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Dave12345



Member Since: 04 Jun 2022
Location: North West
Posts: 87

United Kingdom 1989 Defender 90 300 Tdi PU Keswick Green
Side light only on with headlights
As above really - my sidelights work when the headlights are on - but not on the actual sidelights setting. It’s an f-reg 89 vehicle if that’s relevant.

Mot is due this week - any ideas?

I have zero knowledge of electrics by the way.
Post #966949 6th Oct 2022 9:10pm
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blackwolf



Member Since: 03 Nov 2009
Location: South West England
Posts: 17373

United Kingdom 2007 Defender 110 Puma 2.4 DCPU Stornoway Grey
Most likely a defective light switch with those symptoms.
Post #966951 6th Oct 2022 9:23pm
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geobloke



Member Since: 06 Nov 2012
Location: Nottinghamshire
Posts: 4410

United Kingdom 
Hi Dave.

Since it is an F Reg it will have had a Dim Dip relay. Big pink thing behind the dash binnacle. The idea is that with side lights on the main lights illuminate at a very low voltage, a dim light.

It is possible that the light switch has melted, or the relay is duff, or a previous owner has modified the lighting so the side lights are linked to dipped beam directly rather than through the switch.

Hang on you have LED headlights? I forget. Dim Dip does not work with LED headlights. What should happen on a standard vehicle with H4 filament bulbs is that the side lights come on and the H4 bulb at very low illumination. If you have LED headlights fitted then the side lights will come on and the LED headlights as they fully illuminate at much lower voltage.

If that is the case then you need to do a Dim Dip modification to separate the side lights and headlights. It is super easy to do. As it happens Blackwolf and I answered this question yesterday in this thread:

https://www.defender2.net/forum/topic85148.html
Post #966976 7th Oct 2022 8:08am
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blackwolf



Member Since: 03 Nov 2009
Location: South West England
Posts: 17373

United Kingdom 2007 Defender 110 Puma 2.4 DCPU Stornoway Grey
Unusually the OP's symptoms do not sound to me like a dim-dip artefact, unless a previous owner has (bizarrely) chosen to disable the sidelight function completely in order to prevent the LED lights struggling to work on the reduced voltage. This would be an extremely irrational approach but people are strange sometimes!

I do however think this is unlikely since if they had done so then a further modification would be needed to make the sidelights come one with the headlights.

As note above I do think it is more likely that the OFF/S&T/HS&T stalk switch is on the blink, and given that it is relatively easy to get at and test it would certainly be my starting point.

If the OP tests it and finds that it works correctly then posts back, the collective forum brain can have another think.
Post #966983 7th Oct 2022 9:02am
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Dave12345



Member Since: 04 Jun 2022
Location: North West
Posts: 87

United Kingdom 1989 Defender 90 300 Tdi PU Keswick Green
Sorry I should add - normal headlights, and one of the sidelights still works when sidelights only, just not the other.

I assumed it was a bulb but it works with the main headlights
Post #967161 9th Oct 2022 11:59am
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Dave12345



Member Since: 04 Jun 2022
Location: North West
Posts: 87

United Kingdom 1989 Defender 90 300 Tdi PU Keswick Green
It does sound like the switch could have had its day

https://www.lrparts.net/prc3430-defender-m...-1998.html

This would be the correct part for an 89 would it not? For £12.50 it sounds like an easy way to find out
Post #967164 9th Oct 2022 12:35pm
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Dave12345



Member Since: 04 Jun 2022
Location: North West
Posts: 87

United Kingdom 1989 Defender 90 300 Tdi PU Keswick Green
Got further into investigation and noticed the sidelight indicator doesn’t light on the dashboard - is this relevant?
Post #967172 9th Oct 2022 3:19pm
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Dave12345



Member Since: 04 Jun 2022
Location: North West
Posts: 87

United Kingdom 1989 Defender 90 300 Tdi PU Keswick Green
Christ I’m an idiot

Seems the connector housing for the bulb isn’t fixed properly into place so neither was the bulb, and the bulb was just intermittently making a connection - just coincidence that I’d seen it work on mains only (or perhaps the higher voltage here helped)

Either way pushed the connector back to its proper position and it works.

New lighting loom to skip the switch is on the list now regardless and learnt a few things about these along the way - thanks everyone.

Still curious about the sidelight indicator but that could just be a bulb there too
Post #967174 9th Oct 2022 3:31pm
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