Retro fitting a heated screen to a 300tdi

[HiFonics]

I have done some searches but no joy.

My friend has a 97 300tdi pick up. It has a heated windscreen switch to the right of the steering wheel, which when switched on lights the heated screen symbol on the dash panel. The vehicle obviously doesn't have any heated screens currently and he therefore plans to use this switch to control the front heated windscreen rather than purchase a rather expensive loom.

We guess that the switch and wiring was fitting when the vehicle was built but we don’t know how much of the loom is there, if it includes a timer, if there is already a space in the fuse box the switch runs to and so on.

Is there anyone that has retrofitted a front heated windscreen and use this existing wiring as he wants to or can provide any info on the wiring that we should expect to find?

[Litch]

Don't forget that the front screen draws significantly more current than the rear so even if the wiring is in place, it is unlikely to be suitable for a front screen.

Heated windscreens are great, had one in my 90 for well over 10-years now but wired it from scratch so I know that everything is over-engineered (electrics used to be my job).

Are you going to use a timer relay or do it manually? Personally I have a manual switch (Carling) which operates two relays (one for each circuit) and have found that about 1-minute is more than adequate for a normal misty morning and under 2-minutes for thick frost / ice.

[western]

see this thread http://forums.lr4x4.com/index.php?showtopic=4766&hl=

if you & mate decide to use the GLR10 timer & momentary switch refer to my wiring diagram at the end of page 6, wiring colour code is my choice,

there is a ready made loom for this job on the market, but can't remember who can supply it, I decided to make my own loom 7 fit it how I wanted it.

[HiFonics]

Thanks Ralph,

I think dedicated wiring is probably the way to go, was just wondering whether it was going to be worthwhile locating the factory wiring and using that through relays for the front screen.

[western]

I suspect the 'factory' wiring is inside the main vehicle loom & not a completely seperate loom, my timer & 70amp relays are mounted on the forward face of the fuse box metal panel next to the factory fit relays, wiring then comes up to instrument switch area via the same route as the standard wiring, my switch is to left of steering column & wire go up right screen pillar to the 3 terminals on screen.