Power for your Radar Detector

I was looking to find a way to hard wire a power connection for my Valentine One radar detector. I had already read through Richard Carlson’s “cutting the cord” article so I felt familiar with the task at hand. This was a great resource, and I recommend you read it first because he has excellent instructions at how to get the plastic panels off, as well as some good warnings. However I wanted the power source to drop from top of the A-Frame rather than up through the dash. The MZ3 has enough room above the rear view for the V1 to slide into (click on the picture for a larger view).

First, a quick lesson about BMW wiring. Turns out that everything is color coded, which makes finding a power source a little easier. Red wires are unswitched power sources (on all the time). Purple (with white stripe) wires are switched power sources (on when the car is on). Brown wires are ground. Depending on which type of power source you want you can choose which wiring harness to use.

The information below is specific for the M roadster’s, it has come to my attention that the wiring on the 1.9 and 2.8 roadsters is different. The color coding is the same but wiring harness locations are different. If you own a 1.9 or 2.8 you’ll want to focus on the area behind your stereo, tapping into its switched (purple and white wire) power source.

A couple M owners spoke with me after using the information below. The first spent about 45 minutes to an hour and commented that everything was straight forward. Thought he could do the job again in less time. The second M owner that spoke to me said the wiring was straight forward but the black plastic trim pieces (under the dash) gave him a lot of trouble. I think he summed it up best by saying “I did it!, but you couldn’t pay me $100 to do it again”.

If you want an unswitched power source there is an unused power connector down by the drivers feet (click on the picture for a larger view). This connector has a positive and a negative unswitched power source. It is in a convenient location just below the speaker. To gain access to this area you will need to remove the lower kick panel and the panels covering the underside of the dash.

Problem was, I was in a picky mood and wanted a switched power source. Under the dash you can locate this connector (BMW calls it X223 – the connector is next to the 40amp fuse strapped to the MAIN wiring harness), it had 5 wires in the connector (click on the picture for a larger view). I know it’s hard to distinguish colors in this picture because of the flash but the left most wire is ground (brown) and the one next to it is switched power (purple with white stripe). In this picture the middle wire is pulled out of the connector (speed sensitive volume connection – another project).

The Valentine One radar detector came with a wiring kit. The black box in this picture is part of that wiring kit. Since this box wasn’t a BMW part the color scheme doesn’t quite match but the red wire out of the box was connected to the purple power source. The black wire was connected to a good grounding point (see the bolt and brown wires next to the speaker)

Once the connection was made all that was left was getting the wire to the radar detector. There was just enough of a gap on the side of the dash to slide a wire back to the corner (like using dental floss). Now the wire had made it to the top of the dash the A-Frame cover just pulls off and you can run the wire under the plastic cover. Along the top you don’t even need to pull off the plastic cover. There is enough of a gap to push the wire in where the plastic piece meets the window.

You should actually work backwards so you have just enough wire sticking out where the radar detector mounts, and bundle up any slack down below where it is easier to hide it.

If you are anywhere near Dallas and would like a trained BMW expert to do work like this for you, I can highly recommend Larry Nissen. Larry did the work on my car and took the time to explain everything for me.

Cutting the Cord

If you’ve got a Z3, chances are you’ve also got a RADAR detector. I’ve got an old BEL detector (no V1 flames please, I know Valentine makes the best detector, but the BEL does just fine for me). I’ve had two problems with the detector placement:

Trying to find a secure place where the detector doesn’t rattle

Trying to find a source of power for the detector

I solved the first problem by simply velcroing the detector to the dash. The problem then becomes the power source. I’ve had the car about four months now and I was getting tired of using the cord to the cigarette lighter. In addition to being unsightly and somewhat rattle-prone, the cigarette lighter is hooked up to unswitched power. This means you need to remember to shut the detector off and turn it on every time you leave and re-enter the car.

Not fun.

I originally thought I could tap into power easily, but it turns out to be quite an ordeal. I tried to get power from the main bank of fuses in the engine compartment, but could not figure out an easy way to run a wire through the firewall. Eventually, I decided to use the power from the head-unit of the stereo and a ground from the cigarette lighter. The job takes about three hours. You need to be somewhat handy, need a working knowledge of automotive electrical connections and must be small enough to crawl into the driver’s footwell. Here’s how you can do it too:

Before you begin.

Get a box or container which you can put the screws in. Figure out some way of labeling the screws, they are all different shapes and sizes. Also make sure you have the 5 digit radio code you will need to reactivate the radio. Expect the job to take 2 to 3 hours. READ ALL DIRECTIONS FIRST!

You’ll need:

a phillips head screwdriver

a wirecutter

two tap-in connectors (Radio Shack 64-3052A)

several miniwire clips (Radio Shack 278-1668)

several connectors (optional – Radio Shack 64-3049A)

a 2mm allen or the BMW tool (a 5/64″ hex key)

at least 2 replacement BMW screw head covers

a seven foot wire to run from your detector to the power source

a white, dry-cleaners type coat hanger

electrical tape

a multimeter (optional,

lots of patience

First prepare the car by taking it apart.

Take the top down.

Look in the driver’s footwell and find two small rubber heads securing the front of the console.

Remove the rubber heads by hooking them with a stout paperclip-end from the bottom (the part that faces down). You should be able to hook them then pull out to remove them. They will resist. Be persistent. This will expose the screw head.

Remove the upper screw first, label it “upper”. Then remove the lower, label it “lower”. (Yes, they are different sizes)

Remove the radio:

Be sure you have the 5 digit reset code to reactivate the radio before you disconnect it.

Flip open the two small doors on either side of the radio to expose a small allen nut (It’s actually not an Allen nut, BMW sells a $16 tool to unscrew it, but a 2mm Allen wrench worked for me).

Screw the nut counterclockwise until it stops.

Repeat with the other allen nut

gently pull the radio towards you.

At the back of the radio, remove the antenna plug

Use a screwdriver to gently push up the “locking collar” for the other connections. It goes up about 1/2 inch, but does not come off. If you do this successfully, the entire back plug unit will come off. Otherwise, gently rock the entire connector back and forth, pulling backwards to remove it.

The radio is now disconnected.

Remove the shift knob by pulling straight up – be careful! You can hit yourself in the nose when it comes loose!

Remove the shifter boot – same process as the hand brake (except the “clips” are on the sides).

Remove the foam collar which surrounds the shift knob (Take a minute to note how it goes back in)

Push from below to pop the lighter out

Crawl under the driver’s dash – you will what looks like two large, black screw heads.

Rotate them 90 degrees and they should fall out.

Now remove the large plastic piece which goes around the pedals. You’ll need to pull it “backwards” (towards the back of the car), then push forwards again to get it loose. I ended up fighting with it for quite a while, but it eventually comes out.

Next, run the wires from the detector to the power source.

Cut the dry-cleaner’s hanger into a bent piece about a foot long. You’ll be using it to snake the wires through the defroster vents

Sitting in the Driver’s seat, start at the right most of the driver’s vents and manipulate the hanger till it comes out of the left most vent.

Tape your detector power plug (connected to the cord) to the hanger and snake it back through the holes.

Use one of the mini-clips to secure it to the dash. This prevents the cord from falling into the vents when not in use.

Run the rest of the wire to the A-pillar.

You can just push the wire into the crack which leads to the door.

Just below the console, pull the trim from the door-sill to allow you to run the wire into the console.

Put the trim back into place

Run the wire along the bottom of the dash, securing it with the mini-wire ties.

Feed the wire up around the side of the center console.

Feed the positive lead to the opening for the head-unit.

Feed the negative (ground) lead to the opening for the lighter.

Now Connect the Wires

If you have plugged in your detector to see how it will fit with the wire you ran, please disconnect it now.

Disclaimer – I used a multi-meter to identify the source of switches positive power for the radio. It was the purple/white wire which leads to the plug. If you have a multi-meter, I would advise double checking on your car. BMW may change the wiring harness from year-to-year.

Use the Tap-in connector to connect the positive line to the purple/white lead of the radio harness. You should immediately hear a little voice telling you that you have just voided your electrical warranty.

Disconnect the lighter from the two wires.

Use the tap-in to connect to the brown (unshielded) lead which runs to the lighter.

If you have a multi-meter, turn the car to Accessory and check for proper power at the detector plug. If you don’t have a meter, you should plug in your detector (risking frying it if you have made the wrong connection).

Now put everything back together

Assuming everything went well with the detector test, you are now ready to close up the patient.

The cigarette lighter is tricky to get back in. Before reconnecting it and reinserting it, you must first move the orange collar from the top to the bottom of the unit.

You do this by pushing out (from the inside of the unit) on both the little “wings” at the same time. This requires a little manual dexterity or a lovely assistant.

Once you do this, you can move the orange ring down to the bottom of the unit:

Reconnect the wires to the lighter unit.

Insert the unit into the dash, aligning the small cutout on the left with the tab of the orange collar.

Press in on the collar, it will seat itself, then press the lighter in which will also seat itself.

Before putting the shifter back together, turn on the lights and make sure the small bulb which illuminates the lighter is still in place. If not, re-seat it (it goes to the right of the lighter when looking at it from above, it just fits into a small hole next to the lighter.)

Reinstall the foam collar, shift boot and knob.

Reconnect the head-unit and put it back into the dash, securing with the allen wrench.

Re-screw the console screws and put the new screw heads on.

Reinstall the foot-pedal guards.

That’s it! You can now connect your detector, it will turn on when the ignition is turned on. Now go find your cigarette lighter (or lighter plug) and put it back in! You’ve cut the cord!

Adding Motion Sensor to BMW Alarm

Here is what I did – it is fairly straight forward but please make modifications at your own risk.

The sensor I used came from Sound Conceptions – “www.autotoys.com”. The sensor is listed as “sensor: single zone perimeter sensor (radar)” and is $24.95 as of today (3/30/98). You can find it in the storefront – security section. It has three wires to hook it up – battery, ground and trigger. The wires are just long enough to reach where I mounted the sensor. If you want to experiment with different mounting locations, you may want to extend the wires.

For safety, unplug the BMW alarm harness at both ends before making any connections. I soldered and taped all connections.


connect this to the fused battery wire in the alarm wiring harness this is a yellow wire with an inline fuse. Connect to the alarm side of the fuse, thus the fuse protects the new wiring.


connect this to the ground wire in the harness – brown wire.


this will get connected to the hood switch sensor wire (white with red stripe) in the wiring harness. To avoid potential interference between the new and old sensor – I isolated them with two diodes. The diodes are 1N4001 which you can get at Radio Shack. Cut the existing sensor wire and splice in a diode with the cathode (banded end) toward the sensor – this sensor is active low. On the alarm side of this diode, add another with the banded side toward the new sensor – connect the new sensor trigger wire to the cathode of this diode. See the crude diagram below:

I mounted the sensor in the console just forward of the gear shift. Remove the gear shift boot and the foam insert. If you put just the hook portion of some stick on velcro tape on the back of the sensor, you can stick it to the carpeting under the console. You will want to play with the sensitivity adjustment on the sensor. I have mine currently set about 3/4 of the way to fully sensitive.

Performance is good but a little inconsistent. If someone sits in your car, the alarm will definitely go off. An arm reaching in will set off the alarm if the arm is moved around. Repositioning the sensor might help – the directions say the higher it is in the car the better.

Discuss this article and other Safety/Security upgrades in the

///MZ3.Net discussion forum.

Black Cars, Never Again

My very first vehicle was a black 1980 MGB special edition that my father purchased for me in 1984. I loved that car, and that old MGB had a lot to do with my decision to purchase the BMW roadster. However, I learned at an early age that black cars are always in one of two states. The first state is Clean the second state arrives an hour after you wash it Dirty. Sometime during the three years I owned that car I vowed not to own another black car again.

Flash forward to 1991 and we find Robert purchasing a brand new black Ford Explorer Sport. Somewhere between 1984 and 1991 I must have forgotten my vow. However, I took comfort with my decision by saying, “the Explorer looks so good in black, and hey it’s a truck, who cares if it’s dirty.”

Now flash forward to August 1996. A BMW salesman has just loaned me a Montreal blue 1.9 Z3 for the weekend, and it’s just too much fun. I decide I have to own one. Later in October of that same year I took delivery of a silver 1.9, remembering my anti-black vow and resisting to acknowledge how good the black BMW roadsters looked in the brochure.

By the following spring I had made many “Internet friends” on a BMW roadster message board. It was through this board that owners started noticing a trend that the black BMW roadsters seemed to be picking up more chips than the silver ones. The theory seemed to hold water, and was broadened a little to also include dark green in the “chip prone” category. People were trying to speculate why one color would be more prone to chipping than another color, but we really never came to a real conclusion. In my mind, I acknowledged that this theory might be true, but since we were just talking over the Internet it was hard to see the evidence.

Over Labor Day weekend later that same year, several of us drove to South Carolina for the first BMW roadster homecoming. It was there that we started re-discussing the paint chip issue. I saw with my own eyes Ulrich’s black roadster with lots of small paint chips on the hood. It was just as he described over the Internet, but it still wasn’t concrete evidence. I jokingly asked if he worked at a gravel pit, but the point was his daily route may be much different than mine. Despite all the evidence, I still couldn’t convict the black paint as “guilty”.

Flash forward to March 1998, I have sold the 1.9 to a friend and I am currently waiting to take delivery of a new 3.2 liter BMW roadster. While I am waiting for the new roadster to show up, the salesman is loaning me a 2.8 liter model so I can have the experience of driving each of the three engine configurations. As fate would have it, the loaner 2.8 turned out to be a freshly cleaned and waxed black roadster. The black looked really good as I pulled out of the dealership and it reminded me why black was such a popular color. Two days later I was already washing it, but it looked so good I really didn’t mind. One week and a thousand miles later the black 2.8 already had six very noticeable paint chips on the hood. The evidence is just stacked too high now; I am firmly convinced that the black paint is not only more prone to chipping, but the chips are also more visible.

I would strongly suggest that those considering the purchase of a BMW roadster avoid the black paint available on the Z3. If the lure of the black is just too strong, then I suggest you talk your salesman into throwing in some BMW touch-up paint because I think you are going to need it.

The 3.2 model has a different black paint, and while the jury is still out, it would appear that it is much better in regard to its durability. But it was my fear of the unknown that confirmed my color choice for the new roadster, Arctic silver.