custom window heating - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

churchx · 04-15-2018, 11:17 PM

Some time ago i did brake light relocation to top of the window. Really liked result with better view through rear window with "spaceship" gone, it also looks better from outside, but there is slight usability issue. Stock window heating lines goes only below it, so if glass is fogged, which gets often during parking in winter, it takes ages to clean up in area of brake light (probably due led strip producing little heat and brake light being rarely lit and limited air exchange with rest of cabin).

What best & brightest can advise/suggest regarding adding "extra heating lines" in that area? (or anything else that would work to defog rear window there). What are aftermarket options/how should they be electrically connected? (in parallel or in series to existing heater connections?)

Spuds · 04-16-2018, 12:18 AM

Not sure I qualify for the "best and brightest", but I'll give it a go for a DIY solution...

You could just add a long resistor(s) up by the light and power them off the defogging circuit. Probably in parallel with the actual window.

You'd need to find the appropriate cable(s), measure voltage and current, then figure out the overall resistance of the window (V/I=R). If I'm remembering circuits right, you would count the lines across the window and multiply the total window resistance by that amount to get the individual elements resistance. Probably would want to multiply that by 2 or 3 at least since you don't need that much heat and you don't want to affect the functionality of the actual defogger. That number becomes what you want total resistance to be make sure the resistor(s) are rated to handle the input power so you don't set the car on fire. Connect in parallel with the window circuit and you are done, probably. If you blow a fuse you need more resistance.

If you don't mind running more wire, you could probably just run a separate circuit off the fuse box or something.

PS. I'm not responsible if anyone electricutes themselves trying this. I'm just a dude on the internet.

humfrz · 04-16-2018, 12:41 AM

Bubba says this will work ......

humfrz

churchx · 04-16-2018, 12:43 AM

This is what i googled up. Anyone has experience with these by chance?

04-15-2018, 11:17 PM	#1
churchx Senior Member Join Date: Mar 2015 Drives: 2014 GT86 Location: Latvia, Riga Posts: 4,335 Thanks: 698 Thanked 2,086 Times in 1,436 Posts Mentioned: 53 Post(s) Tagged: 1 Thread(s)	custom window heating Some time ago i did brake light relocation to top of the window. Really liked result with better view through rear window with "spaceship" gone, it also looks better from outside, but there is slight usability issue. Stock window heating lines goes only below it, so if glass is fogged, which gets often during parking in winter, it takes ages to clean up in area of brake light (probably due led strip producing little heat and brake light being rarely lit and limited air exchange with rest of cabin). What best & brightest can advise/suggest regarding adding "extra heating lines" in that area? (or anything else that would work to defog rear window there). What are aftermarket options/how should they be electrically connected? (in parallel or in series to existing heater connections?)

04-16-2018, 12:41 AM	#3
humfrz Senior Member Join Date: May 2013 Drives: 2013 FR-S, white, MT Location: Puyallup, WA Posts: 30,432 Thanks: 29,826 Thanked 32,845 Times in 16,844 Posts Mentioned: 715 Post(s) Tagged: 2 Thread(s)	Bubba says this will work ...... humfrz Attached Images

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04-16-2018, 12:18 AM	#2
Spuds The Dictater Join Date: Apr 2017 Drives: '13 Red Scion FRS Location: MD, USA Posts: 9,657 Thanks: 26,704 Thanked 12,715 Times in 6,298 Posts Mentioned: 88 Post(s) Tagged: 0 Thread(s)	Not sure I qualify for the "best and brightest", but I'll give it a go for a DIY solution... You could just add a long resistor(s) up by the light and power them off the defogging circuit. Probably in parallel with the actual window. You'd need to find the appropriate cable(s), measure voltage and current, then figure out the overall resistance of the window (V/I=R). If I'm remembering circuits right, you would count the lines across the window and multiply the total window resistance by that amount to get the individual elements resistance. Probably would want to multiply that by 2 or 3 at least since you don't need that much heat and you don't want to affect the functionality of the actual defogger. That number becomes what you want total resistance to be make sure the resistor(s) are rated to handle the input power so you don't set the car on fire. Connect in parallel with the window circuit and you are done, probably. If you blow a fuse you need more resistance. If you don't mind running more wire, you could probably just run a separate circuit off the fuse box or something. PS. I'm not responsible if anyone electricutes themselves trying this. I'm just a dude on the internet.

04-16-2018, 12:43 AM	#4
churchx Senior Member Join Date: Mar 2015 Drives: 2014 GT86 Location: Latvia, Riga Posts: 4,335 Thanks: 698 Thanked 2,086 Times in 1,436 Posts Mentioned: 53 Post(s) Tagged: 1 Thread(s)	This is what i googled up. Anyone has experience with these by chance?

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