Earth Issue?

Here is a good one for you, its an electrical problem so I am doing my best to ignore it and hope it goes away.......

A little while ago the radio would turn randomly off and on again, generally if you hit a bump in the road. Its progressively got worse, bumps seem to make it worse but I can hit some potholes or rough road a a fair speed and it wont do it and then again when on a flat level motorway it will just turn off when I hit a cats-eye.

Its started to affect the headlights which will also flick on and off (well it might have affected them before, but as its now dark at night I am noticing it).

Strangely it seems to be worse when the engine is cold? Not sure if that's just coincidence or part of the issue. Likewise the more electrical things you use the worse it gets - i.e. if you have the heater on as well it gets quite bad. Again, I am not sure if its related or not, but the dash tell tail has just stopped working for the headlights too (full beam is fine).

I presume this is an earthing issue? My first plan was to try and clean up the earth - hows best to do this, a bit of wire wool and just a good polish?

Now without sounding totally useless.... where is the earth? I am sure I have been told its on the gearbox, but where abouts?

Are there any other causes? Google dosent seem to shed much light on similar issues.

What ever is causing it, get it fixed asap, you need a radio so you can turn it up to hide all the other really worrying grinding, clunking, crunching whining and squealing noise's.
Seriously though what engine/year is your Defender.

Scooby22 said:

What ever is causing it, get it fixed asap, you need a radio so you can turn it up to hide all the other really worrying grinding, clunking, crunching whining and squealing noise's.
Seriously though what engine/year is your Defender.

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So true, I have found so many other issues with it since not being able to hear my banging tunez through the (one working) speaker!

1997 300tdi 110 Station Wagon!

It might be worth checking the relays for loose or corroded contacts, or fuse contacts. I only have the TD5 wiring diagrams so cant tell you which is the most likely on a 300 tdi.

If the main earth from gearbox to batt was bad I very much doubt the truck would start. There is another on the engine to the chassis. Check the main power contacts at the starter solenoid.

I’d also be checking battery terminals, is the batt clamped down? Something is probably loose and you don’t want to end up with a short.

Scooby22 said:

It might be worth checking the relays for loose or corroded contacts, or fuse contacts. I only have the TD5 wiring diagrams so cant tell you which is the most likely on a 300 tdi.

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Good shout, I will take a look.

tottot said:

If the main earth from gearbox to batt was bad I very much doubt the truck would start. There is another on the engine to the chassis. Check the main power contacts at the starter solenoid.

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Its been (slightly) sluggish the last few times. I am not sure if that's my imagination or the fact its getting slightly colder. So where are all the earths? Would I be right in saying:
- Battery to gearbox
- Lights to the inner wings somewhere
- one near the clutch cylinders

Huddy84 said:

I’d also be checking battery terminals, is the batt clamped down? Something is probably loose and you don’t want to end up with a short.

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- You might have a interesting point there, we used to have a battery isolator fitted but I lost the key so took it off not so long ago which the issues started about a week later so it could be loose. Battery itself is clamped down. I am a bit concerned - the radio flicking on and off is annoying but not an issue, now its started affecting other things I dont want to break down especially with the dark nights.

and

mystery said:

and View attachment 192385

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That's brilliant, cheers! Is that the workshop manual?

The earth should be on the chassis behind the battery box, you will need a wire brush or rough glass paper, it could also be the cable connections , there will be one to the gearbox and one to the engine but its usually the one from battery to chassis that gets bad. Do you have a multimeter?

mystery said:

View attachment 192387

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Ah thats really helpful thankyou. I have heard stories about there being one in each wing for the headlights - is that just older models?

nobber said:

The earth should be on the chassis behind the battery box, you will need a wire brush or rough glass paper, it could also be the cable connections , there will be one to the gearbox and one to the engine but its usually the one from battery to chassis that gets bad. Do you have a multimeter?

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I do indeed, electrics are not my greatest strength mind.

The end of the loom to the front lights has a earth ring that connects to the inner wing on both sides...

swisstoe said:

The end of the loom to the front lights has a earth ring that connects to the inner wing on both sides...

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That wont be connected to the radio though. This is either a main earth or live, first thing to notice is the radio, its on all the time usually, next would be lights at night because they are so obvious but not as obvious as the radio, neither share the same earth so it has to be battery earth.

19_Hue_95 said:

Ah thats really helpful thankyou. I have heard stories about there being one in each wing for the headlights - is that just older models?



I do indeed, electrics are not my greatest strength mind.

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Because radio and both lights are affected I very much doubt its a live issue, both headlamps will be on separate circuits and the radio wont be on a lighting circuit, unless it lights up with the side lights? Follow the battery earth to where it connects to the vehicle, test the cable for continuity, wiggle it at its connections as its an intermittent fault, clean the area that it connects to, another thing to try is when it happens put the wipers/heaters/anything on, if they stop working also then you know its a main live or earth problem and not deeper into the wiring harness. On the live side I would start with battery live both ends and engine harness to main harness connecting block.

nobber said:

Because radio and both lights are affected I very much doubt its a live issue, both headlamps will be on separate circuits and the radio wont be on a lighting circuit, unless it lights up with the side lights? Follow the battery earth to where it connects to the vehicle, test the cable for continuity, wiggle it at its connections as its an intermittent fault, clean the area that it connects to, another thing to try is when it happens put the wipers/heaters/anything on, if they stop working also then you know its a main live or earth problem and not deeper into the wiring harness. On the live side I would start with battery live both ends and engine harness to main harness connecting block.

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That’s excellent help thank you. It’s along the similar lines to what I was thinking, I have studied the circuit diagrams and noticed that the affected items (there may be others, but like you say there the most noticeable ones) are on different circuits which is what had me stumped. So the battery earth looks to be the culprit (and it seems quite a common issue). I am going to start with the earth as that seems to be the obvious culprit. I hoping it’s not something more complex – though I doubt it as I have not (and neither has anyone else) touched the wiring so it should in theory be limited to a corroded connection somewhere.