Interior light and boot light.

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h11poc
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Interior light and boot light.

Post by h11poc » Sat May 22, 2021 6:56 pm

Good evening all. Just a quick question. My interior light does not work and nor does the boot light. I have done the following checks...

Both bulbs installed and all good
Door jam and boot jam switch undone and checked - all connections clean and connected.
Fuses checked - all Fuses good.

What other reason could there be for these lights not working?? I would assume somewhere these wires are linked and earther somewhere but my haynes manual and a search on here have revealed no information (unless I didnt search correctly)

Has anyone else had both boot light and interior light fail and worked out a solution??

Your help is greatly appreciated.

Paul



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james butler
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Re: Interior light and boot light.

Post by james butler » Sun May 23, 2021 11:06 am

does your cigarette lighter socket work?


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h11poc
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Re: Interior light and boot light.

Post by h11poc » Sun May 23, 2021 1:12 pm

james butler wrote:
Sun May 23, 2021 11:06 am
does your cigarette lighter socket work?
Hi , NO it doesn;t I tested it today . The cigarette lighter bulb worked but the cigarette lighter NOT



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Re: Interior light and boot light.

Post by WreckTangle » Sun May 23, 2021 2:06 pm

Given all the above are you absolutely certain the 15A fuse in position 3 is not blown? It serves cigarette lighter, radio, dash clocks, interior lights, and central locking (if fitted).



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Re: Interior light and boot light.

Post by h11poc » Sun May 23, 2021 2:40 pm

WreckTangle wrote:
Sun May 23, 2021 2:06 pm
Given all the above are you absolutely certain the 15A fuse in position 3 is not blown? It serves cigarette lighter, radio, dash clocks, interior lights, and central locking (if fitted).
Hi , I checked fuse three and replaced with a new one just in case but still no interior lights or cigarette lighter. The radio was aftermarket and that worked but I have taken that out now. I am not sure if I have central locking or not.



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james butler
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Re: Interior light and boot light.

Post by james butler » Sun May 23, 2021 5:17 pm

sounds like either bad earth or the wiring has been messed with/unplugged
like wrecktangle has said this one fuse feeds a lot of things hence why i asked the question.
time to get the multimeter out and test the lives where the bulbs go and the cigarette lighter and see if you have a live feed.


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h11poc
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Re: Interior light and boot light.

Post by h11poc » Sun May 23, 2021 7:03 pm

james butler wrote:
Sun May 23, 2021 5:17 pm
sounds like either bad earth or the wiring has been messed with/unplugged
like wrecktangle has said this one fuse feeds a lot of things hence why i asked the question.
time to get the multimeter out and test the lives where the bulbs go and the cigarette lighter and see if you have a live feed.
HI James. I tested the interior light ang the multimeter showed 12.08 volts when i tested it. And i tested both eart terminals on the interior light. 12 volts !! Interesting.
How can there be 12 volts with a new bulb but it doesn;t light up !! I think I may have a whole host of things to check now.



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Re: Interior light and boot light.

Post by WreckTangle » Sun May 23, 2021 9:04 pm

12V on the earth means it’s not making a circuit with battery negative for some reason. That’s a classic “loaded neutral” symptom. I cannot remember how it works on the scirocco. Normally, car door switches make the circuit to earth via the bodywork. The connection can go bad if the screws rust.



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Re: Interior light and boot light.

Post by h11poc » Sun May 23, 2021 9:31 pm

WreckTangle wrote:
Sun May 23, 2021 9:04 pm
12V on the earth means it’s not making a circuit with battery negative for some reason. That’s a classic “loaded neutral” symptom. I cannot remember how it works on the scirocco. Normally, car door switches make the circuit to earth via the bodywork. The connection can go bad if the screws rust.
I have no clue what to do next...My cigarette lighter doesn't work , the interior lights don't work !! I can try to chase the earths but the haynes manual is about as useful as a chocolate teapot. I have no idea how to read those diagrams.



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Re: Interior light and boot light.

Post by GT_II » Mon May 24, 2021 1:29 am

12V both sides of the lamp tells you that you have power to the lamp, but no earth. This would of course by the case if the light switch was turned to "off". As soon as you get a good earth, either by switching the light to "on" or by switching to "on with door open" and opening a door, the voltage on the earth side of the lamp should drop to near zero. If it doesn't, you have a bad connection to earth.
WreckTangle wrote:
Sun May 23, 2021 9:04 pm
12V on the earth means it’s not making a circuit with battery negative for some reason. That’s a classic “loaded neutral” symptom. I cannot remember how it works on the scirocco. Normally, car door switches make the circuit to earth via the bodywork. The connection can go bad if the screws rust.
What WreckTangle says is correct for the Scirocco. The contacts in the door switches may be corroded or lacking their spring, or the screws that secure the switches to the door frame may be corroded.

I sympathise with the comparison you make between the Haynes Manual and a chocolate teapot, as the wiring diagrams take some getting used to. The following little "tutorial" may help you to get your head round how the wiring diagram works for the interior light and hopefully then help you to use the diagram to investigate the other electrical issues:

If you look at the wiring diagram for post-1985 cars in Figure 11.38 in the Haynes manual using the key on Page 287 (assuming you have the red 1991 edition), you can see the wiring layout for all components on the car.

For example, if you search for Interior light in the key on Page 287, it tells you it is labelled "W" on the wiring diagram, and that you can find it in Tracks 56 and 57 of the diagram. The track numbers are labelled at the bottom of the diagram, so turn the page to locate Tracks 56 and 57 and you will find "W" about half way up the page. The track above "W" shows that the interior light is fed by a red wire labelled "ro" ("rot", for red in German), which comes from Terminal E3 on the fuse/relay board via Connector T1h, located somewhere behind the dash.

Three other wires flow out from interior light. The one in Track 56 is coloured brown ("br") and connects to Earthing point 10 (represented by a 10 in a circle, which according to the key is near the relay plate). This would be the wire for the "Permanent on" switch position. The wire in Track 57 coloured brown/white ("br/ws" for "braun/weiss" in German) connects to F2 (from the key, left door contact switch). This doesn't have an earthing wire but connects directly to earth via the switch body, as represented by the thin line). The wire in Track 58 coloured black ("sw" or "schwarz" in German) connects to F3 (right door contact switch), and also connects straight to earth via the switch body.

The key to the German colour codes in Diagram 11.38 is in the second column on Page 269.

The solution to other electrical issues might also boil down to rectifying bad earths. Hopefully the wiring diagrams may help you to locate and check the circuit layout and earthing points, but if not, especially if it appears your electrical system may have been tinkered with in the past, you might save a lot of headache by finding a good auto electrician.
Last edited by GT_II on Mon May 24, 2021 10:09 am, edited 1 time in total.


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h11poc
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Re: Interior light and boot light.

Post by h11poc » Mon May 24, 2021 7:38 am

GT_II thank you for that. That has really helped me a lot. My version is the 1990 Red haynes so slightly different layout but yes, it is all there.



h11poc
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Re: Interior light and boot light.

Post by h11poc » Mon May 24, 2021 3:03 pm

SOlved !! The boot light had a dirty switch where corrosion had occurred where the door jam part touches the switch - All cleaned and now the boot light comes on

Interior switch was again ever so slightly bent where the switch touches so barely made contact in either position. I got it to work but then it snapped in half !!. Ordered a spare on the bay and it will be here soon but at least i know everything works now.

So the indicators now sorted and hazards as it was missing the relay . all interior lights work. Just the horn to go before I tackle the Pierburg rebuild.



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Re: Interior light and boot light.

Post by mark1gls » Mon May 24, 2021 8:00 pm

Good to hear you are working your way through all the electrical problems. :-D


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h11poc
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Re: Interior light and boot light.

Post by h11poc » Tue May 25, 2021 1:16 pm

Well the horn was pretty simple. I looked under the battery tray and both terminals had been disconnected from the horns. Plugged them back in and turned on the ignition and they work.

Im sort of guessing maybe the GTii didnt come with central locking which is a pity.



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Re: Interior light and boot light.

Post by mark1gls » Tue May 25, 2021 10:32 pm

Better off without central locking, 1 less thing to go wrong. ;-D


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