4 replies to this topic

[TrialsLife]

Hi,

I had a problem with one of the wires going to the coil on my 1969 mini cooper. Identified the bad wire and replaced it with a new tri-rated 4mm 40amp cable.

What I need to know is, is the wire I am using fit for purpose?

Do I need to install an inline fuse between the coil and the sorce of power?

Thanks,

Kyle.

[dklawson]

40 Amp cable? Really? My goodness that is large. If you were able to fit this cable in place... it certainly won't cause any problems. The coil circuit typically carries no more than about 4 to 5 Amps and that's not continuous.

However, I don't know when the Mini started using ballast ignition systems. IF the wire you replaced was going between the ignition switch and the coil (+) terminal... what color was the wire you replaced? If the wire was "pink/white" or pinkish in color, you cannot use regular wire to replace it. On the other hand, if the wire you replaced was "white", the wire you used will be fine. Regular wire can be used between the coil and distributor in any situation.

EDIT: Sorry, I forgot to answer about the fuse. In the applications I'm familiar with the coil was not fed from a fused circuit. It won't hurt to add an inline fuse, but in selecting one, choose a slow-blow variety. I would also base the fuse rating on nominal coil current x2, not the rating of the wire/cable that you are now using. I would say a 10 Amp slow-blow fuse would work if you want to add one.

Edited by dklawson, 02 July 2008 - 08:28 PM.

[TrialsLife]

As you can tell my spraky skills are poor, only have common sense at hand at the moment.

I was not sure what amp the coil ran at. I belive that minis run around 35 amp off where the battery terminal attaches to feed the car. I could see no fuse so just played it safe with the 40amp cable. I'm glad I know now, cheers. It would have been a white wire, unfortunatly the previous owner seemed to enjoy replacing wires with all the colours of the rainbow. So its quite difficult at times working out whats what.

I went to start the car just now and it won't go yet again, theres no spark, no reading on the fuel guage and no indicators or main beam. I'm going to purchase a multimeter (anyone point me in the direction for what I should be looking for?(price wise etc)). Hopefully that will help me find what part of the circuit is at fault.

I'm also going to purchase the appropriate coloured wiring for the car, and one by one re-wire the car. As I would like it all to be neatly placed behind the dashboard with an easy accsesable fuse box on the dash (compeating in road rallying so its handy).

Thanks for the reply doug.

Edited by TrialsLife, 02 July 2008 - 10:01 PM.

[dklawson]

I don't know which suppliers in the U.K. would carry the correct colored wires, however, you may wish to speak with AutoSparks. Not only do they have standard wiring harnesses, I understand they will also take on custom work. Presumably they would also be a source for the correct color wires should you choose to make your own.

The wire you selected will be more than sufficient for the coil circuit. In fact, you may wish to fuse it as you suggested. If that heavy gauge wire were to short to earth/ground, it will develop a lot of heat before it melts. The fuse will offer protection.

The coil power feed on the early cars comes directly from the ignition switch and traditionally was not fused. A multimeter will help you trace the wires to determine where you are loosing power. However, in a pinch you can always use a simple test lamp made from an indicator light bulb with two wires attached to its base. Over here, I would direct you to Harbor Freight Tools to buy a very inexpensive multimeter that you could carry in the boot of your car. Generally more expensive meters are better but for tracing auto wiring, the cheap ones are fine. I suspect that your Machine Mart stores will carry similar items to what I find at Harbor Freight.

Once you have the meter or test light you can work through the car's wiring using the standard wiring diagram. For the ignition circuit there are additional things to check once you know that power is reaching the coil. You may find it helpful to download the ignition system PDF I put together. There is a troubleshooting section in the document.
http://home.mindspri...tsIgnitions.pdf

[TrialsLife]

Thanks for the help. I'll have a look after work today for a multimeter and have a go at it.

Cheers.