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Heated Windscreen

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Hello All,

I had a rambling paragraph written, but it was hard to follow so;

I've put in a heated front windscreen on the car, I can't work out how to wire the thing up.

So each corner of the the 'screen has two cables jutting out, reinforced/ strong but flexible with metal tips on the end (so 4 total)

Not sure if anyone has seen such things before (ill take a pic to help later tonight) or how to wire them up, idea is to another rear window switch to control it ?

As an aside to this, I'm thinking about the alternator and battery,.

I'm at the point of buying new ones for the car, so worth upgrading (bigger capacity for both?)

Cheers,
Adam.

'83 MK1 Golf GTI
'02 Land Rover Discovery 2 Td5
'08 Audi S3 2.0 16v TFSI

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When wiring a accessory device that will use a large amount of amperage, that is more than 5 amps, it is best to use a relay that is able to handle the current.

The Windscreen Heater is similar to the rear demister(defroster).  

One side will be tied to the source power (B+  12VDC positive) the other directly to ground.

Gimmies.  
If you haven't replaced your ground (earthing) cables from Battery to Frame and Frame to engine/tranny now is the time to plan on that.

You will want to make a new ground point for either side of your windscreen, that is you have to take one side to ground, and a local to the item ground is going to serve you better than trying to run it back towards the battery, as that extended run will increase the resistance of the circuit.

For the Power side you will want to use a Relay.  The Standard Fog light relay rated up to 40amps should suffice.  

A relay is a Mechanical or Solid state device that uses small current to switch on large current devices with minimal lose to the circuit.

Your relay will be tied directly to the battery using a 20-30 amp in-line fuse or circuit breaker.  
You will also need to make sure that your wires are rated for more than the current they will be carrying.

That is don't use a 22ga wire to run 40 amps, the wire while thrilled that it is being over used will quickly release its bowels itself and allow all the inbuilt smoke to be released.

I would say 12 to 14 Gauge wire would do nicely, same for the ground point.

You will wire the pick side of the relay to a switch that either makes or breaks ground or power, Your choice, but you would also want to use a fuse on that side of the circuit and a signal lamp as well. (5Amp).

Defroster switches work good as you could light it up with the dash or console lights and then have the on/off lamp as well.

The manufacturer probably included a installation guide for the unit.  You can probably also look on line for one as well.

My two pence of thoughts.





What do Divorces, Great Coffee, and Car Electrics all have in common?

They all start with GOOD Grounds.

Where are my DIY Links?

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Thanks for the detailed reply Brian.

They did and do offer some instructions, but nothing specific and rather more simplistic than your post.

I think I might have to have it taken care of professionally…. idea of a smoke and fire machine isn't entertaining  

Cheers

Sent from my EVA-L09 using Tapatalk


'83 MK1 Golf GTI
'02 Land Rover Discovery 2 Td5
'08 Audi S3 2.0 16v TFSI

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I forgot to add diagram for you, but whether your windscreen uses Liquid or Wire as your conductor you sill will use the basic drawing.  


What do Divorces, Great Coffee, and Car Electrics all have in common?

They all start with GOOD Grounds.

Where are my DIY Links?

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just to add the reason you have 4 wires on the screen is there are 2 'sides' to the heating circuit so like the above pic but double it.

what you need to find out as well is what ampage draw each circuits will use, or the whole screen in total. that dictates the size of the fuse and relay needed to run it all. i,.e. if more than 20amp per side you will need 2x relays and fuses, since the switched relays you find generally rated for 40a

Ford often have these as standard and tend to have a timer so if you forget to turn the screen off once cleared the relay switches off for you, might be worth looking into.

extra infos here, the diagram is much the same as brianos just includes the terminal numbers on the relays which will be handy for you:
http://www.heatedwindscreen.com/acatalog/wireing_details.html

for the ignition side of the switch if you use the G spades 1, 2, 3 or 5 these are already fused for you so that saves adding an extra fuse just for the screen switch :)

Hello my name is John and I'm a dub addict.



My wiring diagrams and other documents have moved here:

VAG Documents & Downloads

You'll need to sign into google/gmail for the link to work! (its free!)

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this could be relevant to your interests, technically its VW ;)
http://www.ebay.co.uk/itm/391622837152

Hello my name is John and I'm a dub addict.



My wiring diagrams and other documents have moved here:

VAG Documents & Downloads

You'll need to sign into google/gmail for the link to work! (its free!)

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Just dug out a wiring diagram for the Sharan, its nothing special the relay is a normal switched one and its triggered by the rear screen heater switch so they're both on together.

The relay you need if you do go for the sharan/galaxy loom off ebay is a 100 70a relay part number 7M0951253A, used for all kinds of things across the VAG range. Most common if scrappy hunting would be mk4 golf, its used for the X relay as well as SAI pump on later petrol models. Its replaced by 4H0951253 which is a 644 if you happen to find one of those. its 14.94+VAT from the dealer if you wanted it new

Hello my name is John and I'm a dub addict.



My wiring diagrams and other documents have moved here:

VAG Documents & Downloads

You'll need to sign into google/gmail for the link to work! (its free!)

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Yikes, thats a lot of info guys.. thanks for taking the time.

Will try digest it all :)

Sent from my EVA-L09 using Tapatalk


'83 MK1 Golf GTI
'02 Land Rover Discovery 2 Td5
'08 Audi S3 2.0 16v TFSI
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