I am after some technical help please.

My passenger side front side light has stopped working. I have taken the headlight out, new bulb in and still nothing. Swapped the working bulb from the drivers side, just to check, still nothing.

Investigated it further today with a multimeter.

Circuits have continuity, so it looks like the wiring is okay. Tested the bulb as well, that was okay.

Voltage on the passenger side lamp connector with the headlights on was 10.89 volts. Drivers side was 11.4 volts (engine not running at the time).

I am now stuck! The circuit appears okay, voltage is getting to the lamp (albeit on the low side i think), it just won't light up.

Would it be worth disconnecting the battery and touching the leads together? I read on here that resets the car, perhaps the canbus is confused??

Any suggestions, does this ring any bells?

Thanks in advance... 2013 SD4 Auto HSE Luxury Firenze Red
2003 Defender 90 TD5 XS - gone.
2010 SD4 XS Auto - gone.

If you are getting a feed to the lamp and it's not working and the bulb is okay, that can only leave the earth circuit. Bad connection at bulb holder maybe? I had to fit another holder to mine once - I robbed it out of a spare headlamp I had. Past: FL2 TD4 HSE Auto
Evoque SD4 Dynamic Lux Auto
Present: Audi A3 S Line.

Thanks for that. Do you know how I can check the earthing circuit?

I attached the multimeter to the positive and negative feeds in the lampholder and it beeped on the continuity setting. I think that means the circuit is okay? Would an earthing problem not show up when I did that?

Sorry if these are lame questions, I am still learning about this stuff! 2013 SD4 Auto HSE Luxury Firenze Red
2003 Defender 90 TD5 XS - gone.
2010 SD4 XS Auto - gone.

First of all never 'bell out' a circuit, invariably it will beep as there will be many paths the signal can return through, secondly if there is any voltage it will blow the meter or the circuit, bell out cables to test continuity by all means.

Lamp holders are fairly poor quality, so yes start with that, after checking fuses etc.

Thanks Taz, I have watched a few more you tube videos now, so have a clearer idea of what to do

I suspect the bulb holder, but am puzzled by it showing a voltage across it when I test the terminals in the holder. I would have thought if the holder had failed, then there would be no volts shown - instead I am getting 10.5 volts or so. I will try it again putting the negative terminal on the battery instead.

Beyond that I may have to revert to my mechanic! 2013 SD4 Auto HSE Luxury Firenze Red
2003 Defender 90 TD5 XS - gone.
2010 SD4 XS Auto - gone.

The presence of a voltage can be misleading, 10.5v suggests a bad connection, it should be 12v.
Test the voltage from each pin back to the battery, one should read 0v And the other 12v and vice versa, any other reading and it's a bad connection somewhere.

thanks for your help. 2013 SD4 Auto HSE Luxury Firenze Red
2003 Defender 90 TD5 XS - gone.
2010 SD4 XS Auto - gone.

hi there, when you say you have tested for continuity which wires have you tested,

i ask because i had a really odd problem with my freelander, the high level brake light stopped working, at first i thought it was the bulb, i did a visual check and the bulb looked fine, so then i wondered if it was the towbar wiring as this was fitted a couple of months ago.

but before ripping all of the panels out to get to the wiring i did a diagnostics check with my jlr sdd and it came up with cant communicate with control module.

this is when i started to think what now, anyhow i did a continuity check on the bulb positive and negative terminals and it showed that there was continuity across the terminals, basically the bulb had shorted out somewhere but the filament looks 100% ok.

in 30 years of car ownership and 40 years of bilk ownership and doing everything from replacing clutches and dmf and rebuilding bikes i have never known a bulb to short out in this way.
anyhow i replaced the bulb and the sdd doesnt shown any dtc relating to the high level stop lamp

i still have a problem with the dpf but thats another other story

Quote:

Free-lander said
basically the bulb had shorted out somewhere but the filament looks 100% ok.

Eh

A lamp will always show as a 'short' unless you have a very low range on your meter to measure its resistance.
The brake lights are fed via FET devices, these are basically an 'auto resetting' fuse, they can be misleading in themselves.

hi taz, the meter didnt give the same reading as the new bulb

when i refit the original bulb it doesnt work even when connected to a battery it doesnt work,

i am just glad that its not something more serious

More testing done, rigged up a bulb with two wires and tried it directly in the headlamp connector, still not working, so thinking it may be a short in the feed to the headlamp or an earthing problem as Steve suggested.

Will keep trying!

Frustrating, as with most things on my car...  2013 SD4 Auto HSE Luxury Firenze Red
2003 Defender 90 TD5 XS - gone.
2010 SD4 XS Auto - gone.

taztastic wrote:

First of all never 'bell out' a circuit, invariably it will beep as there will be many paths the signal can return through, secondly if there is any voltage it will blow the meter or the circuit, bell out cables to test continuity by all means.

Lamp holders are fairly poor quality, so yes start with that, after checking fuses etc.

I had a similar problem of a front side-light not working when I swapped the bulbs for LED ones, I left the lights turned on while changing them to check the polarity and one of them wouldn't work either way.

It turns out that the lamps are driven from FET's in the junction box, as Taz says, these serve as fuses in the event of overload, short circuit etc, and can only be reset by removing the main power feed to that circuit, there is a dedicated fuse you could remove, can't remember which one though or you can just disconnect the battery for a short time, this should reset it and solve your problem.

Edited to add, the fuse to remove is fuse 17 in the battery junction box.
This applies to MY09 build, I'm not sure if it applies to all.

Thanks Clive,

I will give that a go tomorrow in he daylight (such that it is with this fog!)

I did have led's in the sidelights, and the nearside one had failed - the bulb that is now no longer working. I wonder if it blew and did something to the control unit.

I will try the fuse reset to see if that works, now reverted back to filament bulbs until I get this working again. 2013 SD4 Auto HSE Luxury Firenze Red
2003 Defender 90 TD5 XS - gone.
2010 SD4 XS Auto - gone.

Bear in mind the LED bulbs are generally polarity conscious, they will only work one way round, I also found that some LED's are prone to flickering due to the CANBUS activity on the lighting circuit, I managed to get some CAN compatible ones which work well but I tried a few first.