Virtually all electrical system gone.....!

[Owlsman]

In preparation for me fitting a hazard warning flasher system on my '62 saloon with a DB10 relay, I bought some LED dual purpose front side lights bulbs which I was hoping would show a standard white light for the sidelights and an amber light for the indicators. (I have already fitted an LED lightboard at the rear to give me flashing amber indicators).

I removed the front lens cover and existing bulb and replaced it with the new LED. I switched on the sidelights and all was well, as the new bulb lit up brightly. I switched off the lights as I wanted to check the amber sidelight function. I switched on the ignition.......but nothing! No power to the ignition, no interior light, no side or headlights, no horn, absolutely nothing! As far as I can tell the only thing that works is the pull starter.

The obvious thing (to me at least) was to check both fuses, although I do know that most of what was not functioning is not fused. Both fuses seemed in tact but nevertheless I cleaned up the ends and re-fitted them, even replaced both with new fuses......still nothing!

My car is fitted with an alternator - actually, a Dynamator, which is only an alternator in a dynamo casing.

I really don't know where to start. All I was trying to do, was change a bulb!! Any bright ideas folk as any help would be much appreciated please?

Thanks in advance.

[unclealec]

Check the input and output at the ignition switch to make sure the switch itself hasn't failed - they do sometimes. Also ensure that the battery terminals are clean and tight.

[oliver90owner]

Check the input and output at the ignition switch to make sure the switch itself hasn't failed - they do sometimes. Also ensure that the battery terminals are clean and tight.

If the starter motor is working normally, the battery terminals will be secure and the battery is demonstrated as adequately charged.

It does seem that the ignition circuit has been disconnected - but that does not include the lack of lighting. A test lamp or multimeter would be good tools for investigating where the battery supply is disconnected from the wiring loom…..

[unclealec]

Check the input and output at the ignition switch to make sure the switch itself hasn't failed - they do sometimes. Also ensure that the battery terminals are clean and tight.

If the starter motor is working normally, the battery terminals will be secure and the battery is demonstrated as adequately charged.

Still worth checking imho. The number of times I have solved a seemingly puzzling electrical problem by remedying problems with the terminal connections, I always do a quick check, though I agree with you that the starter performing would indicate otherwise. The power pickup from the upstream solenoid terminal is also often problematic; I usually give that a clean as well.
Having used the starter as an indication that the battery itself is OK, it's a case of chasing the volts using a meter or even a test light.

[geoberni]

It's the total lack of electricity (to circuits other then the direct Pull Start) that is puzzling me?
The un-fused Lights and Horn, should always work.

Because it's a Dynamator conversion, the way that has been connected may be a factor.
Was the original RB106 left in place as a junction box, or was one of their Dummy Boxes fitted?

The Dummy Box includes a 40A Fuse; depending how those are constructed, perhaps it also includes the previously un-fused systems?

[simmitc]

I believe that you should have a heavy duty cable from the battery to one terminal on the starter switch. From the same terminal should be a thinner, but still relatively thick, brown wire to the dynamo control box terminal A, assuming that the DCB has been left in place as a junction box. If that brown wire has been misplaced or broken then it will cause the symptoms that you describe. On the starter switch, there should be another heavy duty cable from the other terminal to the starter motor; and only that cable should be attached to that terminal. Using a meter, check for voltage at the A terminal on the DCB.

[Owlsman]

Apologies gentlemen if I appear to have been rude by not thanking you or even acknowledging your input but I have been in bed for the best part of 2 days feeling really rubbish with a stinker of cold (proper man flu?) and only this afternoon dragged myself into the garage to check out your suggestions.

I am most grateful but the bottom line is, I am no nearer to solving this problem. There are only 2 black wires attached to terminal E of the DCB and no other terminals are in use.

I do have a multimeter but truth be told, I don't really know how to use it! All I've been able to do is have a good poke round in the engine bay, to see if anything obvious had detached itself somehow. Nothing leapt out at me. One of the reasons I got up at all today, is because it's the local area club Christmas bash tonight, which has all been paid for. I feel I might have throw myself at someone's mercy and see if a fellow member might be able to call round and sort me out.....and perhaps the car too!

Thanks again for you thoughts. Whatever the problem is and whenever it is solved, I will get back to reveal all.

[simmitc]

If the DCB is not in use, then there must be another form of junction box, perhaps a "chocolate block" connector?

If you can post photos of
a) Your multimeter
b) The bulkhead of the car showing the area between the battery and the right hand side of the car
c) The Dynanator back to the area (b)
Then we might be able to advise further.
It is almost certainly the brown wire that provides the power but if it is not going to the DCB, then follow it to where it does go.
Hope you enjoy the "do".

[Owlsman]

CRACKED IT............Well, at least the reason, if not the cause!

Not too long after I bought my Moggy I (with advice) fitted a voltmeter. I used suitably thick cable and ensured it was well protected against chafing as it passed through and back out of the bulkhead. I was also advised to fit an in-line 30amp blade fuse as a bit of extra protection/security. IT WAS THAT FUSE THAT HAD BLOWN hence the virtual shutdown of all the electrics.

After I replaced it it was like Blackpool illuminations again! OK, I am prone to exaggeration!

I was somewhat reluctant to try and refit the new LED front sidelight at first, so I tried the standard bulb, which worked fine as a light and an indicator. .......and nothing fused. Whoo Hoo. I risked replacing it with the LED jobbie and that too works exactly as I'd hoped i.e. white sidelight and amber indicator (with the ignition on of course!) Double Whoo Hoo.

My only questions now are : Why would a 30 amp fuse blow? Is it a myth that fuses, just like me, can get a bit tired? Is it possible to insert an LED bulb incorrectly to cause it to blow?
Obviously, I'm chuffed that everything's working correctly again but I'm left a tad nervous because I don't know what caused the fuse to blow in the first place. Anything to allay my nervousness chaps?

[simmitc]

I'm glad that you got it fixed, but do not understand why you need thick cable and a fuse for a voltmeter, or why you would wire it so that everything flowed through the voltmeter. Do you really mean a voltmeter, or is it perhaps an ammeter (amp meter)? Whichever, if you had provided that information, then we would have probably given different advice. It is important to provide all relevant information. I suspect that if you had followed the wiring from the starter switch, then you would have reached this additional fuse
The fuse is likely to have blown because you shorted a supply wire to earth.

[oliver90owner]

The fuse is likely to have blown because you shorted a supply wire to earth.

Almost certainly the lighting circuit was shorted to earth - it’s not on a fused supply, until you added one.

[geoberni]

Not too long after I bought my Moggy I (with advice) fitted a voltmeter. I used suitably thick cable and ensured it was well protected against chafing as it passed through and back out of the bulkhead. I was also advised to fit an in-line 30amp blade fuse as a bit of extra protection/security. IT WAS THAT FUSE THAT HAD BLOWN hence the virtual shutdown of all the electrics.

My only questions now are : Why would a 30 amp fuse blow? Is it a myth that fuses, just like me, can get a bit tired? Is it possible to insert an LED bulb incorrectly to cause it to blow?

Well I'm glad you've sorted it.

I've highlighted these two aspects of your post as they are points of interest.
A voltmeter doesn't require thick cable, nor should it need a fuse. There should be negligable current going through a voltmeter.
If that was included in the advice you were given, then it was wrong.
You should not be pulling circuit supply through a voltmeter... The Voltmeter is always in parallel with the load.
You said :

I switched on the sidelights and all was well, as the new bulb lit up brightly. I switched off the lights as I wanted to check the amber sidelight function.

I assume you mean Amber Indicator, but the fact that the sidelight had worked would imply the lamp was fitted correctly.
It might be the lamp is somehow faulty, but it's your wiring of the Voltmeter/fuse that concerns me ....

Secondly, Fuses can get 'tired', ONLY if they are repeatedly taken to their limit or momentarily over it, for decades. Eventually they'll declare 'enough is enough'.
My house is about 35 years old, the garage (probably for slight cost reduction by the builder) has a small Ceramic Fuse Box, with actual Fuse Wire to provide separate Lighting and Socket facilities.
I've never had reason to change a fuse wire. Fuses will last forever if not abused by over stressing.

[Owlsman]

Thanks very much for your input chaps....apologies for leading you astray.

NUMPTY ALERT: You are quite right Simon.....the fused thick wire was to the ammeter NOT the voltmeter. In my (very weak) defence, I do have both and they sit side by side in a double bracket. I know!! Also, it was only when I was laid in bed pondering, did I have this vague recollection of fitting an in-line fuse somewhere.

I'm not too ashamed to admit that I now know exactly what happened. As I was halfway through fitting a NOS chrome o/side rear light base (to replace the rather pitted one I had) there were 4 wires all with bullet connectors, simply pushed through the hole in the rear wing. I got called in for tea or something and then later, my new LED front sidelight bulbs arrived. In my haste to see if they were a) the right bulbs and b) if it was indeed a white sidelight and amber flasher, I forgot about the half finished job at the rear. Obviously, as I opened the door and reached in to switch on the lights and then the ignition, it was just enough for the now live rear light wire to touch the earth wire and........the rest you know!

Perhaps my wife is right...maybe I shouldn't be allowed out on my own, without a grown-up?

Just one question remains: if the cable to the ammeter had not been fused, what could the consequences have been? I.e. burnt out wiring somewhere? Worse?

[oliver90owner]

what could the consequences have been? I.e. burnt out wiring somewhere? Worse?

Yes, is the obvious reply. Too much current in a conductor will heat it to the point of melting the insulation. Further heating could lead to a fire.

[simmitc]

Ah well, everything resolved, no harm done. It takes a a lot to admit making a mistake. All's well that ends well

[panky]

It's a bit late to help you but I had the same issue when I lost all power in my Commer camper on a petrol station forecourt I couldn't work it out but a temporary wire from the battery to the fusebox got me home. Took me ages to work out what the problem was as the ammeter simply failed without warning.

[olonas]

I had similar happen, i.e. loss of all electrical power. All I had done was drive into the garage and start to check the lights with the engine still running. I switched on the headlights and everything died! It's a "pull" starter switch and the engine turned because of the direct battery to starter via the pull switch.
When I had fitted an ammeter, rather than run new cables, I used an inline modern connector plug and socket. For whatever reason, that had failed. It did take some head scratching, choice language, etc. to track it down.