Where's the best place to find power for a center brake lamp?

[dodj]

The other brake light is on a different wire.

I didn't know that. So in my mind it would be easiest to tap into the wires at the rear wheel well and using a diode in each wire. That would prevent backfeed onto the opposite brake light so the signal would still work. Is this more or less what you meant by a 'logic module'?
For the time it takes to add two diodes, I would prefer that to removing the sill plate, kick panel, rear seat, and rear interior panel to run a wire.

[Cudaragtop]

...it would be easiest to tap into the wires at the rear wheel well and using a diode in each wire. 

Would run a new wire from the brake switch if the car is apart, diodes if tapping into a driver.
If LED strip, would be cool to split into 2 circuits and have them sequential from center out. 

[Aracer]

Not a specific recommendation for vendor, but if you do not want to run another wire from the dash area to the back, a current example of the logic module I mentioned is available on ebay, possibly also at RV/trailer shops, maybe even better auto parts stores.
http://www.ebay.com/itm/Truck-cap-Third-brake-light-Logic-box-AT-LC-4-Wire-light-to-vehicle-/221868382912
 This is the kind of part for made for new cars that have a different complex electrical system. It's more trouble to work with this gadget by clamping tap the tail light wires, and hide it. An old 62-74 Mopar, is simple and easy to tap the brake light and run a thin wire under the door trim with out dismantling.
OR,,,,,Buy this toy for $3.18 and stick it on the inside window with 3-M molding, stone guard, adhesive tape and run a wire from the white brake switch. (20 minutes of tinkering)
 
http://www.ebay.com/itm/1x-Car-Auto-Red-32LED-12V-High-Mount-Third-3RD-Brake-Stop-Tail-Light-Lamp-Chic-/302083619831?hash=item4655963bf7:g:0VIAAOSwCGVX5Hez&vxp=mtr

[HP2]

I'll admit electronics are a bit of voodoo to me, but I'm not sure a couple of diodes preventing backtalk on the wire accomplishes the necessary task because I don't know how the diodes would differentiate between a brake signal input vs a turn signal input unless you link them to an additional condition to trigger the third brake light. All I think the diode would do is prevent the third light from turning into a turn signal.

[Chryco Psycho]

A diode will not corret the problem from just one wire
 there are separate wires from the turn signal switch to the brake / turn light , the power is interupted through the flasher to the turn light that is flashing so a 3rd brake light will still go off with the turn signal if fed from either of the wires to the rear of the car
You could  tie into both rear wires & use a diode between the connection to each wire & the 3rd brake light this will provide power into the 3rd light but not out to the other light

[1 Wild R/T]

There pages.....

[roadman5312]

There pages.....

                  Three        

[1 Wild R/T]

                  Three        

Gotta love auto correct... Yup, three.... Just adding to the useless dribble... 

[dodj]

You could  tie into both rear wires & use a diode between the connection to each wire & the 3rd brake light this will provide power into the 3rd light but not out to the other light

That's what I said.
The two diodes is probably what aftermarket vendors call a 'logic module' I guess.

[1 Wild R/T]

That's what I said.
The two diodes is probably what aftermarket vendors call a 'logic module' I guess.

By using two diodes with no logic the canter light flashes with either turn signal.... As was stated on page one, connect to the white wire at the brake light switch......

[roadman5312]

                     4 pages soon.              

[duodec]

http://www.ebay.com/itm/Truck-cap-Third-brake-light-Logic-box-AT-LC-4-Wire-light-to-vehicle-/221868382912

 This is the kind of part for made for new cars that have a different complex electrical system. It's more trouble to work with this gadget by clamping tap the tail light wires, and hide it. An old 62-74 Mopar, is simple and easy to tap the brake light and run a thin wire under the door trim with out dismantling.
OR,,,,,Buy this toy for $3.18 and stick it on the inside window with 3-M molding, stone guard, adhesive tape and run a wire from the white brake switch. (20 minutes of tinkering)
 
http://www.ebay.com/itm/1x-Car-Auto-Red-32LED-12V-High-Mount-Third-3RD-Brake-Stop-Tail-Light-Lamp-Chic-/302083619831?hash=item4655963bf7:g:0VIAAOSwCGVX5Hez&vxp=mtr

I have to admit I'm surprised at the resistance to buying a purpose-built part to perform a new function on our Mopars.  Sure you could run that extra wire and tuck it in fairly neatly without too much effort, but even if I did the brake switch tap-off I'd rather do it carefully, and tape or strap that wire to the rest of the harness running to the rear.  And thats more work if you car is already done up (mine is not).  If it were I'd rather just work in the trunk with proper soldered-in taps to the left and right brake lights despite that being modifications to the stock harness. 

Would the new high brake light flash with the hazards if the brake-switch tap is used?  With the logic module it should, if that is desired.

The unit on Amazon and the one I linked on Ebay are functionally equivalent to the modules (often built in) that were included in the retrofit high mounted stop light kits back in the '80s.  They handle the fact that American cars with red rear turn signals use the same wire and filament for stop and turn; that is all.  The Ebay unit is for adding a third brake light to an RV, camper, shell, etc, on a vehicle that does not have discrete turn and stop signaling.

The light you linked to on eBay doesn't appear to seal to the rear window.  You'd get light leakage and reflection into the interior of the car, which would be distracting at night.  The 'original' retrofit lights came with hoods or shrouds that pressed against the rear glass and blocked light leakage into the interior.  I've seen that type still available various places, or I suppose one could be fabricated but then the $3.18 light starts costing more in time and crafting.  There's also no mention that it actually meets any of the standards required here in the US.  On a brief search I didn't find the exact specs but DOT and the NHTSA have standards (and possibly testing certifications) that are supposed to be met for lighting on-road vehicles, almost certainly including the third brake light.  Having an obviously out of spec third brake light on an older car might give an LEO an excuse to pull you over, or give them an addenda to a ticket if you're pulled over for other.  And it could be unsafe if it is too bright and/or produces glare for following drivers.

I don't see a pedestal mount on eBay right now that would allow mounting to the rear package shelf instead of using tape (yuck), but something like this (if the angle is close enough) is the concept I'm thinking of.  Blocks any light from coming back into the car.

[70chall440]

I purchased a light like the one on Ebay you posted for my Challenger; unfortunately the angle was not even close so I could not use it. I like the idea of a 3rd brake light and after some searching could only discover that the light cannot be flashing; must be solid. I am still planning on putting on in my 73 Cuda, but I will build that light once I get the back window back in.

[HP2]

I have to admit I'm surprised at the resistance to buying a purpose-built part to perform a new function on our Mopars.  Sure you could run that extra wire and tuck it in fairly neatly without too much effort, but even if I did the brake switch tap-off I'd rather do it carefully, and tape or strap that wire to the rest of the harness running to the rear.  And thats more work if you car is already done up (mine is not).  If it were I'd rather just work in the trunk with proper soldered-in taps to the left and right brake lights despite that being modifications to the stock harness. 

Would the new high brake light flash with the hazards if the brake-switch tap is used?  With the logic module it should, if that is desired.

The unit on Amazon and the one I linked on Ebay are functionally equivalent to the modules (often built in) that were included in the retrofit high mounted stop light kits back in the '80s.  They handle the fact that American cars with red rear turn signals use the same wire and filament for stop and turn; that is all.

I hear ya.

I guess I'm surprised  that quite a few of us on here are willing to tear into an engine, replace an exhaust system, or spend a day tuning a carb for a few more horsepower but then I see resistance about removing some interior panels to run a single wire for a modified brake light.  Yes, it is much easier to work in the trunk. I see it as either buy a part to allow you to work what you want in the trunk, or run a wire to make the part function correctly. 

If you run the power feed off the brake light switch, no, it will not blink with the flashers or turn signals. That is the point of running it from the brake light switch, only the brakes energize the third light, nothing else. Attaching it to a feed in the trunk without a logic module or using a third brake light without one built in, will result of potential blinking with either turn signal or  e-flashers.

[1 Wild R/T]

I hear ya.

I guess I'm surprised  that quite a few of us on here are willing to tear into an engine, replace an exhaust system, or spend a day tuning a carb for a few more horsepower but then I see resistance about removing some interior panels to run a single wire for a modified brake light.  Yes, it is much easier to work in the trunk. I see it as either buy a part to allow you to work what you want in the trunk, or run a wire to make the part function correctly. 

If you run the power feed off the brake light switch, no, it will not blink with the flashers or turn signals. That is the point of running it from the brake light switch, only the brakes energize the third light, nothing else. Attaching it to a feed in the trunk without a logic module or using a third brake light without one built in, will result of potential blinking with either turn signal or  e-flashers.

Now add to this the poor quality of electronic components coming from China & some folks resistance to a cheap logic module seems more "logical"....