I've made a mistake somewhere

[Colin Lindsay]

It's possible someone has tried to uprate the circuit by adding a relay, either to protect the switch or the loom itself - have after market headlamps been fitted? Some switches can suffer from burning over a period of time, so a relay will keep the current low at the switch whilst allowing higher at the headlamps; however the majority of relays in the lighting system are in the engine bay with additional or higher rated cables running to the bulbs. I haven't seen one behind the dash as it usually means stringing too much additional cabling.

[Josef]

Well as you think you have a new loom which has then been modified, I wouldn’t cut anything without being very very sure you need to. I’d do as Colin suggested and try to wire the car up as standard, ignoring anything that is a customisation, and only then figure out which of the mods you wish to retain. Can’t say if your relay does anything useful or not without looking at the wiring myself (the purpose of adding one in classic car wiring is most usually so you are not running high currents through dashboard switches.)

[NonMember]

9 minutes ago, Josef said:

the purpose of adding one in classic car wiring is most usually so you are not running high currents through dashboard switches.

Not quite. The main purpose on Triumphs is to make sure you're not running high currents through the column switch, because that's the one that's under-spec and prone to melting. Having a relay between the master and the column, as was stated, won't help that. Also, wiring the top "contact" pin of the relay to the top "coil" pin, and thus the switch, also won't help at all, because you're still feeding all the current through the switch (and yes, I have seen that done, with the relay behind the dash). Like I said, and as Colin suggests too, you're much better off getting it working without the relay, as the factory designed it, and then thinking about how to wire a relay in correctly. At the moment, based on the description, that relay is a possible cause of the problem and of no benefit, so eliminate it for now. Make sure the wires are as per the original wiring diagram:

- a brown wire from battery (via control box) to the master (dash) switch

- a brown/red wire from the master switch to the column switch

- a blue/red wire from column switch to dip beams

- a blue/white wire from column switch to main beams

Nothing else in the circuit (apart from bullet connectors).

[Neil Clark]

OK.  I've no mods now, I've stripped those all out and I'm trying to get to only having the essentials.  The relay and its wiring is definitely additional, NOT part of the new loom that was fitted a the last restoration about 2015.  I'll do as suggested tomorrow and let you know.  It may take a little while due to the kaleidoscope of wiring colours.

I keep going over the wiring diagram and what I can't get out of my head is that the headlights were working fine until I connected the side and indicator light looms.  Then as soon as I switched them all on the 35A fuse on the bulkhead audibly popped and only the side and indicators would function plus the blue main beam and flasher indicator operated by the column stalk.  All 3 fuses, the two on the bulkhead and the line fuse are fine now.  Enough for tonight!

[Neil Clark]

Before I do anything can you all help me to sanity check some points please?  Car is Mk1 but I cannot see a control box in any obviously accessible position under the bonnet or under the dash.  

It has an alternator.  

It is negative earthed.  

It has the early fuse box on the inside of the firewall holding 2 35A fuses and also has a 35A in line fuse.  

It starts and runs wonderfully well, temp gauge, rev counter and fuel gauge work fine.  Speedo is still the mechanical type.

Instrument lighting not yet working.

 

[DanMi]

the control box would be in the middle of the bulkhead under the bonnet beside the washer bottle, but if an alternator has been fitted it is not required so may well have been removed. Conversion to -ve earth is very straight forward and needed for an alternator conversion. Fusebox sounds correct for an early car. The original wiring is very basic you may well see some brown wires connected together where it would be and 3 captive nuts in the bulkhead.

[NonMember]

As Dan said, the control box was probably removed for the alternator conversion. It's likely, as it's had a new loom, that the loom was updated at the time rather than connecting brown/yellow to brown wires where the control box used to be. Instead, there will be a point where a lot of brown wires are joined together, quite likely on the starter solenoid. So there should be a medium-heavy brown wire going from there to the master light switch.

It would be useful to know which fuse it was that popped - what colour wires does it connect?

[Neil Clark]

Thanks.  No control box.  Here are photos of the fuse box area.  It was the lower of the two fuses that blew.  The brown wire that goes to the line fuse emerges from the loom and on the other side of the fuse it is red. It runs across behind the instruments to the relay at the steering column mentioned yesterday.

As for the little square black box seen on the fuse box photo it is unlabelled, has a loose earth wire and makes no logical sense!

There is also a small green lamp on the fascia.  I can't see what it is for and the wiring doesn't seem original but will photograph and try to trace.

[Neil Clark]

Beter photo of bulkhead fuses.  The lower one blew.

[Neil Clark]

Extra Green Light on Dashboard - I wonder if this has anything to do with the electrical fuel shut off valve that was fitted?  Green wire goes to white wires on rear of ignition switch and went through bulkhead to the shut off valve.  It doesn't seem to do anything else.

[DanMi]

there is no extra green light on the dash, that is the indicator repeater and is standard

[DanMi]

and I hope you have the battery disconnected as it is very easy to short the wiring with the dash out 

[Adrian Cooper]

It looks like the PO has used the indicator repeater that DanMi mentions as a warning light for the fuel shut off. Certainly it should not be wired into the ignition feed.

[DanMi]

My personal opinion would be to go back to stage 1 and put everything back to how it left the factory as trying to diagnose faults in someone else's improvised wiring will be a nightmare. 

[Adrian Cooper]

Can you get a picture of the back of the master light pull switch? You mention that the instrument lights don't work and they should be fed from that switch. It might be that some of the wires have been pulled off or put on the wrong terminals.

[Colin Lindsay]

The little black box is probably an aftermarket voltage regulator, the black cable should be earthed. You can see the old one in the same photo, marked 'top'. 

[DanMi]

the flasher relay should be attached to the bulkhead through the hole to the left of the fusebox with a small screw through the centre of the base (won't sort the main issue though) and the black box does look like a solid state voltage regulator and the wiring is correct for that. I would do everything in my power to get rid of the blue scotchbloc connectors

[Neil Clark]

Definitely got the battery disconnected!  The green light on the dash doesn't do anything when the flashers are working, which they do, so I imagine it is as Adrian says so I'll remove the connection to the ignition switch for now.  Yes I'll get that photo of the light switch later Adrian. 

The flasher unit was loose as you see when I took the glove box out.  It works fine and I intend to re-attach it once the current issues are solved.

Can I use the old voltage regulator with an alternator?

I  hate the scotchbloc connectors.  I used them once on a  kit car and threw them away after a month.  But I want to get the headlights etc working first then tidy up the connections.  I do hope that in the end I won't have to re-wire!

[DanMi]

the lower fuse (which blew) is for the sidelights only. It should have red wires on one side (OK) and a red/green on the other side (can't see) which comes from the main light switch. The instrument light are the red/white wires which seem to attach to some red wires via a blue scotchbloc so you would need to look at where they go to get the instrument lights working. To be honest that wiring is a mess. The inline fuse is for the main beam flash (pull stalk)and should have a brown wire going in and a brown/black out to the column light switch has the red been added or is it in the loom? is the brown black still there if a new wire has been run could that indicate a previous issue with the loom

[DanMi]

the old voltage regulator will be fine with a dynamo but if the fuel/temp gauge work then the new one is likely a modern solid state which will be more accurate and it was probably replaced as the old one wasn't working so just replace the earth

[DanMi]

The light green/purple wire on the flasher should go to the green indicator repeater on the dash

[chrishawley]

It’s a long, looonngg, time since I owned a MkI so please treat any comments below as ‘thoughts’ rather than opinions.

 

For sure, the green light in the dash is (meant to be) the direction indicator warning light. It should pick up its feed from the third terminal of the flasher unit (the wire colour of which is unspecified on the wiring diagram). But PO has made it a common connection to the whites on the back of the ignition switch. But does what is now an ignition-switched twelve volt feed terminate to earth at the bulb or does it have a forward feed to something? For example; if PO has done an alternator conversion has he used this as the alternator charge light?

 

I’m a bit bamboozled by the modern relay. It’s a switchover relay with terminals 87 and 87a. As far as I can see from the photo it only has three wires going to it. For an SOR to function it would have five connections usually. Or could just have four if it were just being used as a make-break relay. But if only three I don’t see what it can be doing other than just being a passive conductor of current. If abused, it could well be faulty by now.

 

There would be sooo much to be said for removing that relay. But an added complication is then that the relay currently has purple wires connected to it. But AFAIK there were no purple wires on these looms other than PY to the horns. So that leaves a question about what has been modded. (Although the captive wires on the column switches often had colours that did not correspond to the colours of the wire to which there were connected).

 

How about the fuse box? On the bottom fuse I can see two red wires which would be the feed out to front and rear side lights. But I can’t see anything going in on the other side of the fuse, in particular an RedGreen coming from the master light switch. Is it floating free somewhere?

 

Lastly, as already mentioned, the voltage stabiliser. Some electronic VSs will burn out if not earthed. For the time being this could be removed just to exclude one more factor. Simply connect the two green cables to the green/light green one to bypass it. The effect will be that fuel can temp gauges will tend to read high but a new one can be popped in at any stage when the more major problems are sorted.

 

But, like I say, ‘thoughts, not opinions.

[DanMi]

I would also carefully check the loom for signs of burnt out wires as not much is fused on these cars and in a crash a short circuit is fairly likely

[NonMember]

Oh dear.

As others have said, that wiring is a mess. It looks like some PO has taken it upon themselves to completely reinvent how it all works, and got it hopelessly wrong. If it were my car, I'd be very tempted to take the whole lot out and start again.

The black box is certainly wired in as a voltage stabiliser for the fuel and temp gauges. The green wires it's connected to should go to the metal can stabiliser to the left of the fuse box in your first photo. New ones of those are available, though not of the highest quality.

[Neil Clark]

I think, given all the above, that a new loom from the bulkhead into the cabin for the dash and controls makes sense.  Yesterday after one attempt to check if I had the new light switch connection correct I looked up to see smoke rising from around the ignition switch.  There are so many dodgy connections which I can't get a camera angle onto to show you.  Even if, stationary in my garden I can get it to work, I'm now extremely concerned about what would happen if I drive it and things vibrate and short out.  The original crash the PO had was due to the disaster of an accelerator rod linkage welded to the original to operate the Weber carb, which rested (yes really) on the exhaust manifold, stuck, and led to the accident.  I suspect that the dash wiring loom mods represent the same approach of botch botch and hope.

I'll keep poking about to try and learn what I can and photograph what I can but I'll see what I can do to buy a loom for the dash and switches that I can connect (with bullets).  I can leave the branch to the rear of the car "as is" 

Any suggestions for a supplier of a part loom?