I have a 2018 GS. I have a Uniden R3 with a blendmount with the power taps sold by them. Does anyone with access to wiring diagrams know where the fuse is for the purple wire in the inside mirror electrical harness? The purple wire has power only with the engine running on my car, but now it has no power under any conditions & I assume it is a fused circuit. The engine compartment fuse block has a fuse for the inside mirror, but it is not blown (I assume it is for the red power wire). I could not find any reference to another inside mirror fuse from the user manual.

At the moment I am connected to the red wire which is powered at all times. I would prefer to use the switched, purple wire connection that the purple wire would provide.

Thanks

 

Following is the most useful thread you'll find for the Blendmount/rearview wire tap installation:

https://www.corvetteforum.com/forums...n-2015-c7.html

 

I too would think the purple wire is fused. If that fuse is not blown it is very strange there is no power when the car is running.

The purple for hot and black for ground worked on both my 14 Stingray and my 18 GS. Its nice to shut the car off and have the detector power down.

Make sure your checking for power on purple with car running and on the part of the plug going into the head liner. Also, did you pull the fuse in the engine compartment and check it with it out of the car on resistance? I say that as some times they can read good in the circuit and still really be bad.

 

Thanks for your replies. Both of you offered relevant information concerning this problem. However, I did know that the purple wire is only hot with the engine running and in fact had it hooked with the tap (Black to black, Red to purple on plug out of the top windshield trim) and it worked. But after I reinstalled the cover onto the mirror it didn't work.
The cover did not go on easily. So yesterday, after taking the cover off I have no power to the purple wire with the engine running.

Here's where I am now:
1) No power to purple wire with engine running. (I do have a Fluke multi-meter with fine tipped probes and confirmed it attached to the plug coming out of the top of windshield frame, - Black wire, + Purple wire)
2) I confirmed continuity of the taps, through tap wire to the plug that plugs into radar detector, it's OK.
3) Confirmed the radar detector is OK and switched to the ON position on the detector.
4) Currently hooked up, - Black wire, + Red wire which results in always powered, have to turn detector on and off manually.
5) I can see no broken wires.

My reference to a fuse for the purple wire was concerning IF there was a fuse and if so where it might be. Maybe some one with access to wiring diagrams could answer that.
I plan on rechecking this today just in case I was making some errors due to it being a long day yesterday.

Thanks for your help guys!

 

This may or may not be a help. But this is what happened to me in October 2013 when there was no mirror tape available and folks said GM said they could not be tapped.

So I taped the passenger side, sun visor mirror light, as I had in my early Vettes. However as soon as the radar detector energized, power was gone. Thought I blew a fuse. Checked could not fine a fuse! In ~10 minutes power was back. Checked all my connections to be sure there was no short and the same thing happened when the radar detector was plugged in! Wound up using fuse 37 in the rear like others!

Turns out GM uses the computer to monitor current flow in some circuits and if excessive shuts off power to the device! At least that is what I was told by someone who said they have similar issues with new cars.

Have you checked after waiting some time?

Perhaps of no help, but I used a Blendmount wire tape for my 2017 Grand Sport.
But I connected this way:
Forum pics were a great help, particularly this one that showed where the Blendmount wires go, in the cable side from the car not that to the mirror. Negative black to Black Blendmount and the Red Blendmount to the purple wire as shown.


Best pic I found.



My Pic. Note: I did not take the plug apart, saw no need.

 

Thanks for looking at this Jerry.

I wired mine same as you show in your post. It did work with the same wiring as you show, but that was without the connectors attached to its cover and not installed on the rear view mirror mount. Attached the connector & cover to the mirror and it wasn't working.
I didn't have time to look at it today and presently my red tap is snuggling with the red & white wire, always on.
I put a cat heat shield on the oil tank side + another one on the oil filter side of my GS today. Was a beautiful day today, so I put some miles on my ride.
So, probably tomorrow I will take another look at that purple wire and with fingers ++ed it will be back powered with the engine on. Or if not go to plan #2.

Thanks again

 

^^

I did go thru several of the Blendmount wires to get one deep enough where the end did not bend. Enlarged the space with a dental pick and pushed in with small needle nose pliers. Also notched the plastic cover with a small round file so it wasn't pinching the wires.

Was a bit concerned that the wires would not hold when my Sticky Mount let lose! The Blendmount cord is about an inch or two shorter than would be optimum. I use a tether as I had in my 2014 C7 where I picked up power from fuse 37 in the rear. However in the year since I installed the ESCORT"Sticky Mount" (which came with the detector) on the Grand Sport it has fallen about 3 times and all is fine! If I park facing the sun on a hot day the partial vacuum in the suction cup reduces! In ~4 years it has never failed when driving. Looks like in the Grand Sport the detector weight is mostly held by the thin stainless tether! The Blendmount wires are still attached securely.

This is a PDF of my install FWIW: http://netwelding.com/Radar_Detector_Power.pdf


I like this mounting location as it does not restrict any vision. I added a thin stainless tether using a fishing leader. If the suction cup lets go, the detector and mount hang from a small eye hook! Has only occurred a few times in ~4 years when the car is parked facing the sun on a hot day!

 

 

 

Remember the purple wire isn't powered during accessory. It's only powered if the car is RUNNING (or if you hold the button for six seconds, that mode, which is easier to do for install purposes).

Fooled me too the first time around and I wound up running it to the battery because I couldn't find power in the mirror!

 

 

MTX-1010 is what I used. It's about 10 inches long with the taps plugged into the mirror tap wire and is just about long enough. If you are afraid it might not be long enough for you get the next size longer (15"), excess wire can be tucked up into the top windshield trim cover.
I did like Jerry indicated above (use link he provides). Using a round rat tail file I made a half moon hole on the left top of the mirror connectors cover (correct side for a Uniden R3), rounded any sharp edges left from filing to protect the mirror tap cable.
Make sure to locate the half moon cut so it doesn't interfere with the mirror connectors when they are inserted into the cover. With that done I could adjust how much mirror tap cable sticks out so that the connection at the detector does not bend sharpliy at the RJ-11 connection.




Good luck!

 

 

I used a piece of cat 5 cable to test the purple power, I could not get the tap in far enough...

 

 

Yes there are two. One is for Corvettes with the self dimming mirror, the other without a self dimming mirror (it has a lever that you use to manually dim the mirror that is on the back of it.
Here's a link https://store.blendmount.com/corvett...ent-c1925.aspx

 

Actually its very simple, and easy. The big tricks are selecting the right size tap out of the kit, and getting it inserted far enough. A small set of needed nose to push the tap all the way in is a huge help. Less then 30 minutes to tap the mirror for power, and to install and mount the detector on it.

That is key, getting the tap to seat all the way.

I found if if you push the tap in on the cent side of the plug cavity it goes in easier and deeper.

 

 

As indicated in my previous posts my purple wire going to the inside mirror was working, but is now dead. I have found the fuse for the purple switched wire going to the inside rear view mirror.
It is fuse #51 located in the engine compartment fuse block. One side of the fuse was blown.
It's a Micro3 Blade 5 amp fuse. Why was it so hard to find it in the Corvette Owners Manual? It is listed as being for the "Instrument cluster"!





As you can see above this is a 3 blade fuse. The middle blade supplies the 12v power, the outer blades are TWO 12v fused circuits, each fused at 5 amps.
Autozone never had seen such a fuse!

NAPA had seen them, but they are not displayed with there in store fuse display. The parts guy helped me and said he had seen these before but had none
in stock. Upon checking what was available in their warehouse he said they had them. I said ,"OK get me two". He checked again and found out that there was only ONE in inventory. LOL!!
On a side note, this appears to be the same fuse as used by FORD. I should have mine this coming Monday.

So, maybe I can get my radar detector to switch on and off with the ignition as long as the detector doesn't push the load over 5 amps when added to the purple wires circuit intended designed load.

 

^^
Thanks for the feedback! Looks like you found the problem!