a cloud of smoke. I have recently replaced it and now, whenever I push the brake pedal, the sensor light comes on; any suggestions as to why? Thank you!

Apr 11th, 2014, 08:39	#2
migrator Aye - him again Last Online: Today 16:23 Join Date: May 2001 Location: HAWICK	The 'bulb failure warning' light is activated by the 'reed switch' relay device and the tolerance of these devices can differ. What appeared to be 'OK' from one device can trigger the warning light from another of the devices. There is an assumption here that you have checked all of the brake lights and that they are all operating. If there is a difference in drawn current between the right side of the car and the left side of the car there is the potential for the warning light to be powered. Different brands of bulb of the same wattage can draw down different amounts of current and this will trigger the warning light. One old light and a newer light from the same manufacturer can draw differing current. A bad earth connection for one of the bulbs (including the high level light if fitted) can also be a cause for the trigger. You indicate that the original relay burnt out and the fault within the relay could have been masking the current problem. __________________ (Ouch - that's another knuckle ...) VOC 11817

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