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Bulb-Out Light Winks[200/85] posted by Tony T. on
Saturday, 24 October 1998, at 11:26 p.m.
85 240 Turbo. When the brake pedal is depressed the "bulb out" light sometimes comes on for just a half second or so. No bulbs are burned out. Could this cause a problem? Is this normal? If not, any suggestions on the cure.
Thanks for any help!
Re: Bulb-Out Light Winks[200/85] posted by Stoney on
Sunday, 25 October 1998, at 1:20 a.m.
Check the brake light wiring in the trunk, the main bundle going to the left taillight can get disconnected or pulled partially out or if its a newer 240 series with the Printed circuit board the connector and wire can get corroded and the movement of the car can cause an intermittent short...If its a wagon then check the spare tire compartment...I had same thing on a 245 when the spare would shift and pull the wire bundle and the ground connector or feed wire wiould get bent on the spade lug and cause an intermittent signal...also check the bulb holder is seated correctly and remove it and clean the contacts...also check and clean the ground wire chassis connetion
Re: Bulb-Out Light Winks[200/85] posted by Don Foster on
Sunday, 25 October 1998, at 7:29 a.m.
Tony --
Stoney has a good suggestion worth investigating. I found the same thing on my '83.
Another cause is simply having two bulbs that aren't exactly the same. When you step on the pedal, the voltage goes to the bulbs -- and in that instant, the filament resistance goes from low to high as the filaments get hot and glow.
The resistance of the two bulbs is the same when they're on steady. But during the 1/2 second transition, the resistance differs, the "bulb out" sensor detects this difference, and the warning light briefly flashes.
This may be because the bulbs are from different parts of the world, different manufacturers, or are different ages.
One solution might be to buy a blister pack with two bulbs from the same manufacturer (maybe even the same production lot) -- these should have almost identical characteristics.
Another alternative is ignore the warning light -- providing you're sure the brake lights work. (That's my approach.)
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