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Mercedes-Benz C-Class: How to Hardwire Radar Detector

Unsightly wires are the worst thing about having a radar detector. Learn how to hard-wire a radar detector in your C-Class, saving you from ever having to see them again.

By Jared Hammond - May 15, 2015
Contributors: jmueller, superlubricity, cyberorth

This article applies to the Mercedes-Benz C-Class (2007-2014).

A radar detector will give you a warning whenever a radar is pointed towards your vehicle. Installation in your C-Class is relatively simple; you just mount it to the top of your windshield and plug it in. But this leaves an unseemly wire hanging over your dashboard. Instead, try hard-wiring your radar detector to your car. The steps below will show you how to do it yourself.

Materials Needed

  • Radar detector
  • Wire cutter/stripper
  • Soldering iron and solder
  • Electrical tape
  • Plastic card
  • Multi meter

Note

Disconnect the car battery before you begin.

Step 1 – Open the map light compartment

Take a credit card and slip it in the gap in front of the middle of the map light. Press it in until the compartment pops open.

Figure 1. Opening the map light compartment.

Step 2 – Route the wire through the headliner

Pull the wire for your radar detector through the headliner on the passenger's side to the edge of the dome light compartment. Cut out the end near the dome light and strip away a bit of the cover.

Figure 2. Thread wire through headliner.

Step 3 – Connect the wires

Pull out the second of the two blue electrical harnesses in the dome light compartment. Look for the red wire with a black stripe on the right hand side of the connector when looking at the wires. There's more than one wire of that color so don't get them confused. Strip off a bit of the wire cover and solder the end of your radar detector's power wire to the dome light wire. When they are soldered together, wrap the connection in electrical tape. Next, find the brown wire in the top left pin of the connector. Solder your ground wire to this wire and route it to the nearest grounding point.

Figure 3. Arrow points to the connector and red wire.

Pro Tip

If you are uncomfortable with modifying factory wires, you can try attaching an adapter to the plug in the glove compartment and routing the detector wire from the plug, through the cover of the A-pillar to the headliner, but be careful to avoid the airbag at the top of the A-pillar.

Step 4 – Mount the radar detector

Mount your radar detector to the windshield. The higher you mount it, the better range it will have, so place it near the rear view mirror. Connect your wire under the headlining to the detector. It should now turn on whenever you start the car and go off after you've locked the car. Spend a couple minutes testing it; if it doesn't come on at all, then there could be something wrong with the wiring. When you're finished, stuff all the loose wiring back into the map light compartment and snap the compartment back into place.

Figure 4. Mount the radar detector.

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