My 1970 MK2 S has started blowing the fuse that is involved with the fuel and temperature gauges. The wiring in the car is original and on the face of it, in good condition.

Started about a month ago on a very hot day. Blew the fuse, put in a new one and immediately blew that too. A few days later I fiddled around behind the centre console looking for any obvious problem but there were non to see. I had a spare voltage regulator for the instruments so I replaced the original but didn't expect it to make a difference. Low and behold the problem seemed to be fixed and for the past month it's been fine. Then yesterday, another super hot day, blew the same fuse again. I replaced it twice more but they blew immediately. I should say here that the water temperature was fine and in both cases I continued to drive the car for the rest of the day without issue - just no fuel or water temp.

The manual I have here (the blue and white one) has a very confusing ( to me anyway) wiring diagram for the MK2 S ( could even be for the English MK2!) so I haven't had much luck figuring out what the problem is. I have looked in all the obvious places for burned or damaged wires but all good and there has been no burning smell.

Two questions really; what amperage should the fuse in a mini be? And, does anyone have any ideas on what might be causing the problem?

Would be very grateful for any help.

Blue MK2

My old van's alternator used to have a dud diode in the alternator, i found out after I pulled it out, and the voltage while the car was running was 14.8V, which is a little too high. I used to blow 1 of the 35 amp fuses every 3 mths or so, i can't remember which one. Ohms law, the more voltage the more current so my thoughts were the fuses were running on their limit and would blow every now and then.

Check your voltage while the car is running and make sure it's not too high..I'm presuming your running an alternator.

Cheers Shane

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If it's not a Cooper S, the mini was designed to be modified!

Thanks minivlt, sounds like what you say could have something to do with it. What I didn't mention earlier was that in both cases I was running in a Hillclimb and pulling high revs. Is 35 amp. The correct size fuze?

If it is your ignition circuit fuse that is blowing (Which should be 35 Amp) there should be a whole bunch of Green wires on one side of it. Disconnect them all and try re connecting them one by one with the Key on. Which ever wire blows the fuse leave off and then check what does not work from that circuit which will obviously be what works off that wire that you left disconnected. Then check that circuit through for the possible location of the short. Always start at the power source starts and work your way back. One most common fault..... Make sure the wiper arms have not been removed and placed back when the motor was not at park position .

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DID I MENTION THAT I AM THE BEST SUPPLIER FOR MINI ELECTRICAL PARTS AND REPAIRS?
"Let us remove your "SHORTS"

Thanks Convertable Mini, yes it is the fuse with the green wires. I will run a full test in the next couple of days doing what you describe but I think it might just be too light a fuse. Will report back later. Thanks again.

Blue MK2

I had a similar problem a while ago, kept blowing the fuse for the fuel gauge etc. What i found was that under certain conditions the 2 wires on the brake pressure switch would short out and blow the fuse. I ended up putting some better insulation over the wiring terminals to the switch and haven't blown a fuse since. Check it out, it is very close to the big nuts on the clutch actuation mechanism.

Diecast

Thanks Tony, that reminded me of a problem with the van and your advice solved it. Was the reverse light. Now to figure out how to wire it up properly. Or i could throw it in the bin.

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Dog Food! Most kids like it more than Broccoli.

Standard mini fuses are 35 amps (at least they used to be in 64).

I had a mysterious engine failure problem. The engine stopped and I found one of the main fuses blown. I fixed it and all was well for some time. but then it happened again ...and after a while again.

Eventually I found a wire had come off the stop light switch. After a bit of experimentation I worked out that if I was braking and hit a bump the wire would short, the fuse would blow and the engine would stop.....

Minis weren't meant to be easy...

Cheers, Ian

Off topic a little, but related

Could you not put say a 50 watt light blub in the place of the fuse to absorb all the excess energy which is converted to light instead of blowing fuses and when you have found the short it should glow dimmer.

I remember reading this in a 60's practical classics magazine

Never tried it just wondering if it would work

Kiwiinwgtn

Hang it from the bonnett and would make a great engine bay work light

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Dog Food! Most kids like it more than Broccoli.