Fuse box Replacement

[Adrian]

Hi all

The investigation continues. Your starter for 10........Attached is what fuse relates to what. It doesn’t seem to full comply with the previously posted diagram with some components being doubled up. Fuse 4 and 7 don’t seem to do anything, I’ve put the wire colours on if that may help.  The next thing is the heater fan, should it be perminantly live and unfused as this is what it currently is.

with the exception of the heater does it really matter what is fed by what provided it is fused ok. Not sure if the parking lights are connected which may account for one of the unknown fuse. 

Cheers Adrian

[NonMember]

On the original wiring, the heater fan is powered by the green circuit - ignition switched and fused.

The brown/purple fuse is originally the (permanent live) fused supply to the horns, hazards, and other stuff. It looks like you've got three separate such circuits but they're not distributed as well as they might be.

[Paul H]

Heres the layout of the 2 fuse boxes for my Vitesse - I upgraded the fan to one from a Micra  , added a relay and chose to connect to the battery fuse box - The logic being I could cool down the heater matrix if stuck in traffic with the engine off . Pretty sure some of the fuse ratings can be tweaked 

Paul 

[Badwolf]

Hi AidanT - Just getting around to emulating your excellent project but before I start, can you tell me how you created the busbars for the 12v in. I assume that you linked all the centre contacts together and fed them from a single 12v feed. Did you just solder/wire the contacts together or run a strip of copper along. Also how did you insulate the 12v to prevent an accidental short. I think that everythng else is covered in tbe thread. Any extra pictures of the back would be useful please.

[SpitFire6]

Something like this?

[Badwolf]

Got the same one as Aidan

from Vehicle Wiring Products but all the terminals are individual hence the need for the 12v busbar for each side.

[dougbgt6]

I didn't use a separate busbar. I designated the 3 original fuses red, purple and green. Red and purple each had 3 wires hanging off them and green 4. Which handily adds up to 10. I wired the upper connections on 3 fuses on the top together and three on the bottom, then the remaining top 2 and bottom 2 together. I used solid copper wire I'd stripped from a heavy cable for the interconnection. To be honest it's an odd selection of things to be fused together, horn and hazards? Why are there separate connections for the wiper motor and wiper motor park?Starting from scratch I would have done it differently, but that's the way Triumph wired it. Plus it has the advantage that you're not messing with the loom, just the fuses.

 

                   

 

Here is the diagram I keep posting on here. It's slightly off, the side lights DO physically connect at the red fuse not the instrument lights. And the green fuse has only 4 connections on my car.  My heater fan comes off the ignition, ie the TOP of the green fuse! Why? You could only make 4 connections to the top and bottom of the fuses on old fuse box? Whatever, a separate in line fuse for that. (10amp).

Doug

[Badwolf]

Thanks Doug. Yes, I saw the original posts. I was wondering about insulation of the 12v feed at the back of the box in case of an accidental short. I think daisy chaining insulated Lucar connectors was dismissed as messy but I was just wondering how others had done it, or just left it to chance. I just have visions of finding the back of the box while poking around with a screwdriver and shorting the positive side of the back of the box to earth.

[dougbgt6]

My daisy chain is quite neat, wire wound round the base of each connector and soldered, you wouldn't notice it's been done. The fuse box is directly behind the glove compartment so no reason to be poking about there. The fuse box does stick out at the back a bit more than the old one and the glove compartment (cardboard!) needed a little slight manipulation to avoid touching the loom. And if you're poking about you should've disconnected the battery!!   I've got one of those battery isolator thingies, £12 from the club shop.

Doug

[Badwolf]

Ok, thanks. I'm looking at the 90 degree female lucar connectors either crimp or solder (preferred),to give a little more space behind the 'glove box'. Also thinking of adding a cigarette lighter connector inside the 'glove box' to power phone, tablet etc. Probably off a perm live link. Did you use piggy back connectors for anything or just one single per connector blade?

[dougbgt6]

No piggybacking, it worked out quite neatly at one connector per blade. There was even a space for the headlight feed (which is separately fused) off the top of the purple fuse. 

The troublesome bit was enlarging the fuse box hole, it only needs to be slightly bigger as the original box has the engine bay loom going through it. You have to separate the grommet and loom from the old box and cut a new hole for it. I put mine right up against the fuse box hole so that it's squashed up against the new box and there's no gap in the bulkhead.

Doug

[Badwolf]

Yes, I read about moving the grommet etc over and making a larger hole. Just wondering about the best way of adding anything extra like an additional power feed to the cockpit without making a total rat's nest of connections, but it looks like its not too bad.  As usual, probably over thinking the problems so nothing nasty happens when I set to with the cutters and hacksaw.

[dougbgt6]

Some Spitfires have a cigar lighter which comes off the purple fuse group, but I'd want something a bit more universal and I'd run it separate from the fuse box with an in line fuse.

Doug

[rlubikey]

I left the old fusebox in place (for show) and moved all the cables over to my new fusebox in the passenger glovebox.

Cheers, Richard

[dougbgt6]

Cunning!

db

[s99sdp]

4 hours ago, dougbgt6 said:

I didn't use a separate busbar. I designated the 3 original fuses red, purple and green. Red and purple each had 3 wires hanging off them and green 4. Which handily adds up to 10. I wired the upper connections on 3 fuses on the top together and three on the bottom, then the remaining top 2 and bottom 2 together. I used solid copper wire I'd stripped from a heavy cable for the interconnection. To be honest it's an odd selection of things to be fused together, horn and hazards? Why are there separate connections for the wiper motor and wiper motor park?Starting from scratch I would have done it differently, but that's the way Triumph wired it. Plus it has the advantage that you're not messing with the loom, just the fuses.

 

                   

 

Here is the diagram I keep posting on here. It's slightly off, the side lights DO physically connect at the red fuse not the instrument lights. And the green fuse has only 4 connections on my car.  My heater fan comes off the ignition, ie the TOP of the green fuse! Why? You could only make 4 connections to the top and bottom of the fuses on old fuse box? Whatever, a separate in line fuse for that. (10amp).

Doug

I'm sorry if this is a stupid question, will this diag be suitable for my my 1970 Mk3 Spit? I've seen so many of these but not many of them seem to match up to my car.

I have issues with the dash lights and some wires still hanging loose and need a decent wiring diag as a starting point.

 

SP

[Clive]

All the cars are mainly the same, so yes. 

Just be aware of the obvious stuff and differences (eg heated rear window!)

The colours are pretty simple and helpful. And indeed the diagram above is a good one to use from that point of view.

[NonMember]

There's also the dynamo vs. alternator, lack of hazard lights, single speed wipers and other stuff. So no, I don't agree with Clive; that diagram will cause confusion if you have a Mk3 Spitfire instead of a Mk3 GT6. The one in the proper WSM is correct, albeit not in colour.

[Clive]

Apols. Somehow I thought it was a mkIV spit....

(mind you my brain is a bit frazzled today. On a training course, lots of stuff being thrown at us very quickly)

[AidanT]

5 hours ago, Badwolf said:

Yes, I read about moving the grommet etc over and making a larger hole. Just wondering about the best way of adding anything extra like an additional power feed to the cockpit without making a total rat's nest of connections, but it looks like its not too bad.  As usual, probably over thinking the problems so nothing nasty happens when I set to with the cutters and hacksaw.

I used a thick solid copper wire to join the contacts. Once you add connectors there really is no access to enable s short as the connections are close enough so the insulated connectors covered the whole of the copper

 

Aidan 

[Badwolf]

Maybe a silly question, but does it matter which way the current flows through the fuse box to make sure that the leds work when needed. There does not appear to be any components in the fuse box apart from wire and the leds, so does the current have to travel  in a particu!ar direction. There are no input/output markings on the back of the box.

[NonMember]

LEDs are polarity sensitive so I'd expect it to be important which way round you wire it. (I'd also hope there's some resistors with the LEDs or they won't indicate the fuse failure for very long)

You can easily test. Connect a spare battery (even a PP3 9V one will do for this) to the two ends of a fuse position - take the fuse out first!!! - and see which way round the LED lights.

[Badwolf]

I took the gubbins out and without poking about too much had a bit of a look. Couldn't actually see any other electronics which did surprise me. I know that leds are generally like a one way valve so it also surprised me that the terminals are not marked for polarity but my knowledge of electronics, like car mechanics is limited!

UPDATE

yes there are discrete components on the back of the led pcb but too small to identify and connecting wires are very short!!

[Anglefire]

On 28/05/2019 at 09:47, Badwolf said:

Ok, thanks. I'm looking at the 90 degree female lucar connectors either crimp or solder (preferred),to give a little more space behind the 'glove box'. Also thinking of adding a cigarette lighter connector inside the 'glove box' to power phone, tablet etc. Probably off a perm live link. Did you use piggy back connectors for anything or just one single per connector blade?

I prefer to crimp and not solder as solder can cause issues - I can't think what they are off hand - its too early!

[Clive]

Soldered wire is hard, and with vibration can fracture. Which is why a QUALITY crimped connection is preferable (in industry you will be sacked for soldered connections in such an environment)

Back to fuses. What I don't understand with our cars is why the 3? main brown wires off the solenoid are not fused to protect everything. The one to the "purple" group already is, but why not the other 2 that feed the headlight switch (it has a fuse AFTER the switch, but doesn't protect the main/dipped lamps, does all others) and the ignition switch feed (again there is  a single fuse after the switch, but only protects the "green" group)

I reckon using a 8 way fusebox you could provide basic protection on these brown wires with 15-30A fuses (fuses "blow"at double their rated current) plus still fuse at the existing points. Plus a couple of spares for extras.... (relayed headlights, electric fan, that sort of thing) A fag lighter running a charger can safely be added to almost any circuit, current draw is low. If used as a fag lighter best to give it a new supply.