Electrical fault / short - Stop/tail side lights wont go off

Hi All,
Defender 300 TDI

I think its a short somewhere but no idea how to identify where.
My Stop and tail / sidelights wont go off even with the car turned off and the key removed from the ignition. I lost my headlights the other day but have not been to examine them yet. its an after market HID setup that i will be ripping out ina week or two to replace with LED's. The fuse on those seemed to have arced but the fuse isnt blown. Headlights just dont come on at all.

Any ideas where/ How i can trace down my short?

check you brake switch on back of pedal box

Bad earths all around me thinks. Re-made a few and some of the lights went out. Took it for a spin and the fault rectified itself but now i have lack of stop/tail amongst other things. Beginning to think this beast wasn't as good as i thought it was. Probably have to take it to an auto electrician to soft out unless some lovely member wants to school me in the ways electrical of a 300tdi.

twelsh37 said:

Bad earths all around me thinks. Re-made a few and some of the lights went out. Took it for a spin and the fault rectified itself but now i have lack of stop/tail amongst other things. Beginning to think this beast wasn't as good as i thought it was. Probably have to take it to an auto electrician to soft out unless some lovely member wants to school me in the ways electrical of a 300tdi.

Click to expand...

The lighting circuit on a tdi is about as simple an auto electric circuit as you can get. I would invest in a decent multi-meter, a heavy duty soldering iron (not an electronics one) and get hold of a copy of the wiring diagram (could get all for less than the cost of a specialist). You can then with some time methodically work through it matching the colours and tracing the routing teaching yourself as you go. I am not great with electronics but standard electrics I can now cope with having taught myself out of necessity. Auto electrician are expensive and defender lighting circuits are simple. You will save a lot of money in the long run by taking some time to follow the diagram and do some research on the forum and youtube. The only problem you will have is were prvious owners have cut it about and potentially bodged things or used different colour wires. When I first got mine half the lights were wired in using ring main cable it was rectifying that I then taught myself how it should all work..

Cheers Dag, I have the soldering iron and the Multi-meter. Just been using it in continuity mode and testing earths. I Have a copy of the Electrical circuit diagrams circa 1996 and Publication Part No. LRL 0126ENG Defender electrical wiring. I'll go have a go.

I have a similar problem to what you had originally. I have cut out most of the crap the previous owner bodged in. Now its a case of getting it all back and running right.

Thanks for teh post anyway

twelsh37 said:

Cheers Dag, I have the soldering iron and the Multi-meter. Just been using it in continuity mode and testing earths. I Have a copy of the Electrical circuit diagrams circa 1996 and Publication Part No. LRL 0126ENG Defender electrical wiring. I'll go have a go.

I have a similar problem to what you had originally. I have cut out most of the crap the previous owner bodged in. Now its a case of getting it all back and running right.

Thanks for teh post anyway

Click to expand...

It is fairly straight forward you just need to be patient and methodical.
One thing that is worth doing would possible help with your current problem is to put in additional good earth points. At places where there are multiple electrical items I have added earthing bolts. Where everything is wired to the same bolt and then the bolt is wired to a clean point on the chassis or back to the battery if near enough. This ensures that there is an easy path to earth rather than relying on the bodywork thus reducing the resistance in the circuit. This makes things easier for fault finding as you can eliminate earthing problems which in my expirnace make up 80% of all the electrical problems I have faced.

So the saga continues with my electrical troubles.

So lets start off with the nice new tool I have bought. A sealey PP100 PowerScope. Yes my Multi meter may have done the job but this enables me to power up endpoints with either positive or negative feeds. So to utilise this tool you need to hook it up to your battery or the cigarette lighter. As My cigarette lighter isn't connected I thought I'd use the battery connections. On Unbolting the seat, (yep previous owner changed the seats to bolted down ones so now I have no easy access to the battery) I found this...


Yep the idiot had wired in two batteries with no isolation. I was lucky my Missus wasnt set on fire I suppose.

This is how the battery box looked when i took off the burnt foam covering.


The fuse was particularly harrowing and i can see why it would have been a bot of a problem.

Completely melted. In cleaning up all the spurious wires etc I am now left with some semblance of order in the vehicle battery compartment. Though I still haven't gotten to the bottom of the electrical problems shorting out the external lights. More to come in the next post in a few mins

As I still have a list of outstanding electrical faults i thought I'd list them here first before going into what i have ascertained so far. Which, in hindsight, isn't very much.

1. No Headlights - Not a major problem. This will be due to the fuse burning out under the seat. That Red wire went to the HID headlamps that have been previously fitted. To be replaced with LED's next weekend probably.
2. No Fog Light
3. Sporadic indicators - Front and rear right work most of the time. Only left front comes on. No left rear
4. Stop/Tail not working
5. No reverse light.
6. No Horn. Works for a bit then dies/blows fuse.
7. Sidelights work fine. YAY!
8. Internal Light is Working. YAY!
9. Dash lights all OK. Well the ones that have bulbs. YAY!

Now according to my fuse box cover I have the following fuses in my Defender 300 TDI Circa 1999


On testing the fuses I see the following


Fuses 2, 11, are open circuits
6,15 and 16 were all showing negative polarity and recording a voltage of 0.0v
17 is a blown fuse
The voltage readings were taken with the vehicle running and the requisite switch in the ON/Activated position.

Im looking for some help to analyse the findings and ask where i go next with the probe to try and work out where the break / OC is on the wirig loom. Any advice?