No Lights - Blown Fuse...

[Jon Green]

Hi All,

 

Whilst out for a spin today I switched on my fog light only for it to blow the fuse. Turns out that all my lights were fed through the same 3 amp fuse so they were all lost. Fortunately not a problem as it was only a brief bank of mist.

 

On further investigation tonight I've found that the 3 amp fuse supply's 3 wires in the column switches. A red, a black / brown and a chunky black. They're 1983 sierra stalks.

 

I'm guessing that these live feeds should have separate feeds and fuses so this can't happen?

 

I could have been in the s**t if it'd been dark!

 

Jon

[fry61]

Have you checked to see if your car lighting circuits have relays ? A 3 amp fuse would be O.K for the fog only --it needs around 2 amps & head/side lights need at least 12 amps.

 

Best practise is for your lights to be split port & starboard,with main/dip beams on relays; so a problem will still leave some front/back illumination.

[Longboarder]

It's difficult to know how your car is wired up. Did you build it? Did you buy it from the original builder with a wiring diagram. Was it built with wiring the same as the donor or just invented out of the builders head. To get anywhere with this you need to investigate further to see which terminals on which column stalk these wires go to or you won't know their intended functions.

If your car was wired like its donor:-

Red is intended as a constant live. Often connects to a terminal numbered 30. (Possibly right stalk 30)

Black is intended as an 'ignition on' live and often connects to a terminal numbered 15. (Possibly right stalk 15)

Brown/black (on some cars could be black) may be intended as 'ignition on' supply. (Possibly left stalk 15). Could also have other functions!

None of these was fused before the stalks in the donor. Ford decided to fuse lights functions after the column switches. (Horn, washers, wipers, indicators were all fused before the stalks.)

Many owners used relays controlled by the stalks to reduce electrical loads on the stalks. Many split circuits left and right after the stalks (or relays if they had them) and fused each side separately so they would not loose all their lights.

 

Fog lamp(s) usually piggyback off the link wire between terminals S54 and 56 or the link wire that joins these two terminals, adding its load to the light supply and sounds like this was the straw that broke the camels fuses back in your case.

 

It may also be helpful to remove the fuse that blew (remove it if you have replaced it) and test what other functions controlled by the stalks are still OK or also missing. Check wipers, washers, horn, indicators, headlamp flash.

And report back if you can with more information.

 

Nigel

[Jon Green]

Thanks for the responses chaps,

 

I built my car 11 years ago and wired it with the help of my dad who's a sparky. We mostly followed the sierra haynes wiring I think though i'm not entirely sure.

 

I have two relays for the lighting, 1 for the headlamps and the other for main beam.

 

The 3 amp feed to the column stalks feeds;

 

On the wiper side, right :

 

Red pin 30

Black pin 15

 

On the main beam side, left;

 

Black and Brown pin 15

 

Haven't got a another 3 amp fuse to hand so i've popped a 20 amp in..... though I will swap it for a 5 amp asap.

 

Nigel, you mention that some of these supply's aren't fused before the the column so should I be leaving the 20 amp fuse in place and adding in some lower amp fuses after the column?

 

And what's the best way to split the lighting feeds up so that I can't have a total failure again? I guess that if I feed my brown / black wire separately I'd at least have a main beam flash even if power to the right-hand side of the column failed?

 

Help appreciated! I'm just getting back into driving my 2b after a extended period of it being laid up due to a baby and associated pressures on time and finances. He's 7 now so it's about time it came out of the garage again!

[Longboarder]

Yup. It's a copy of the old sierra. This is how I did mine to separate the various lights into left and right sides so the loss of all lights if there was a fault was unlikely.

Sides come direct unfused from battery to column switch and then to fuse box where they split left and right through individual fuses.

Supply to terminal 30 on the relays also direct from battery unfused.

Ignition live then supplies the terminals 15 on the two column switches and out to switch the relays. Relay outputs go on to pairs of fuses.

(The diagram also shows the S54 to 56 link wire which is often tapped into for the supply for the fog light as it's only live when the headlights are on.)

 

You can stick extra fuses in if you wish but they are going to be bigger than 10 bearing in mind the loads downstream.

 

As these three wires also support the side lights, numberplate light and probably the fog light as well as the two relays. 3 amps was not enough.

The red wire to 30 on the column switch should not be linked to the ignition lives. It's a battery live.

The black and the black/brown are both ignition live and can share a fuse. 15 would be ideal if you wanted to put an individual fuse there.

I'm assuming the power supply to terminals 30 on the two relays is separate.

 

Nigel

 

You can add fuses to all sorts of circuits, in supplies, in switch outputs, before or after relays, etc. Bear in mind the fuses all need to be in one or two fuse boxes in sensible places you can get at which means wiring to and fro to the fuseboxes. Don't scatter inline fuses in distant arms of the loom. You will forget where they are and never find them when trouble-shooting.

Edited November 27, 2016 by Longboarder

[fry61]

Snap to Nigels last paragraph -- an in-line fuse under Florin's scuttle was the only place to wire the last piece of loom & was the first & only one to blow " on the road" so far (touch wood/fingers crossed )