Why does the build warning light come on your Volvo 940 1994 every time you press down on the brakes when all brake bulbs are working okay?

* It about a difference in electrical flow in the left and the right circuit.

* If you replace your bulbs per one instead of per pair then there is mostly a difference in electrical resistance in both bulbs. If the difference is to great the warning light comes up.

* If you lights are always from te same age then it could be that there is corrosion in one of the the bulb holders is.

If the warning lights comes up when you use the break then it is obviously that one of the arguments above is valid. Start with replacing the bulbs and to check if there is corrosion. Keep the break on and sligtly move the bulbs with a left/right twitch. This will refresh the contact. If the light goes of it was a bad contact due to erosion.

JH