Fuses

[Type28]

Hi

My Sprint still has the two fuse , fuse board.
Over the last two weeks the bottom fuse (25 amp) has blown twice - it includeds the fuel gauge, Rev counter, indicators and I think the brake lights in the circuit it protects.
Any idea what could be causing the failure?

Cheers
George

[john.p.clegg]

I would be smug and say more than 25 amps going through it,but that's the truth....you need to go around cleaning up all the bullet connectors etc and less likely look for faulty wiring earthing ( not as likely )

John

[bob_rich]

Hi George

fuel gauge and tacho are most unlikely to be able to blow a fuse.

Indicators and brake lights both take high peak currents when first powered. Cold bulbs draw a lot more current that there normal value once warm. Don't think this is the main problem. I would suspect corrosion in the light pod that may be adding a parallel path to take further current.

Does it fail occasionally or very time you operate an indicator or brake ? How does the fuse look is the wire just slightly cleared with a small gap or is it a really back deposit on the glass ?

Poor earths and bad connections tend to prevent a circuit operating rather then blow a fuse. I think you will be looking for corrosion or a damage wire that is shorting the voltage to ground. I would suspect a light pod

A trick I use is to temporarily replace the fuse with a bulb--when the fault occurs the bulb will light and then if the bulb stays on the circuit can be checked out to see where the fault is.

Hope this helps

best of luck

Bob

[lotusfan]

George

I have not been able to find a reference yet but I have a feeling that the fuses are 35 Amp not 25 Amp. Maybe someone else could comment on the normal value?

The Service Parts List says the fuses are 35 Amp so try fitting one and see if the problem goes away, if not fault finding as suggested is the way forward. Good luck.

[Type28]

Thanks for your thoughts on my problem. I found a couple of loose bullet connectors and pushed them fully home. I will clean up the rear light connectors as well. The fuse was heavily blacked were it failed( or worked however you want to look at it) The fault has happen twice since I changed the dash board, but the car has been used about twenty times since the dash change.
Would be interested to find out the correct fuse size.

Cheers
George

[Type28]

Back looking at electrics tonight.
New fuse didn't pop BUT I now have no dipped beam or brake lights. Also when I push the brake peddle when the indicators are on the indicators stop flashing the indicator bulb stays illuminated but dulls.

Bad earth somewhere?

I like fiddling with my cars, but electrics are not my strong point

Any ideas from people with more knowledge than me?

Cheers
George

[nmauduit]

electricity can be fiddly indeed... I would first look into what now does not work when it used to (including wire eaten away under the insulation ready to fuse out from reduced section, or broken insulator likely to create a short, e.g. near connectors). One way to get started could be to check connectivity (resistance) and path to earth of the incriminated wires, using a known good wire for the return, and proceed by elimination.

good luck !

[Type28]

Well that's the brake lights and dipped beam working again.
Stripped out the glove box insert, and the plastic covers under the dash. Pulled out all the wiring I had neatly put back and all was well.
Decided to tackle the dip beam first rather than assume they were both related. Traced the fault to the switch on the steering colum. I used a good quality switch cleaner to clean and lumricate the switch and the dip beam started working again, if it happens again I think I will change the switch.
The brake lights, well I firstly by passed the switch at the pedal and the lights didn't come on , I checked the bulbs and they were OK. I gave the bulb holders a good clean out with switch cleaner and they started working again?
So tomorrow I will check everything is still working and put the interior back together.

Thanks for all the advice

Cheers
George

[denicholls2]

A good tip I got soon after purchasing my Europa and re-entering the dreaded Lucas zone I'd happily left with the departure of my Spitfire decades earlier is to pull apart suspect bullet connectors, clean the bullet well, then apply petroleum jelly liberally before reassembling. Apparently it is good at blocking the corrosion these connectors are notorious for succumbing to. Worked well for me, anyway.

In the U.S., RD Enterprises sells bullet wiring repair kits for more distressed cases.

It's a non-original solution, but taking all of the high-current items (horn, headlights) and putting them on relay circuits instead of routing all of the power through the switched circuit as Chunky did makes your car safer and more reliable, if a tiny bit heavier. It will also make the unobtainium flash/high/low switch last longer, and it's not too difficult. You'll want the relays as close as possible to the load, which does mean running a fat wire to the front of the car as a bus that connects to separate wires feeding each device where to connect to the switched circuit for non-earth.

[Type28]

It will also make the unobtainium flash/high/low switch last longer

Didn't realise it was a hard part to come by- been getting used to Elan ownership- lift the phone to a supplier and the part you need arrives- not my usual Experience of classic car ownership

[billwill]

Recently while replugging the bullet connectors of my windscreen wiper motor for the umpteenth time I discovered that the bore of the 30 amp electrical strip connectors is just bigger than the wiring bullets and they can be slipped inside and the grub screw tightened to make a really reliable connection.

Not original Lucas stuff by any means for the purists, but I prefer reliability.