Headlight wiring driving me crazy!

[Prawnabie]

Hi all,

My first post here and I am hoping you can stop me going crazy trying to fix a something that may or may not me a problem!

I have a late Herald 13/60 that I have almost finished restoring and noticed today that when I flashed the main beam, all the sidelights came on too! I spent hours checking the wiring and switches etc and noticed it only happens when the master light switch in the dash is off and the column stalk is in the main beam position.

The flasher circuit portion of the switch is fed from a brown and the switch portion of the switch is fed from a brown/red wire. When you have the switch in the main beam position, it links the two halves of the switch together and the feed from the flasher side back feeds through the switch side and thus into the sidelight circuit.

Now I'm guessing you wouldn't drive around with the master light switch off and the column switch in the main beam position, but you can have them in this config and being able to "flash" your side/tail lights doesn't sound right to me?!?!

Any help would be gratefully received!

 

Thanks

Shaun

[Prawnabie]

Please see following crude diagram....

[NonMember]

On 01/10/2021 at 18:12, Prawnabie said:

when I flashed the main beam, all the sidelights came on too! I spent hours checking the wiring and switches etc and noticed it only happens when the master light switch in the dash is off and the column stalk is in the main beam position.

Perfectly normal. As shown in Prawnabie's diagram, the flash circuit powers the main beams, and when the stalk is in the main beam position is connects the main beams to the master light circuit, so the flash powers that, too.

[Prawnabie]

Thank you very much I shall plod on!

[Colin Lindsay]

1 hour ago, NonMember said:

Perfectly normal. As shown in Prawnabie's diagram, the flash circuit powers the main beams, and when the stalk is in the main beam position is connects the main beams to the master light circuit, so the flash powers that, too.

Surely the problem is that the sidelights and taillights come on, too? That shouldn't happen...

[NonMember]

2 hours ago, Colin Lindsay said:

Surely the problem is that the sidelights and taillights come on, too? That shouldn't happen...

Yes, it should, at least it always will if you operate the flash when the stalk is in the main beam position but the lights are off. As I said (and Prawnabie drew) it's what the circuit is designed to do. You may argue that the switch "should" disconnect the main beam from the master light circuit when connecting it to the permanent live feed... but they don't because that would have cost more (and probably made the switch really unreliable).

[A TR7 16V]

On 01/10/2021 at 18:12, Prawnabie said:

when I flashed the main beam, all the sidelights came on too! I spent hours checking the wiring and switches etc and noticed it only happens when the master light switch in the dash is off and the column stalk is in the main beam position.

I didn't think that mine did that, and I checked and they don't. I worked out that's because a PO connected the sides to the same first position output of the master light switch as the instruments, so the side lights come on at the first pull of the master switch, and only connect to the feed into the column switch when the master is all the way out.

That the side lights should always be on with the instrument lights seemed so right and logical to me, that I never questioned it. And as I've never ever wanted to drive with just the instruments lights on and can't imagine why I ever would. I have no intention of "correcting" it.

Graham

[NonMember]

10 hours ago, A TR7 16V said:

And as I've never ever wanted to drive with just the instruments lights on and can't imagine why I ever would.

That's not how the factory wired it. The original wiring has the connections on the master light switch the other way round, so you can drive with side-lights (or even main beam) but no instrument lights.

[Jeffds1360]

I just confirmed that I have exactly the same as Shaun (prawnable) on my 1971 13/60.

The only fuse on the car is on the main beam 'flash' feed and YES, the side lights feed off this when the stalk is in the main beam position.

My instrument lights only come on after second 'click' pull on the master switch.

Hope that clarifies it

[NonMember]

3 hours ago, Mathew said:

That's all mk4's and 1500's.

Yes, because Triumph changed the way the lights were done for Mk4. All Heralds and rountail Spitfire/GT6 had a three-position headlight stalk with side/main/dip positions, and a two stage master with off/lights/lights+gauges positions. Mk3 GT6, Mk4 Spitfire and Mk2 saloons all adopted the more modern off/side/head master switch and the two position main/dip stalk.

[A TR7 16V]

4 hours ago, NonMember said:

That's not how the factory wired it. The original wiring has the connections on the master light switch the other way round, so you can drive with side-lights (or even main beam) but no instrument lights.

Why?

I'm sure that will be contentious, but I really don't see the point of separating sides and interiors either way. And, from what's said about later Spitfires, it sounds like Triumph/BL agreed.

What I have, even if it's wrong from the originality perspective (but still reversible) makes sense except for the third, side lights only, position of the column switch which replicates the first position out on the master. And even while that third position is currently pointless, I can see how I might use it if I fitted front (or front and rear) fogs.

In that case I would power the sides (and instruments) and the mains and dips (optionally through the column switch) off the first and second positions of the master and the fogs off the second only. I'd want another warning light for them though - I so hate those twits (or spelt with a different vowel) who drive on rear fogs cos it was a bit misty earlier in the year.

Graham

[Colin Lindsay]

56 minutes ago, A TR7 16V said:

Why?

I'm sure that will be contentious, but I really don't see the point of separating sides and interiors either way.

If you've ever tried it, driving at night with no instruments gives a very good view of the road ahead with no glare from inside the car, and the instrument lights don't annoy your eyes when you're looking straight ahead and they're just hitting the edges of your receptors where they're more sensitive (the way you look at stars by looking to one side, not directly at them). Modern cars such as Saabs have a 'night' setting whereby the instrument lights extinguish just leaving you a portion of the speedo illuminated. 

[A TR7 16V]

6 hours ago, Colin Lindsay said:

If you've ever tried it, driving at night with no instruments gives a very good view of the road ahead with no glare from inside the car, and the instrument lights don't annoy your eyes when you're looking straight ahead and they're just hitting the edges of your receptors where they're more sensitive (the way you look at stars by looking to one side, not directly at them). Modern cars such as Saabs have a 'night' setting whereby the instrument lights extinguish just leaving you a portion of the speedo illuminated. 

Nope, never had that problem or the desire to avoid seeing the instruments. Indeed, I was taught to continually look down at the instruments every few 10s of seconds or so while driving. Having them off while driving in the dark is dangerous madness in my book.

Turning them down a bit, despite the cost of the rheostat, might make some sense. But I've had enough cars with adjustable instrument lighting and never set that anywhere but full. The 73 Doly Sprint don't even have that, just on with the sides. Mind you I don't know if the early 1850 it's based on had such adjustment: that being a proper production car, not one where they made exactly enough (to within less than 100 in 73) to get and keep the FIA Group 1 homologation they needed for the British Saloon Car Championship becoming a Group 1a series from 1974. The "a" in that is another interesting subject.