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Land Rover Diary

Part Seven: A Fog of indecision.

First Posted: 23rd Aug 2010 20:31

So, back home from work this evening, and the thought of that rear fog light is bugging me.

If you have read the tales so far, you will know that I spent a little time on Sunday afternoon deciphering the wiring diagram, to try and find the reason why my fog light doesn't work.

I had tested the wiring in the light unit, and found there was no electricity making it as far as the light fitting.

I then found, from the diagram, that there was a relay in the circuit somewhere. Well actually, not a relay, an "ECU". Being semi-educated I worked out that ECU stands for Electronic Control Unit, so I felt a lot better for knowing that... (know thine enemy!)

However, Mr Haynes does not tell me where the ECU is located. I do not have a workshop manual yet, and there is no owners handbook either.


Ok, first things first, I take the lid off the fusebox, and, knowing that the fog light is on fuse 6 (it says so on the lid) I pulled the fuse and tested it with my meter.

Oh, good, it's fine...

So then, I dismantle the fusebox to get at the relays at the back. I sit and stare helplessly at the little square boxes, hoping one of them will have FOG ECU emblazoned on it, but no such luck.

Mr Haynes doesn't actually tell you which relays are where, not for my model of vehicle. It does for 2002 onwards, there are some very pretty pictures, but for a 1997 - or even 1991 to 1996 (which is the only diagram I had to work from) there is no clue.

Eventually I get bored prodding things, and re-assemble the fusebox and put its lid on.


Then I went and found a computer, and started googling. After being sidetracked by various interesting things I didn't know about Land Rover wiring, lighting, and relays, I found a page which told me where the ECU was located.

It's behind my old friend, the instrument panel.


Back to the Landy.

Me and the instrument panel have become quite well acquainted recently, after my forays into the matter of speedometers, and why they don't work, and I have become quite proficient at removing it, so in no time at all I had it shoved to one side so I could look at the writhing mass of wiring that it harbours.

The web page said I would find the ECU attached to the bulkhead above and behind the location of the speedo, and sure enough, there it was.

I got the trusty multi-meter, found an earth, connected the other meter lead to what was supposed to be the output of the ECU and started the engine. Then I turned on the lights and pressed the fog light switch.

Drat! Electricity is here!

Okay then, now what do I do?

I decided that the next port of call would have to be the back corner where all the wires from the harness re-appear from the chassis after their journey from the front of the vehicle.

A previous owner has made a very good job of lining the whole of the interior of the back of the Landy in 3/4" marine ply, and I did wonder if he had considered the needs of an amateur electrician, or whether he had blocked up all access to the wiring. I found a very neat little box affair, with some obvious screws to remove the lid, god-bless-him!

I dug out the red and yellow wire from the spaghetti therein, and found the bullet connector to the fog light unit - which parted in my hand...

I reconnected it firmly.

Then I went and started the engine, turned on the lights, and pressed the fog light switch. I approached the back of the vehicle... As the rear door was open, I could see a warm red glow reflecting off it...

YES, a working fog light!

I tidied up the wiring (well, shoved it back in the box) and screwed down the lid. The fog light didn't flicker once...

I turned off the lights, and the engine, then I put the instrument panel back together (until next time!).

So, mentally ticking another item off the list, I return to the computer, so I can tell you all about it.


Next time...

Well I don't know yet, it depends...



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