[s-cars] RE: Lobotimizing the Lamp Control Module - More

[Paul Gailus]

If you're willing to lobotomize the module, then you should be
able to get by with a fix that takes quite a bit less current.

Like Mark says, it looks like they are using the voltage drops
developed across some low resistance PC board traces to detect the
presence of headlight current.

I'm sure that there's a voltage comparator that "tells" the lamp
controller that there's a good headlight present, as long as
there's at least a certain minimum voltage drop across the trace
(in other words, there is a detection threshold voltage).

So if you're willing to cut the serpentine board trace
and solder a larger value resistor across it, you can draw
a lot less current from the module and still develop enough
voltage drop to fake out the module.
You might start by trying 2 voltage divider resistors that
would give you about a 100mv to 200mv drop.
It's possible that you could even ground the headlight
end of the trace and fake out the module without
any resistors (after cutting the trace). However, I would
not do this because it could overly stress the input
devices of the comparator.

Paul

----- Original Message -----
From: Mark Strangways <Strangconst at rogers.com>
To: Sean Douglas <quattro20v at telus.net>; <HAHNMGH63 at peoplepc.com>
Cc: <s-car-list at audifans.com>
Sent: Monday, October 11, 2004 11:09 PM
Subject: Re: [s-cars] RE: Lobotimizing the Lamp Control Module - More


> Thought I had, in previous e-mail...
>
> But, if the fact that the auto-check is showing a burnt out headlight(s)
> then you *should* be able to add a resistor 9.6 Ohm x MIN 15 watt. in
> PARALLEL to the ballast power supply. This will not do anything good for
the
> start-up in rush current (will add 1.25 Amp), but should bring the current
> draw to the bulb monitor box specified range.
>
> Since I don't have HIDS (yet), it's only theory, but should work. If you
> relay them then you will have bigger problems on your hands. Use a 3.7 ohm
> resistor (4 may work) in parallel to your relay COIL. You will need MIN.
50
> watt rating ($$$$$)... don't use anything smaller or you will let the
smoke
> outta it ;-)
>
> Mark S
> ----- Original Message -----
> From: "Sean Douglas" <quattro20v at telus.net>
> To: "'Mark Strangways'" <Strangconst at rogers.com>;
<HAHNMGH63 at peoplepc.com>;
> "'Igor Kessel'" <KBATPO at comcast.net>
> Cc: <s-car-list at audifans.com>
> Sent: Monday, October 11, 2004 11:47 PM
> Subject: RE: [s-cars] RE: Lobotimizing the Lamp Control Module - More
>
>
> > The resistor fix sounds interesting, can you elaborate?
> >
> > Sean
> >
> >
> > > -----Original Message-----
> > > From: Mark Strangways [mailto:Strangconst at rogers.com]
> > >
> > >
> > > Looks like on your board they are using back and forth
> > > weaving traces to establish a micro voltage drop across. But
> > > with out getting my hands on it I have no idea.
> > >
> > > For what it's worth , a pair of resistors may be a cheaper
> > > easier fix. Just make sure you get 15 Watt minimum rating.
> > >
> > > Mark