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bulb check defeat / headlight relay harness
greg amy (and maybe others) were asking about how to defeat the bulb check
warning after installing a lighting relay harness. i had archived this post
from john karasaki (with thanks to others) that explains most everything in
It has been about a month now since I've installed the Competition Limited
wiring harness in our 1990 V8 quattro. The light output is awesome! The CL
kit allows all four lights (2 high beam and 2 low beam) to be on at the same
time. High wattage 9005/9006 lamps (100w/80w) can be used as well since the
kit is equipped with relays to direct power directly from the battery post.
Almost all current is removed from the headlight switch. This is an added
benefit as the power consumed by the stock headlights are at the limit of
the contacts in the OE switch.
The light output is better than the 5k single H4 lights I've used on our
5ktq and the H4/H1 one piece headlights on our '82 urq. I am still amazed.
The people at CL are conservative in their marketing; I received conflicting
comments from the different sales people there. The woman I spoke with
(Mrs. Henderson) was the most helpful. If you are going to order a kit,
just tell them you want to buy their kit for cars equipped with 9005 and
9006 lamps. I wouldn't even mention that you have an Audi V8. They might
waste your valuable time telling you that: a) They don't sell a kit for this
car. And/or b) You have to put electrical tape over the warning display in
the instrument cluster to defeat the lamp check circuit. Neither is true.
I installed the generic 9005/9006 kit in about an hour without cutting a
single wire! Using a pocket knife to scrape the paint off the frame rail
(under the winshield fluid container screws) on the passenger side (right)
to get a good ground took the longest time. If you have a Dremel tool this
will take no time at all. On the driver's side (left) I used the brake
pressure accumulator to frame mounting point to ground the lamps on that
side. I could have used another spot, but I didn't want to extend the wires
as I wanted to be sure that this kit was truly all you needed to complete
As this is a generic kit for many different makes of cars, all four lights
did not come on when I first finished the installation. Just follow the
trouble shooting instructions for the GM cars. EXCEPT, DO NOT CUT the wires
as instructed! Rather, the female spade connectors in the lighting
connector can be removed and their position swapped using a very small
(eyeglasses repair type) screwdriver. If you haven't worked with these type
of female connectors before, it may take a little patience while you figure
out how to release the tab that holds it in the connector. From the front
of the connector, insert the screwdriver into the spade slot (between the
spade back and the plastic) while pulling on the wire from the other side.
By trial, error and probing, it will eventually slide out. Be patient!
Another note: Follow the GM instructions NOT the Maxima, BMW, Mitsubishi
instructions. The diode box must be installed.
This is a "must do" modification for the V8 owner! If you can hang
Christmas tree lights, you can install this kit. I haven't given much
detail because there is not much to discuss and the instructions cover
everything I haven't mentioned. I, too, had many questions that were
immediately answered once I had the kit in hand. Again, I did not cut a
single wire to install this kit. It truly is a plug and play operation.
I didn't buy my lamps from CL. They supply the same Korean brand I found
locally for half the cost.
Below, I've attached the e-mail sent to me that details how to defeat the
lamp check system. The instructions are very detailed. Many, many thanks
to the author! Thanks also to Eliot for providing the inspiration.
BTW, the entire project, including lamps and shipping cost less than $90.
This includes the 20% harness discount I received for buying two lighting
kits from CL. This is the same discount that they give if you buy one kit
AND the lamps from them.
INGO's post follows:
Just a quick note to say "Thank You" to Igor Kessel and Al Powell for their
Low Beam Headlight Warning display solutions. I ended up using Al's
solution, since I didn't have a spare relay to work from and it worked just
as promised for the V8. On the V8 the relay is located under the pass
How to get to relay for V8:
1. Remove pass side (US) insulated base carpet. Put seat all they way back.
2. Remove fuse panel carpet on right side of pass footwell (unscrew two
knurled knobs holding carpeted panel in place.
3. Remove two screws attaching center console carpet to relay box (where
your passenger's feet would be) and pull carpeted panel by center console
downward and away from tunnel.
4. Look over diagrams on relay box. One is labeled lamp warning, I believe
(no. 7). The V8 has a unique way of cramming all its relays through sliding
trays which you will see shortly. Remove two more screws (one at top of
cover, the other on right bottom, and remove.
5. Slide out(pull) top (in my case) shelf as indicated by relay diagram, so
that relay tops are facing you. The "culprit is marked "281" aka 443 919
6. Take four spade connectors(blue ones if insulated at the hardware store)
and six inches of 14 ga. wiring, cut to make two 3" pcs. and crimp
corresponding spade connectors . I removed spade insulation for better
crimping and then put heatshrink tubing on exposed surfaces. Don't know how
diagram will come out, but here's how wires plugged into my relay socket (\
and / indicating 3" 14 ga wires, == and II indicating spade connector
II 56bR II 56bL
Very logical, but remember, always double check before testing. Test and
reassemble minus relay. Any additional questions, check out Igor's earlier
post or Al Powell's response from January 1, 1997 entitled "Keeper:
Defeating Headlight Warning."
Audi Quattro Fanatic