Intermittent light problem, impossible to figure out!?

Hi All,

I have been looking into this on the forum and just cant put my finger on it. Im hoping if I describe the problem below, one of you will just say, ‘Ah, just change the doodaa…’
Hoping….

So, I have a 300tdi defender, love it, but recently on the way home the head lights have just been going off… a bit scary as I live up a mountain in France! Then the next morning, I start her up, check the lights and they work again.
So, when they go off by themselves on a hairpin bend…. switching to full beam doesn’t fix it or work, nor flashing… there is a buzzing coming from the fuse box, one of the yellow switches is vibrating…. Also, the horn stops working, the windscreen wipers go very slowly and on inspection, the side lights and sometimes the indicators are glowing dimly outside the vehicle. The main beam blue light on the dash glows constantly too. . . All very strange. Switching the lights on and off, even trying the cigarette lighter has no effect (but it works…), just increases and decreases the sound of buzzing from the switch in the fuse box by the gear stick.

Ive tried taking all the fuses out and inspecting them… all fine… then sometimes, they just come back on!
I have now stopped driving at night but this is really inconvenient as I have to leave work early! Ridiculous I know, but if ANYone out there can say what is up, please do let me know!

Thanks All!

Mark

Mark,

Sounds like you're having a bit of a 'mare! I've had similar problems myself. There are a number of things that could present these symptoms, poor connection somewhere, bad switch or column 'stalk', or a bad earth. But as a starting point it very much sounds like you have a loose connection somewhere. When diagnosing electrical faults it's unfortunately more a process of working out what the problem isn't, until you find out what it is. I know this probably isn't what you want to hear.

So a couple of questions to start with, what year is your truck? Have you recently done any form of "tinkering" with the electrical system anywhere? Has it been raining heavily or excessively damp? Do you have an electrical test meter/multimeter? Do you have access to a wiring diagram? they're online, and in the Haynes book of lies.

Some things to check in the mean time, you'll need to do this with the ignition on, or at the very least with your symptoms present: remove the plastic cover in front of the gear lever to access the fuse box. Those yellow switches are relays by the way, there should be three of them, i don't have the diagram in front of me right now, but if memory serves, the left one, closest to the passenger side controls your dipped beam. Is this the one that's vibrating? This is known as relay 'chatter' it occurs when the coil inside is rapidly energised and de-energised, sometimes caused by a short circuit - more on that later.

I'd start by prodding each fuse in turn until you get a consistent change in symptoms i.e they stop or start every time you touch that particular fuse. If that doesn't work, try the following; remove the vibrating relay and replace it with any one of the other yellow ones, does this solve the problem? If not; pop your bonnet and access your main fuse-box on the passenger side of the engine bay. Give all the fuses in there a good wiggle, check to see how easily they pull out, if they're tight, that's good. Wiggle the cables coming out of the bottom too. Does any of this change your symptoms?

If none of those things have worked then you're into the realms of disassembling some bits of your dash. The dip/high beam/indicator stalks are notorious for giving you problems. They're about £12/15 from ebay, in short, they end up burning out and giving you bad connections due to carrying too much current and then over-heating. You'll need to remove your steering wheel (which is pretty easy, just make sure you mark the shaft first! you'll need a 24mm standard socket to take the nut off) Then the column cover has about 3 screws in it, that should give you enough access to change the stalk.

The next option is slightly more in depth, you'll need lots of time, a good torch and plenty of patience. Remove the two screws that secure the metal band in which sits your fuse box. The whole assembly should now be dangling in the air allowing you to twirl it about and have a good poke about in there. Essentially what you're looking for is anything metallic that's loose, a stray strand of cable, an old paperclip that's fallen down the back etc etc. At the same time, isolate and give a good eyeball to each and every cable that comes out of the fuse box, you're looking for bare conductors inside, where the insulation may have worn through or melted. Give each cable a good wiggle too, does this change your symptoms? Do the same for the back of the vibrating relay.

I had very similar problems with my 110, in the end the problem was diagnosed to loose spade connections which you fuses slotted into. I just removed each cable in turn and squashed the spade a bit to give a tighter connection on the fuse.

Hope this helps in some way. I'm certain that somebody will be along with some more suggestions soon

Wow Jamo,
Great response, this gives me plenty to get on with.
it is a 1996 300tdi in a brown shade of white.....
i havent done any electrical tinkering in the last few years, i installed an amp (yes i know, but now i have a nice sound..) but that was all wired individually aside form the fuse box.

i have done the switch....switch and found it was the central one vibrating, swapping them achieved little sadly.
i think im going to check the back of the fuses next and if that doesnt work then just get a new switch and install it.. do you think i should also replace the light switch (smaller one below?)

either way, i will post with an update once ive looked at it over the weekend. thanks so much for the advice, shame it wasnt a 'just replace the thingy....' but i believe that would have been too easy!

Mark

Mark,

I wouldn't order a new side light stalk switch just yet, if you've ruled out everything else, and you get to the point that you're replacing the old indicator/flash switch then you'll have an opportunity to eyeball the internals of the side light stalk as it isn't a sealed unit. It's physically bolted to the chassis of the indicator/flash stalk. To seperate the two you'll need long nose pliers, or v skinny fingers. I opted for the first one as there was no chance of my sausage fingers getting in there

Clean the earths and have a look at bulkhead plug to engine loom as on my 3.5v 8 the feeds come from starter and the bullet connector block can corrode.

Yep sounds like earthing problem.

Hi,
Out here with the landy now. So, problem is constant now. Removed all fuses and checked behind them. All ok. On removing indicator dip beam and full beam fuses, problem persists. No horn now. Clicking and buzzing from central relay. Windscreen wipers slow when trying to turn lights on. Regular speed with light switch off. Main feed from battery to gearbox fine. Indicator switch?
Sorry crap type, on phone

doynk said:

Hi,
Out here with the landy now. So, problem is constant now. Removed all fuses and checked behind them. All ok. On removing indicator dip beam and full beam fuses, problem persists. No horn now. Clicking and buzzing from central relay. Windscreen wipers slow when trying to turn lights on. Regular speed with light switch off. Main feed from battery to gearbox fine. Indicator switch?
Sorry crap type, on phone

Click to expand...

Engine to chassis earth?

Try using a piece of cable as a new earth by holding the cable to earthing points.

Can't find engine to chassis ground, sorry, bit of a novice trying my best. Will also try grounding cable trick

Try running straight from battery to dasboard.

doynk said:

Can't find engine to chassis ground, sorry, bit of a novice trying my best. Will also try grounding cable trick

Click to expand...

mines passenger side in block just above sump then out to chassis. in my limited experience, when 1 component plays up when another is switched on, its an earthing issue. when you find them, undo, clean both mating sides then bolt up tight. good luck.

Hi All,
a quick update.
i, for the life of me, could not find the problem so i took it to a garage here in France (first mistake)
They 'cleaning and repair ground wire setting up a ground wire between the body and battiere'
as google translate stated... i then drove home all working, and the lights went off....
on my way back to the garage this monring, again with no lights, buzzing, slow windscreen wipers, no indication when lights on, no horn etc.... the whole thing came back to life again... 50 metres from the sodding garage...
I asked:
can you find a problem when there isnt a problem?
Now theres a question.

still working this morning but im not chancing another dark drive up the mountain!
below is the road i drive up every night.... not fun in the dark.

if i ever find the problem, i will post it....

i'm also having problems! your central relay is the fog light inhibitor relay (as far as i know), which is part of the dip/hi beam system, as the fog light should go off when on high beam. so if this relay is playing up, it needs to be put right.

my problems are similar but i wanted to know before i go ahead taking the dash to bits, are there more relays behind the instrument panel?

i was putting a new wiper and fog relay in last night because my side lights wouldn't work, tail lights wouldn't work, fog light wouldn't work and only one headlight would work on full beam. at one point, i had the tail lights working, fog light working, hi and dip beam working and sidelights working. the wiper relay was the right one, but the replacement fog light relay was not. so after putting back the original relay the above started to work. all was well, then i tried to start the engine and got nothing apart from a click out of the fog light relay. and now all the lights work apart from the hi beam, with only one working again, this time the one that wasn't before!

my indicators are ok sometimes. left - they work properly. right - the left front flashes as well as all of the right hand ones!???? the opposite is true sometimes.

i'm about to go f**king ape sh*t and rip the whole lot out, but I don't think that would work either!

mainly could do with it starting so i can get it into my workshop!!

please help, thanks

Guys,

The sour news is no one on the forum can sort your electrical problems out, over the internet at least.

Sound electrical fault finding comes from a methodical approach through testing. The method you both are using is what we Technicians call "guess & mess"

As previously said by Jamo28 you both need a volt meter. i also use a durite power probe too, when the end is touching + it lights up red, - or 0v lights up green. start at one end of the circuit and using the diagrams work your way through testing as you go.

I am not trying to pull you both down but make you both think about your problems in a different way.

Doynk, you said your truck's lights jacked when going up hill in the dark, in other words when your alternator was working flat out. did you check the charging state? could my alternator be breaking down under load? did you check the battery voltage? did you check the coil circuit to the relay that was chattering. These are all the questions you should be asking yourself. check then rule out.

BigWill, are you aware that not all relays are the same just swapping things round is straight out of the guess and mess camp. swapping the parts of a circuit is not going to make another circuit work. if your side lights didnt work your question should have been: do I have power at the fuse, yes, do I have power at the switch, yes, do i have power at the relay and so on using the diagrams as you go.

Summary:

1. Testing tools, Volt meter and power probe. Learn how to use them, get on youtube watch the automotive circuit testing vids
2. Gain a understanding of the circuit you are working on (diagrams, freely available)
3. keep calm, walk away for a while (wood for the trees syndrome)
5. drink tea, the empire and land rover was built on cups of tea (tea and diagrams can be a great way of taking the heat out of the job)

Forget guess & mess and learn to do it properly, your confidence will grow and your fear will decrease.

regards
Lee

@doynk did you figure the problem out?

think i have the same

@bigwill did you sort your problem out?

mystery said:

View attachment 260290

Click to expand...

Cheers for the drawings.

Its not a bad earth as all is new and clean. the problems has not long come about and it gets worse as i was messing with the fog relay.

Have you checked header c287 or corrosion or oxidization of the terminal coating behind centre of dash