[V8] Remoting the Headlamp Sensor Module for Headlight RelayUpgrades

CB&D, LLC cbdllc at ntelos.net
Thu Nov 10 07:52:30 EST 2005

"unfortunately that's the way it has to be since you are
powering the headlights from under the hood."

If you were relaying the headlight supply from under the hood, it
would seem that the output side of the light control module (pins
8/58BL2 and 2/56BR1) are now connected to the new/added headlight
relay coils.

Maybe it is possible replace the supply coming from the headlight
switch on 4/56L and 6/56R with a larger one.  Then the coil for the
new/added relays could be located with the aux. relay box and
powered by 4/56L and 6/56R, instead of 8/58BL2 and 2/56BR1 under the

The relays would then switch the newly installed supply into the
light control module.  This would allow the light control module
wiring along with all headlight wiring under the hood to remain

Am I making any sense or am I totally off track?


-----Original Message-----
From: v8-bounces at audifans.com [mailto:v8-bounces at audifans.com]On
Of Buchholz, Steven
Sent: Wednesday, November 09, 2005 8:03 PM
To: v8 at audifans.com
Subject: [V8] Remoting the Headlamp Sensor Module for Headlight

... this is one of those projects I'd like to document fully ...

Basically you are half way there by jumpering the module in the fuse
block ... unfortunately that's the way it has to be since you are
powering the headlights from under the hood.  What you do is to
the module you pull out of the fuse box in the relay panel.  There
two circuits for the low beam lights ... wire them up just like they
from the wiring diagram ... wait, I've got the wiring diagram here,
me get some pin numbers.  The only odd thing that you will need to
do is
to run a single sense wire back to the fuse box and plug it into the
location in the socket where the sense wire would connect.  I've
actually been able to snake a Teflon insulated small gauge wire back
through the harness ... no BTDT for the headlight sensor
yet ...

The module in question is labeled J123 and is called "Lamp Control
Front" and is located in position 7 in one of the aux relay panels.
module works by measuring a difference in the voltage drop across
low value resistors, which means the current for the bulb has to
through the module on the way to the lamp.  The pin labeled 4/56L is
supply for the left headlamp bulb, and the associated lamp is
to pin 8/58BL2.  The supply for the right headlamp comes in on pin
and the bulb attached to pin 2/56BR1.  Pin 7/31 is to be attached to
ground.  The last pin on the module is pin 9/K.  This is the wire
need to route back to the relay panel ... although it looks like you
could also intercept at a Kostal connector (T14i/4).  I would simply
crimp the appropriate male spade lug to the end of the wire fed back
plug it into the relay panel where the pin (9/K) would have been
attached were the module plugged in.  Of course you will need
from pin 4/56L to 8/56BL2 and 6/56R to 2/56BR1 to supply the signal
needed to enable the relays with the headlight switch.  A preferred
situation might be to find a similar module and use the base as a

Steve B
San Jose, CA (USA)
> Could you describe this process?   On my cars with relayed
> used the jumper-replaces-relay "fix" that does not leave you with
> sensor function.
> At 12:50 AM 11/9/2005 -0800, urq wrote:
> >... for all the hassle you have to go to for installing the
Euros, it
> >really that much more difficult to relocate the warning module to
> >headlight relay box and retain the functionality of the sensor

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