Check engine with trailer connected

[Huw Powell]

> I recently installed a trailer hitch and wired my '89 200 for a 6 wire
> trailer umbilical.  Whenever I connect the plug to the trailer, my Check
> Engine light comes on and indicates a brake malfunction.  I've been told
> by an Audi owner who tows a race car that this always happens and there
> is nothing one do about it.  Anybody familiar with this phenomenom and
> have discovered a way to have the trailer connected without lighting up
> the brake problem symbol?

I think... (and I don't know what the hell I am talking aobut here!) you
are running the trailer brake lights off one side of your cars brake
light circuit and the bulb check module is picking up the difference in
current and the only way it can tell you the "brake light is out" (which
of course it isn't) is to light up the brake warning light.  The module
senses a difference in current...

That's my theory, for what little it is worth.

The check engine light?  I haven't even got a harebrained clue.

All I know is if you pull (or blow) the fuse on my 90Q that runs the
interior lights, cig lighter, etc., the high beams and low beams both
run at the same time :-0

-- 
Huw Powell

http://www.humanspeakers.com/audi/

http://www.humanthoughts.org/