Blue cable in front

[Uboat]

Hi,

I'm having some electrical problems, as a fuse (second from left) in the fuse box on the dash keeps blowing. I have just gone through the earthing points, and I can't find the culprit.
I have also found a loose end of a blue cable coming out from the front right wing cable tunnel into the nose cone (I have a late LHD +2 130/5). As I recently fitted a new air filter kit, I suspect I touched this wire by mistake so it became loose. What is this cable good for ? I can't find any blue wires on the wiring diagram...
Anyone got a clue? it is much thicker than the other cables

/Ulf

[alexblack13]

Sounds like it could be a non standard cable. It could be supplying an earth to somewhere perhaps, or it could be a rewire, bypassing a 'fault'. Not all repairs were to a prof' std. A repairer would not care less what colour of cable he used as long as he got the fault 'repaired'
and the electrical item working.

I counted 9 'scotchlock' connectors and extra cables various (One of which had nearly caught fire!!!) when removing the old wiring loom from my car. Speaks volumes...

See if you can follow it back to find out where it comes from.

What does the blowing fuse support?

Alex B.....

[Frank Howard]

Ulf,

Don't know if this applies to your car, but when you install a modern radio, the blue wire coming off the back of the radio is the signal wire that goes to the power antenna telling it that the tuner is on. It tells the antenna it's time to rise.

[Uboat]

I just tried again with a new 35 A fuse, and I could litterarly see it burn in two seconds. I have had some minor electric problems before, such as an erratic fuel gauge, and recently the ignition warning light has been activated also when driving and idling...

[types26/36]

Looks like a non-standard wire to me........has it got a switch inside? could the wire be for a fan overide?

[Uboat]

No switch, the cable is not as wide as it looks in the photo. It is cirka 3 mm

[alexblack13]

You need to trace where its connected to. It could be a red herring and nothing to do with your blowing fuse. If this is the cable which is trying to burst into flames, then the fact that it is not connected at the end in the pics, means that it is shorting to earth somewhere. Did this problem arise after you did the work you said you did (airfilter etc). Was all ok prior to??

Very non standard cable though. Not unusual in an old Lotus.

Hope you find it soon & keep the big fuses out till you have found it. V carefull here....

Alex B....

[alaric]

Hi. You need to get yourself a little digital multi meter. I bought one many years ago from maplin, but I think you can get them from the like of B&Q now. As I'm putting my wiring into my +2 - same model as yours, I'm checking the resistance between +ve and earth before hooking up the battery each time. I'm also able to verify that I'm connecting the correct wires without needing to look too closely at the wiring diagram - the colors are slightly different so can't be relied upon. Mine's got a continuity beeper too, so if I'm looking for where a wire connects to I can just whiz round all the candidates quickly with the probe.

On the wiring diagram it would appear that the brake lights and fog lights are driven by that fuse - assuming the order of the fuses is the same in the diagram as looking at the dash.

All the best.

Sean.

[Uboat]

I have spent the last year learning about suspensions , breaks and other things, but my knowledge abut car electronics is still close to zero. Is there any free beginners guide on the net? How do I find the short circuit? How do I reach the back of the fuse box and the connections to it? I guess I need to get this instrument...

[alexblack13]

I am with with Sean 100%. I assumed you have a multi meter. If not, go and buy one, It will help all the way thro' ownership of your Lotus.
Buy the best you can afford. Quite a few good quality s/h for sale on Ebay for E.G.

Good hunting & don't fret. You will find it.

Alex B...

[neilsjuke]

I would use a inline fuse remove the earth lead and fit between the lead and battary (you can also do this at the solinoid large brown wire easy if it has a lucar type terminal) amps depends on what load you are putting on but 25 amp will blow if you get it wrong and will stop you burrning the loom .

http://www.flickr.com/photos/16638375@N03/3655984701/

You will see from the pic I have the inline fuse holder (History for me made it when served my time as a sparks for Lucas in 70s) and MSB type saves on fuses. When I got my elan the first thing I did was rip out all the DIY wire fix the faults and saved weight from all that copper.
Neil

[alaric]

Hi. I've just checked on the Maplin site for multimeters:

http://www.maplin.co.uk/Module.aspx?ModuleNo=37279

That's a crazy low price at ?6.99

The accuracy spec on the unit is probably more than enough for debugging these cars. The one I have is over 20 years old, cost i think ?35 and probably doesn't have any better functionality.

Re idiot's guide to debugging there's probably lots on the web, but the first check you should do is take out the fuse, put the positive lead onto the output side of the fuse holder, and put the black lead onto the blue wire in the engine bay - I find with my dmm sat on the windscreen, the leads do actually reach round through the door. Then you can check using the resistance meter whether or not it's connected to the blue wire. If it is, then connect between the blue wire and the chassis to see if it's a short. And so on. I use mine with the buzzer on so I don't need to look at the screen. I don't think you need to get behind the fuse box yet.

With it set to measure volts you can measure the volts all over the place to see what's going on.

Hope that makes sense.

All the best.

Sean.