fusebox/ lighting circuit

[Greenstag]

I wonder if anyone would mind clarifying the wiring connections at the rear of their fuse box (that’s if you can see it). I’m currently investigating some short circuits in parts of the lighting circuit and came across some evidence of heat in this area. I couldn’t get a decent picture so I’ve tried to describe the relevant terminal below



Terminals 5 & 6 both have red wires coming from them and serve the parking light circuit

Terminals 7 & 8 serve the sidelight circuit 7 has a red and black wire 8 has a red wire but this is coming straight from the neighbouring terminal 6

Was this normal or has a previous owner possibly done it because there’s been a problem with one circuit. There is no independent wiring coming from no.8 at the moment

What is the difference between parking lights and sidelights in this context. Should they be separate circuits

I can’t find a circuit diagram that actually shows the fuse box.



Many thanks



David aka Confused Greenstag

[brian0443]

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David

Your red wiring loopis correct if you have a Mk2 after LD20001 but the fuse numbering you have given would suggest that things have been done upside down and if you have two reds on the 5/6 fuse someone has replaced a wire.

You should have:

Fuse connector 5 takes a redlive lead direct from the master light switch when it is on.

Fuse connector 6 should have a red/orange feed to the RH side and tail lamps.(You lissted this also as red. Check the colour again and hopefully you will find an orange stripe.

Fuse connector 7 is fed by a looped red wire from 5

Fuse connector 8 has red/black running off to serve the LH side and tail lamps, number plate, dash illumination etc.

If you do have two reds on 5/6 you need to ensure that fuse 7/8 is drawing its power from the unfused side of 5/6. Easiest check is to remove fuse 5/6 and see if 7/8 still lights its circuit. If it does you are OK.

In the 60smany vehicles had a lighting arrangement which allowed side lights on one side only to be left illuminated at night...parking lights. I don't know whether the Mk1 had this but its not a Mk 2 feature. For our Mk2 wiring diagrams parking lights simply means drivers side tail and front side light.

I have somewhere a listing that I did when I was doing my own fuse box and if I find it I will send it to you. Meanwhile if you look at the wiring diagrams, find 18 and 19, and work back you will see the fuse shown as two little circles joined by an elongated X. The fuse contact numbers are shown on this, though they are very small. You can do the same for the rest of the fuses and check them against what you have.

Send me a PM or an e-mail if you need more help, or a copy of the wiring diagram.

Brian

[stagstr]

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Hi David,

I've just shone a torch into the fuse box area and I can't see a thing! However, I do know that I have used the fuse box many times to take feeds for things like alarms, radio, CB, immobiliser etc so it's highly likely that any previous owner of your car has done the same. The big clue as to whether anything is original or not is to look at the type of blade connector. I doubt you could buy (at Halfords etc) the same type of blade with the very angular clear insulation that Triumph used. So you should be able to work out what is original and what's not. The number of connectors on a given termminal is a clue also.

The difference between parking lights or side/tail? I think this is a left-over from the USA market whereby it looks from the USA wiring diagrams that you could put the drivers side lights on whilst parked - LHS in the US. That is why the drivers side has a separate fuse from the rest of the lights - passenger side, number plate, instrument etc. I don't think that facility was used in the UK, but I guess the fuse box and cover were common to all markets, so it is labelled that way.

You need to check your wiring diagrams - page 86.00.05 in the ROM or page 151 in Haynes, assuming you have a MK2 heater, RHD car, and from your photo it looks like you do. You will see that the fuses in this area are shown, but, as you say, not in a diagram of the fuse box in its entirety, but in the relevant wiring section.

On the basis that I cannot check my wiring because I can't see it, but also with the confidence that the wiring diagram is not wrong in this area, then having red on both 5 & 6 is wrong.

5 should have two red wires, one from the Master Light Switch and one going to 7.

6 shouldhave RO whichI assume is red/orange, there being no key shown for "O", going to the RH side lights ("parking lights").

7 should have one redlinking backto 5.

8 is red/black and two wires emerge, one going to the LH lights, number plate etcand one to the instrument panel rheostat.

Finally, are you sure you have the fuse box cover on the right way round?

Finally, finally, in the UK, there seems to be no earthly reason why all the lights which are put on by turning the Master Light Switch to Sidelights should not go through one upratedfuse betwen terminals 7 & 8.Your previous owner may have done this in order to free up the fuse between terminals 5 & 6 for some other use.

Let me know if this has helped or I can clarify any of my ramblings!

all the best

Ray

[Greenstag]

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Brian /Ray

Many thanks to both of youfor your comprehensive and useful replies. You both seem to be erring towards the same prognosis and yes I too would guess that someone in the past hashad a tamper with the wiring. Thanks for the sidelight/parking light info.

Yes Brian I would appreciate a copy of your diagram I'll send you an email soon

Sorry should have confirmed it is a 1976 MkII but good detective work in spotting that it is.

Armed with all that info I will now be spending the weekend on my head in the passenger well



Thanks again

David