[V8] Timed rear demister vs non-timed

[CavalloGT]

Dag,

I can't tell you for sure either way, but if you compare wiring schematics and the relay pins match up, and you can confirm that the timer circuit is built into the V8 relay, then it should work.

The reasoning behind the auto off 10 minute timer is to prevent excessive current draw from large consumers in stop and go traffic situations where there is hardly sufficient alternator output to keep up with demand. Instead of redesigning alternators this was the easy way out.
In fact, in the 80s I remember this circuit being implemented at Honda because we were having vehicles die in NYC traffic as the battery was drained because more was being sucked out than was being replaced under those conditions. The fix was the rear defroster timer, and for "special cases" a smaller diameter alternator pulley to spin that bad boy just a bit faster at idle.

Thanks,

ProfessorGT
(Sent from my iPhone4)

> On Dec 22, 2014, at 7:38 PM, Dag Bøsterud <dag.boesterud at little-e.com> wrote:
> 
> On the 1992 Audi V8 I owned a few years back the rear demister (heated rear
> windscreen) was timed - it turned itself off after 10-15 minutes.
> 
> At the moment I own a 1990 Audi 100 TQ Sport Exklusiv, and that car doesn't
> have this feature.
> 
> 
> 
> When I look in ETKA, I see that there are several different switches for the
> rear demister.
> 
> 
> 
> Can I just replace my non-timed demister switch for a timed one, or will
> something fry? :p
> 
> 
> 
> /Dag
> 
> 1990 Audi 100 TQ Sport Exklusiv
> 
> 
> 
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