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| Evil Elsie Member Since: 25 Feb 2023 Location: Cumbria Posts: 201   
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Hey folks ๐,
It's still a bit chilly but the big yellow thing in the sky is shinning - happy days ๐๐ My interior light has never worked. All three door switches are missing. I'm not bothered about the light illuminating when I open a door but I do want to be able to switch the light on manually. I've got a good earth but only 11.5v on the purple/black permanent live. 12.5v at the battery. The light works perfectly when connected to a 12v battery in my garage so it has to be the fact that I'm losing 1v on the permanent live. Anybody got any ideas where this pesky Volt may be going..?? Cheers, Dave. 2002 Land Rover 110 Td5 Utility 1990 Suzuki GSXR 1100L 1980 Yamaha RD 350LC 1976 Yamaha RD 400C |
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28th Apr 2024 4:11pm |
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| andy63 Member Since: 30 Jun 2023 Location: north east Posts: 512
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I think it's a bit more than just your one volt missing..
You most probably have a high resistance in that circuit somewhere and when you switch it on and try and pass current you have a very low voltage at the bulb holder.. Try a meter on it and see what voltage you have at the holder with the circuit on.. with current flowing๐ If that wasn't the case your bulb would light even with 11v at the holder.. Try that anyway๐ |
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28th Apr 2024 5:25pm |
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| Evil Elsie Member Since: 25 Feb 2023 Location: Cumbria Posts: 201
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Nice one - thanks Andy..๐๐
I put a meter on the plug that supplies the light - 11.5v. I would have thought that it would light the bulb at that but I get nothing. I've tried the original incandescent bulb and an LED one. Both work when connected to a 12v motorbike battery but not when I connect them to the Landy. Landy Earth is good but permanent live at plug for light =11.5v and not a flicker... Will see what I'm getting at the actual bulb holder tomorrow (started on the Bushmills already ๐). Cheers, Dave 2002 Land Rover 110 Td5 Utility 1990 Suzuki GSXR 1100L 1980 Yamaha RD 350LC 1976 Yamaha RD 400C |
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28th Apr 2024 7:54pm |
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| andy63 Member Since: 30 Jun 2023 Location: north east Posts: 512
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Bushmills .. Very nice..
I'm not that far from the distillery atm๐ |
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28th Apr 2024 8:36pm |
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| Sjmmarsh Member Since: 01 Jan 2023 Location: Lincs Posts: 59 
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You need to measure the voltage across the bulb when it is in the holder and turned on - I suspect it will be way less than 1v, which is not enough to light it up. Your issue is probably a poor connection somewhere that is giving a high resistance to the current flowing through the wires. Chase the wiring back to the source and pull and reconnect any plugs. Also check the earth at the lamp - if that has poor contact then you have found the issue. (Check the resistance between the -ve end of the bulb holder and an earth on the dash (e.g. outer rim of the lighter socket). It should be no more than 1 ohm Steve |
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29th Apr 2024 9:11am |
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| PauloA Member Since: 29 Apr 2024 Location: Bristol Posts: 11 
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Can you follow the wire back through the dash to see if there are any issues?
Another alternative is to ditch the old wire and run a new wire from the relevant terminal in the fuse box and up to the roof...or a permanent live (ideally with an inline fuse as a minimum). Cheers, Paul Edited to add: As mentioned above the door switches make the earth path so you might want to run a new, known good earth as well as a 12V supply. |
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29th Apr 2024 6:01pm |
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| custom90 Member Since: 21 Jan 2010 Location: South West, England. Posts: 20314
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Sounds like, as mentioned, possibly high resistance, could be caused by poor contact(s) live or ground sides.
The connector(s) could have poor contact, itโs also grounded by the backing plate, and that has a connector on it also. (Ground). Check the voltage with it turned on, in parallel (across the light bulb or LED fitting contacts). See what that shows voltage wise, you can also see what current draw itโs pulling by checking in series. Bearing in mind, current draw will be significantly lower with LED than the standard fitting. If I remember rightly, current draw shouldnโt be any more than 1.2A max for the standard light not lower than Approx 800mA or 0.8A. LED is much lower, but you can factor in the current draw it should be by testing it from an alternative voltage source. Is the fuse fully in-tact? Iโm not sure however exactly which one it is. The door switches ground the light if a door is open if powered by AS10, but as you rightly say there is the permanent on off option. If you had a door switch and that doesnโt work either, and the same issues with both circuits then a common ground issue is likely if there are two power supplies that appear to be working as they should. With an insufficient ground, that may be the common issue. Beware the A pillar trims also, the wiring goes up behind there, it has been known for these to be removed (the trims.) and the wires trapped by the fixings or a screw driven through the screws present. โญ๏ธโญ๏ธGod Bless the USA ๐ฌ๐ง๐บ๐ธ โญ๏ธโญ๏ธ |
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29th Apr 2024 7:37pm |
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| Evil Elsie Member Since: 25 Feb 2023 Location: Cumbria Posts: 201
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Thank you all for the help and advice - and apologies for taking so long to reply..
Just in case it helps someone else; Voltage checked at bulb holder = 11.49v in all three switch positions and without bulb fitted. Voltage checked at bulb holder = 6.5v in the 'On' position with bulb fitted. (11.49v with tHe switch in the other two positions). So, as suggested, a dodgy connection in the 12v supply. I've ran a new supply to the light (from the leisure battery - just in case I forget and leave it on) and for the first time in my ownership I have an interior light..๐๐๐ Cheers, Dave. 2002 Land Rover 110 Td5 Utility 1990 Suzuki GSXR 1100L 1980 Yamaha RD 350LC 1976 Yamaha RD 400C |
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10th May 2024 8:59am |
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| Screbble Member Since: 26 Apr 2015 Location: Lancashire Posts: 2081 
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Great result ๐
Wonโt be long now until the days get shorter and the nights draw in and you can gain the benefit  |
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11th May 2024 6:35am |
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