Master Off

[twincamman]

had a lovely day motoring the country side in my 7 picking up switches and wire to repair another smoker behind the elan dash-- I= e/r-- [shoddy wire job-- my fault]--when I built the car I installed a master kill switch on the dash for just such an occurrence ---saved my bacon twice --suggest it to every one ---now rewiring CAREFULLY ed

[type26owner]

Hey Ed,
I've suffered through two major wiring harness burndowns and I've got a master cutoff switch too. The only shortcoming with having a master off switch is you only go for it when you smell the plastic insulation burning and by then it's too late your harness is toast. It will perhaps keep your car from catching fire and burning up though. That's a big check in the plus column.

Stick with it and you'll soon sort through the intial problems eventually. Just wait until you get it out on the track for the first time and you'll know why it's worth the effort.

[nebogipfel]

OK all you electrical gurus out there What about putting a big inline fuse in the main brown supply wire from the solenoid?

How big would it need to be to give adequate protection and yet blow before the loom fries?

[twincamman]

ok here we go-----I have deduced that by converting the car to a neg ground alt set up I have passed the fuse boxes ---- as lotus fused the positive ground side] of the circuit [ --that is to say the car now has no fuse protection as when a ground fault occurs the short is in a hot wire side and that Merrily continues to melt the wire ---as in no fuse to pop-----now i am now in the process of rewiring the car to be shorted at the wire that carrys power to the fuse -- not the ground wire -----having purchased 2 modern fuse boxes and many miles of colour coded wire I shall now proceed to bring the car kicking and screaming into the 21st century -- no 30 amp house fuses for me -- ed -------------------RELEASE THE KITE EGOR---I WILL GIVE IT LIFE ----

[twincamman]

well into it now--my friend George arrived to pitch in -- all the wiring is apart but have front and rear lights running and parking and flash to pass and hi low front beams-- tomorrow will add the new and improved fuse box and throw the old and corroded one very far away ---also will change the ground to the fuse box-----------bloody big job ----- :huh: ed

[M100]

twincamman+May 29 2005, 09:10 PM
ok here we go-----I have deduced that by converting the car to a neg ground alt set up I have passed the fuse boxes ---- as lotus fused the positive ground side] of the circuit [ --that is to say the car now has no fuse protection as when a ground fault occurs the short is in a hot wire side and that Merrily continues to melt the wire

To convert pos to neg earth (neglecting the repolarising of the dynamo or conversion to an alternator) you basically just reverse the connections to the battery, what was previously -ve feeding equipment (and fused) is now +ve (and fused)

So, what passed for fuses before on the +ve earth system does an identical job on the -ve earth system. Not saying that improving the fusing is a good thing but just that changing polarity properly doesn't put fuses on the "earthy" side of equipment

[twincamman]

yes thats what I thought to---but the smell of burning wires and copious amounts of smoke and heat convince me something else is wrong =----the fuses wont blow and wires melt ----Ive changed the ground to neg on the chassis and that should not effect the fuses --but something is wrong ---any ideas would be helpful ----although the dash is out and the harness is apart now----I'm still open to suggestions ---I had to reverse polarity on the tach--and added an alternator --everything else worked but these periodic meltdowns have me concerned greatly -- ed :unsure: THATS FERONKONSTEEN

[M100]

twincamman>
Ive changed the ground to neg on the chassis and that should not effect the fuses --but something is wrong ---any ideas would be helpful
If all the wires on the previous +ve terminal now connect to ground and/or the negative terminal then everything ought to be ok unless you have some DPO wiring

The tacho and the radio are the usual problems, the coil terminals need swapping too and the dynamo repolarising - (remove the F lead and briefly touch for a few seconds a live feed direct to the dynamo)

But once the harness starts going then its really time to rip it all out before anything big happens as fire can quickly start. A master switch is ok (got one fitted on my sprint) but by then its too late and damage can extend all over especially if you have dodgy earths.

I once rewired everything in the engine bay of a mini in a pouring rainstorm (before I had RAC Recovery) in around a hour using a cheap crimp tool, a few metres of wiring (all of one colour!) and a few crimps. It was enough to get home with the wipers, heater and lights and get a charge in the battery and bits of the reworking were on the car when I sold it a few years later. It was fortunate that I had the wiring diagram with me though as almost everything had gone to Lucas heaven before I managed to get the battery terminal off. The fault was traced to the original starter button solenoid feed "live" on the floor (this was a 1961 850) being removed and taped back when the car was "upgraded" some years previously to ignition key start.

[twincamman]

AH the DPO -- the car arrived in bits and boxes with the harness cut - no dash --the usual horror story for an old race car -- derelict and abandon --- <_< so armed with an old wiring diagram --a soldier iron and ohms law I set at it ---- ohms law always wins when a mistake is made so I m at it again ed

[twincamman]

actually blew a fuse so things are going well -- have head lights tail lights [front and rear] diff pump and fuel pump work and brake lights ---added new fuse boxs and a lead from the positive side of the battery to the fuse box so the ground works in front of the instruments - very little arc welding at all -ed B)

[twincamman]

tonight the signals-----luckily George stopped over and saved the day --rewiring the sig lights to one circuit took 3 hours and the outlook of Damocles [ sharp objects and fire etc] could not have done that one alone -------closer and closer - Kieth look at running a positive line of heavy gauge wire from the master off switch to the fuse box main in to put the fuses in the correct place in the wiring ed :wub:----WHICH BRAIN IS THE HEALTHY ONE IGOR ?

[twincamman]

its alive Eagor----job is done -----most everything works--but once you test the fuses they don't work very well the second time -- ed

[berni29]

On my plus 2 I used to have a cut out switch (big red key type) up under the dashboard next to the steering column. The main purpose was as a security device, but I also liked the fact that there was no current drain on the battery when the key was out.

[twincamman]

good idea ---mine is like an f 1 car to start --master on -check-fuel pump on-check ignition on -check-diff pump on--check --contact---push start rrr rr rrrrrrr rrrrrr rrrrr rrrrrr rrrrrr r-- r --r ---vroom ----ed