Rear Defrost not working after Heated mirror DIY

[flash22]

Your doors are prewired for heated mirrors

[mmisch]

Imagine, I connect everything properly, how do I turn on the heated mirrors when it got power via the heated mirror 10A fuse? Is it all linked with the rear defroster?

[flash22]

Yes

The Defrost Button sends a signal to the A/C amplifier or integration relay that in turn turns on the DEF relay that sends power to the heated window and the 10a fuse for the mirrors, It's hard to detect the heat coming from the mirrors unless you use a thermal camera or lightly mist the with water

[mmisch]

Just now, flash22 said:

Yes

The Defrost Button sends a signal to the A/C amplifier or integration relay that in turn turns on the DEF relay that sends power to the heated window and the 10a fuse for the mirrors, It's hard to detect the heat coming from the mirrors unless you use a thermal camera or lightly mist the with water

Well U can really feel the heated mirrors when turned on, but as soon as I have time I will show the mirror connector.

I just noticed; I do have this picture i've taken before but I think it's not clear enough

[flash22]

From what i can see, you have the wiring up to the connector (Green and a white with black stripe) but not to the mirror (2 black wires)

 

IIRC the mirror heats up to 25ºc

[mmisch]

Here are the pics

[flash22]

As i stated in my previous post, you have the wiring, just not to the mirror

[mmisch]

How am I supposed to put the wires in the connector? I don't  have those terminals to put in the connector.

 

Are these the pins for the mirrors? (I don't  know if i have the + and - correct)

[flash22]

That's correct, usually you just change the mirrors, i take it you have just changed the glass, these connectors are used in loads of Toyota's - go and find one in a scrapyard and salvage the pins and wiring or find a broken mirror from a crashed car

[mmisch]

I bought new mirror glass with the heating element, i already wired them but I only need that kind of female terminal to go in that plug, but I don't  know how what i need to search  to find it

 

Update: like these things (molex crimp connector?) 

[mmisch]

On 7/11/2022 at 7:29 PM, Mooly said:

The easiest way is just to connect the mirrors in parallel with the heated rear window. When that is on the mirrors are on.

This means you connect one terminal of each mirror to ground and the other terminal on each mirror goes to the 12 volt feed to the rear window glass. 

You should fuse the mirrors separately for safety.

 

Even though I do have the wiring from factory for 90%, I think its easier for me to just do it like this, I already have the wiring and still a long cable left over. The female terminal is so hard to get here without  spending to much money

[Derek.w]

20 hours ago, mmisch said:

I already have them trough the rubber door grommets, but i meant from under the pedals trough the side of the car where u step in ur car to the back.  

No i'm  not cutting anything but my I meant; the rear defogger has a 30A fuse, do the heated mirrors take Amps from the 30A fuse or does it run seperatly from the fuse I plan to use between the wiring?

That's  something I still don't quite understand

It looks to me that you coupling into a 30  amp feed at the front of the vehicle so need to fuse mirrors heater at 2 or 3 amps.

If you you connecting to the 30 amp feed from the front of the car thats ok but you still needs to fuse your own wiring as close to your connecting point of the 30 amp fuse but at a lower value of 2 or 3 amps to feed heaters on the wing mirrors.

I prefer seterate fuses to each mirror.

You are not going to pull 30 amps out of the system for the mirrors that the total ampage for all systems linked to this fuse.

But if you dont fuse your own wiring and one of them shorts out to earth then yes it will pull over 30 amps and blow that fuse.

So please protect your own wiring with some lower value fuse even if its 5 amp one.

 

[mmisch]

2 minutes ago, Derek.w said:

It looks to me that you coupling into a 30  amp feed at the front of the vehicle so need to fuse mirrors heater at 2 or 3 amps.

If you you connecting to the 30 amp feed from the front of the car thats ok but you still needs to fuse your own wiring as close to your connecting point of the 30 amp fuse but at a lower value of 2 or 3 amps to feed heaters on the wing mirrors.

I prefer seterate fuses to each mirror.

You are not going to pull 30 amps out of the system for the mirrors that the total ampage for all systems linked to this fuse.

But if you dont fuse your own wiring and one of them shorts out to earth then yes it will pull over 30 amps and blow that fuse.

So please protect your own wiring with some lower value fuse even if its 5 amp one.

 

I did got this today, this is fine right? It came with a 7.5A fuse, is that to high?

[Derek.w]

You be fine with that.

[Derek.w]

Some mirrors are fused at 10 amps

[mmisch]

Wait, u said fuses for both mirrors? Can't I use 1 fuse for both mirrors? But maybe use a higher amp fuse?

[Derek.w]

yes it depends on the system you want to build.

I dont know if this will help but 30 amp wiring  you  want to connect to used to be 

long black short white + feed for rear window & mirrors wiring

long white short black is it appropriate earth connection.

But after saying that I have known manufactures change to avaible colours & use pin location on plugs those never change for a pacticular mfg harness but are a lot harder to  source infomation on.

IE you need to check for yourself that ground is actually ground and is the 30 amp wire using the same colour code that I have suggested.

[mmisch]

I did found out that  the right terminal one is ground because its only a ~10cm wire that comes from the heating element and bolts to the chassis.

The left one goes inside the chassis and is most likely the power wire.. gonna be a PITA because its not behind the panel but inside the chassis itself..

[Derek.w]

Thats why I like to build my own electrical system plus its easer when moving on to return car to maker model specifcations.

But with a heated mirror that possibly wont be possible without just disconnecting the heating element of the mirrors.

I pefere right and left side fuses for all circuits but if it your own wiring any fuse for both zides is ok

Plus usully I refit removed parts ar at least some of them to my next car it saves me time and the car is back to MFG specifcations.

[mmisch]

Yes it's my own wiring, Heated mirrors should've been an standard option imo just like the cruise control that I retrofitted in.

I will take a look at it after I got the new switch, will keep this topic updated untill I got it done or when I come across more problems in the meantime (hopefully not).

Thanks everyone so far for the help.

 

Btw, is 7.5A enough for both mirrors or is 10A better? (Maybe to give some headroom for current spiking or something like that?)

[Mooly]

6 hours ago, mmisch said:

Btw, is 7.5A enough for both mirrors or is 10A better? (Maybe to give some headroom for current spiking or something like that?)

Measure the cold resistance of one of the mirrors (place it in a freezer for a little while first and be quick measuring when you take it out) and then divide 16 (16 volts to allow a margin) by the number you measure. Use a low ohms range on your meter that accurately measures values in the single ohms range.

For example if you measure 6 ohms then the current draw would be 2.6 amps @ 16 volts. Two mirrors would draw 5.2 amps and so a 7.5 or 10 amp fuse would be a suitable value. At 12 volts it will draw less.

Cooling the mirror first is to allow for the heating element being non linear (PTC or positive temperature coefficient) and having resistance that falls as temperature falls. Measuring when really cold gives the worst case current draw. 

 

[Derek.w]

The two wires you are looking for have the same colour coding as your boot/rear door defrost screen.

Just adding from behind the door card its easier to fuse each door modifcation with a seperate fuse.

[mmisch]

3 hours ago, Derek.w said:

The two wires you are looking for have the same colour coding as your boot/rear door defrost screen.

Just adding from behind the door card its easier to fuse each door modifcation with a seperate fuse.

Isn't it easier to just fuse both positive wires at the boot trim near the same place where the 12v is from the heated rear window?

[mmisch]

4 hours ago, Mooly said:

Measure the cold resistance of one of the mirrors (place it in a freezer for a little while first and be quick measuring when you take it out) and then divide 16 (16 volts to allow a margin) by the number you measure. Use a low ohms range on your meter that accurately measures values in the single ohms range.

For example if you measure 6 ohms then the current draw would be 2.6 amps @ 16 volts. Two mirrors would draw 5.2 amps and so a 7.5 or 10 amp fuse would be a suitable value. At 12 volts it will draw less.

Cooling the mirror first is to allow for the heating element being non linear (PTC or positive temperature coefficient) and having resistance that falls as temperature falls. Measuring when really cold gives the worst case current draw. 

 

And I thought just setting my multimeter to Amp and measuring it at the fuse was okay.. (when its powered on)

[flash22]

You do like making things hard for you self, if you don't want to use the connector just splice in to the wiring on the door add the fuse, job done