Z3 under bonnet ignition switched feed ?

markrnorton · Post by **markrnorton** » Fri 28 Aug, 2009 09:22

Does anybody know when i can find an ignition switched power feed under the bonnet, preferably near side ??

help

i just dont want to go around testing circuits if somebody already knows

i need a switched tap off for the electric fan rather than the permanent live feed i have at present

Mr Silver · Post by **Mr Silver** » Fri 28 Aug, 2009 09:56

The fan control wiring is quite deliberate and will be the same for any vehicle fitted with an electric fan.

If the engine is very hot when you stop and switch off, its temperature can rise dramatically and cause damage to many parts (sensors, seals etc. going out of range, head or block warping due to uneven temps etc, etc.) and all uncontrolled! It is imperative that the fan is allowed to continue to cool the system as it's designed to do.

Maybe the best of intentions but leave well alone!

...and you've got an SC on it!

markrnorton · Post by **markrnorton** » Fri 28 Aug, 2009 11:07

i'm not sure i've been clear.

i know how the fan works as i fitted it in !!
the 1.9 doesnt come with an electric fan as standard, just the viscous one.
I've removed this and now i am looking for an ignition switched feed

so my question still stands

anybody ???

Post by **Robert T** » Fri 28 Aug, 2009 11:43

Some Z3 models did come with an electric fan, so you could go for a similar wiring arrangement to that if you can follow it on the wiring diagram.

Have you got a thermostat on the fan as you have it wired now?

If you do then it should behave as is common with cars with electric fans and run for a bit before cutting off when the engine cools down sufficiently and you can continue to run it from a permanent live.

If you don't then the fan will run all the time and the engine will take a while to get up to temperature, but should remain reasonably cool if the fan is powerful enough, and with a switched live I would hope that it wouldn't leave the engine too hot when you turn the ignition off.

With the viscous coupled fans, they do turn all the time, so you get some airflow that you wouldn't get with an electric fan that is turned off, but they really only start shifting the air when they lock. With a viscous fan, there is no cooling once you turn the engine off, so as long as you can keep the temperatures within these bounds I don't see a problem with whatever arrangement of electric fan you fit.

Cheers R.

markrnorton · Post by **markrnorton** » Fri 28 Aug, 2009 14:22

electric fan is already wired in with a relay, i have fitted a new stat in the top hose.

obviously it runs on if the engine is hot and the ignition off, but the rad is the only element being cooled at that point as there is no water circulation.

it takes a while for the top hose to cool sufficently to switch the fan off, by then the rad is cold !

i think the way out of the heat sink issue is to fit an electric water pump with remote stat

i removed the viscous fan as it robs power from the engine, and i want to maximise power and minimise parasitic losses

Brian H · Post by **Brian H** » Fri 28 Aug, 2009 15:02

Mark,

Recently I fitted Heated seats and had to fit a relay in the fuse box. The relay circled in yellow is not fitted unless you have heated seats, Pin 8 is a switch live from fuse 23 and pin 4 is a Ground. As long as you are switching a relay I see no differance or problem.

Good Luck

markrnorton · Post by **markrnorton** » Fri 28 Aug, 2009 15:04

Nice one Ardchyle,

thanks very much

spurs fan in a coupe · Post by **spurs fan in a coupe** » Sat 20 Jun, 2015 19:32

Massive thread resurrection (at least I've searched!), but does anyone know if all these little orange relays are interchangeable?

I'm looking to identify the heated seats one.

Is it this one?

Thanks

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Z3 under bonnet ignition switched feed ?

Z3 under bonnet ignition switched feed ?

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