Light switch - panel illumination

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dazthephot
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Light switch - panel illumination

Post by dazthephot » Thu 25 May, 2017 21:58

I've just replaced the 1.2w bulb in the small panel under the light pull switch.
Is it supposed to be on all the time when the key is turned to pos II? Instead of just when you pull the the light switch on.
This has bugged me for the 10 years of ownership and it's the first time I've made the effort to change it.


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Robert T
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Re: Light switch - panel illumination

Post by Robert T » Thu 25 May, 2017 22:56

Yes. It is there to help you find the headlight switch. This is why they are frequently burnt out.

Cheers R.

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dazthephot
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Re: Light switch - panel illumination

Post by dazthephot » Fri 26 May, 2017 08:38

Ha ha I see just as well I bought a couple from eurocarparts. Cheers.


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Fender2004
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Re: Light switch - panel illumination

Post by Fender2004 » Fri 26 May, 2017 09:51

This puzzled me when I first got my Z3, I assumed it was a dealer part :head:

Now I know I'll try europarts first :D
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dazthephot
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Re: Light switch - panel illumination

Post by dazthephot » Fri 26 May, 2017 17:03

Yep normal 12v 1.2w bulbs for about £.40 each. I ordered a couple and they came in a massive box!

Link: http://www.eurocarparts.com/ecp/p/car-p ... 6&&cc5_401

They'd be better wired to the heater panel illumination i think, i might do that if they don't last long.

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Brian H
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Re: Light switch - panel illumination

Post by Brian H » Sun 28 May, 2017 09:41

dazthephot wrote:Yep normal 12v 1.2w bulbs for about £.40 each. I ordered a couple and they came in a massive box!

Link: http://www.eurocarparts.com/ecp/p/car-p ... 6&&cc5_401

They'd be better wired to the heater panel illumination i think, i might do that if they don't last long.
Good idea however be careful when you are doing this, there is no fuse in this circuit, one mistake and you will blow the dimming function in the headlight switch.

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dazthephot
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Re: Light switch - panel illumination

Post by dazthephot » Sun 28 May, 2017 22:43

Ah right, ok. So the heater panel illumination isn't fed from the light pull switch then? I thought I could just T off from the heater panel lamp straight to the light pull switch illumination and all would be well! No?


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Brian H
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Re: Light switch - panel illumination

Post by Brian H » Mon 29 May, 2017 19:11

dazthephot wrote:Ah right, ok. So the heater panel illumination isn't fed from the light pull switch then? I thought I could just T off from the heater panel lamp straight to the light pull switch illumination and all would be well! No?


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Yes the heater panel is off the pull light switch, you can adjust the brightness of the panel illumination by twisting the switch, I was just making you aware that there is no fuse in that circuit, if you short it out by mistake it blows the rheostat in the pull light switch and therefore non of the lights will work.

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dazthephot
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Re: Light switch - panel illumination

Post by dazthephot » Mon 29 May, 2017 22:56

Ah right thanks. I could put a 5 amp fuse inline to help prevent that or does the 1.2w bulb act as a fuse?


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Robert T
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Re: Light switch - panel illumination

Post by Robert T » Wed 31 May, 2017 10:08

That's not quite true. Assuming that I am reading the wiring diagram correctly, the supply to the rheostat is protected by a 10A fuse (F37), which also supplies a few other things as well.

The problem I think is that the rheostat itself is not rated at 10A, so in the event of a short circuit in one of the backlighting bulbs that it controls, it burns out before F37 blows. It could really do with a second fuse after the rheostat with a much lower rating - with a 1.2W bulb drawing 0.1A, then even 5A might be too high, as I don't know what the rheostat is rated at - there certainly aren't 50 bulbs connected to it, but there are more than you might think.

For the knob illumination, I would be tempted to put a 1A inline fuse on it (cable tie this safely out of harms way) and extend the wires to the knob. Then if one of your knob wires does get trapped, it blows the fuse first and protects the rheostat. All the other wiring should not be at risk of getting trapped and shorting out.

Note that the backlight for the headlight pull is on a separate circuit which is "hot in run and start" protected by a 5A fuse (F23).

Links to wiring diagrams are in the knowledgebase.

Cheers R.
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dazthephot
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Re: Light switch - panel illumination

Post by dazthephot » Wed 31 May, 2017 14:03

Very good answer thank you.


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