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bulb detection by "canbus" light controller

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svizoman

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Hi,

I redone my stock halogen headlight to bixenon headlight and I redone the wiring as it is shown (I add a diode to enable high beam flashing durring daytime drive when only DRL are used).
Controller reports no problem for dipped beam bulb but high beam bulb is a problem.
1. If you turn off the lights (switch to position 0) and turn the ignition and then turn the lights on controler reports no error
2. If you leave lights on (switch to position auto) and then turn the ignition the controler reports high beam bulb error...
3. ... If you then turn the lights to off and flash high beam, high beam bulb error is cleared

Now I was wondering why is that and how to solve the problem.
If I understand correctly "canbus" controler detect burn out bulb by two measurments:
1. after ignition (bulb off) it sends some current through the bulb and measures voltage drop. If the bulb is ok then voltage drop should be minimum.
2. when the bulb is on it also measures voltage drop, but now it has to be in the right amount for 55W load. If it is not enough (let say 35W xenon ballast) is also reports the bulb error

So do you have any solutions, ideas....
 

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schmitt trigger

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Your description on how a canbus controller detects a missing or open bulb is correct.

What I've seen is that people add power resistors in parallel to "simulate" the load. A brute force solution and not very elegant, but it works.
 

svizoman

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Your description on how a canbus controller detects a missing or open bulb is correct.

What I've seen is that people add power resistors in parallel to "simulate" the load. A brute force solution and not very elegant, but it works.

One of the solution is resistor but "canbus" ballasts uses capacitor to simulate load. Capacitor drive current when "empty" and

I uses one of this "canbus" ballast and it work well, but problem is whit my high beam configuration. There are no error durring high beam since high beam current is feed to the ballast through diode, there are also no problem durring lights off since high beam is connected to the ballast (capacitor), problem is when I leave light to auto and dipped beam is active so high beam detection can't be done since current is flowing into the ballast from dipped beam wire.
What I was thinking is that I'll add extra capacitor between high beam + and ground.
 

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