Hardwiring Radar Detector Failure - What am I doing wrong?

[scyrusurcys]

I'm trying to hardwire my Escort 8500 to my '95 540i. The radar detector itself is functional; I can plug it in with the cigarette-lighter adapter and it powers on fine.

As for hardwiring, I have the positive wire going to the vanity lights that turn on when you flip the mirror shade open on the driver's side (connected to metal clasp that holds the bulbs in place, electrical hot spot). I have the ground wire connected to the OEM ground wire that the center interior lights is ran from (I cut the wire and spliced it). Both of these connections are 12v connections. So even when they're connected, the radar detector does not turn on. I double-checked with a circuit tester and they successfully complete the circuit. The fuse that's included within the positive wire is also still good.

What gives?

[nismoracer65789]

did you follow this guide?
http://www.bmw4life.com/radarDiy.htm

[E34ührer]

Are you using the 'smart cord' or just power and ground? If you are using a smart cord, make sure to check the connection at the unit, and also check for continuity from one end of the cable to the other...those smart cords are notorious for broken wires in the cord.

For sure you have 12V at the connection?

I would try using a different wire for power. Use a t-tap on one of the map lights up front to just verify it works.

[mtg729]

Those lights only work when the headlights are on. IIRC

Find a new positive that is always hot and your set.

[bblazen]

Those lights only work when the headlights are on.

Find a new positive that is always hot and your set.

Would you happen to know of one :stickoutt I would like to to this tomm

[mtg729]

Would you happen to know of one :stickoutt I would like to to this tomm

Sunroof switch.

[bblazen]

Sunroof switch.
;)

[moroza]

Sunroof switch is a good one but I'd be concerned about frying something if you try to use both at once.

I ran wire from my rear cigarette lighter (in hindsight, front would've made more sense as it's the same circuit) and never had a problem.

[scyrusurcys]

did you follow this guide?
http://www.bmw4life.com/radarDiy.htm

I read the guide 2 or 3 times before I tried the installation. My only hesitation was tapping into the ground wire of the sunroof switch. The wire for my radar detector looks like a 12 guage wire while the sunroof ground wire looks to be about a 16 gauge. Being electronically new, I didn't know if that would cause problems, so I chose to ground it to a larger wire (center interior light ground).


Those lights only work when the headlights are on. IIRC

Find a new positive that is always hot and your set.


From my circuit tester, it indicated that the wire was hot when the key was turned to ACC, even without the vanity lights or the headlights being on. I'm only assuming that opening the mirror shade connects the ground wire to complete the circuit, turning them on. I'll T-tap into the sunroof switch ground today to see if anything happens.

[4500 RPM]

Passenger vanity mirror was what we tapped into. You can use that light and have the detector on without blowing a fuse or melting anything.