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Failure sensing the three Brake Light bulbs 200 1989

uid 18083's pic
posted by  lucid on  Thu Jul 31 00:50 CST 2008
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last visit: Fri Oct 24 12:31 CST 2014
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"While the top mount brake light does run through the sensor, I'm not sure if it is part of the bulb out sensing system."


As you know, the basic BFS principle is that an equal current thru two opposing coils (having the same number of turns) will cancel each other, and thus have no effect on the reed switch inside the coils, which grounds the Warning light.

The 3-Light Brake Light test circuit is similar, except that the Left bulb is tested by one coil (say a nominal 20 turns), which is opposed by two coils end-to-end, nominally 10 turns for the Right bulb and 10 turns for the High Stop bulb.

As long as all three bulbs work, the 20t coil and 2 x 10t coils cancel out. However, a failure of any one of the three bulbs will upset the 20:20 "magnetic balance" and the reed switch will light the BF Warning light.





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New 1 Tail lights work but I get the bulb failure light [200][1989]
posted by  Justin A  on Tue Jul 29 08:51 CST 2008 >


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