Classic cars forum & vehicle restoration.

VolvoFan · Joined: 14 Oct 2016 Posts: 11

I have a 1951 Sunbeam-Talbot 90 Mk2 and this is fitted with a Hillman Hunter Gearbox with J-type overdrive. There is an after-market reverse lamp fitted but it will only light when the ignition is "on" with reverse gear selected and the side lights are switched on.

How do I re-wire this so that the reverse lamp will light without the need to switch on the side-lights?

Can anyone draw a wiring diagram to support their explanation, as electrics are not my forte?!

Thanks for any good advice.[/i]

47Jag · Posted: Sun Nov 27, 2016 11:15 pm Post subject:

Hi,

If you look under the bonnet, try to see if you can find the fusebox. I'm not sure if by 1951 there were separate fuse boxes as oppose to being part of the voltage regulator. In either case look for the A2 terminal with a Brown/white (i think) wire This is the 'live all the time fused' terminal. Run a wire from there to the gearbox switch.

Art

Penman · Joined: 23 Nov 2007 Posts: 4755 Location: Swindon, Wilts.

Hi
I don't understand the wiring description in the original question.
They ar already off a permanent live circuit because they work with the side lights on (These have to be off the permanent fuse otherwise they couldn't be used when parked)
But they are also wired from the ignition on fuse.
Actually I think that that is the only fuse they should be on, as you can only reverse with the engine running
_________________
Bristols should always come in pairs.

Any 2 from:-
Straight 6
V8 V10

47Jag · Posted: Sun Nov 27, 2016 11:59 pm Post subject:

Penman,

It wasn't general Lucas electrical practice to have side or headlamps (same switch) through a fuse. I think the idea of taking the feed off the side lamp circuit was the logic that the they would only be required after dark.

Art

VolvoFan · Joined: 14 Oct 2016 Posts: 11

Thanks for your input. I'm inclined to agree with Art in that the view was that the reverse light was only needed in the dark!

I would think that the gearbox reverse switch is already wired from the A2 terminal; it is from that switch to the reverse lamp that I'm uncertain of and how the feed from the side light circuit fits in with this. I don't need to run the engine to operate the reverse lamp: just engaging reverse gear and switching on the side lights will make it light up, with the ignition OFF.

I must get underneath the car to check the wiring to see what's what. But first I'm waiting for some warmer weather to start crawling about in tight spaces!

VolvoFan · Joined: 14 Oct 2016 Posts: 11

Thanks for your input. I'm inclined to agree with Art in that the view was that the reverse light was only needed in the dark!

I would think that the gearbox reverse switch is already wired from the A2 terminal; it is from that switch to the reverse lamp that I'm uncertain of and how the feed from the side light circuit fits in with this. I don't need to run the engine to operate the reverse lamp: just engaging reverse gear and switching on the side lights will make it light up, with the ignition OFF.

I must get underneath the car to check the wiring to see what's what. But first I'm waiting for some warmer weather to start crawling about in tight spaces!

Penman · Joined: 23 Nov 2007 Posts: 4755 Location: Swindon, Wilts.

Hi
That might be how they used to wire them, but, having them on in daylight is a very useful warning device, particularly back in the day when I was instructing.

It doesn't mean you shouldn't be looking and waiting for traffic from behind but it does draw their attention to your intentions.
_________________
Bristols should always come in pairs.

Any 2 from:-
Straight 6
V8 V10

Bitumen Boy · Posted: Mon Nov 28, 2016 8:40 pm Post subject:

47Jag · Posted: Mon Nov 28, 2016 9:27 pm Post subject:

No, no, you have misunderstood me. I was merely pointing out what the result of feeding from the sidelight circuit was. I agree with Penman & BB that it is better for modern conditions to have the reverse lights live all the time.

As I understand what you have described, the reverse lamps are currently fed from the side lamps. I don't know your car so I don't know where the connection into the side lamps would be. If you can access the reverse switch and check the colour of the wire. If it's RED it will be a side/tail lamp circuit. If you decide to go the 'live all the time' route you can disconnect the current reverse switch feed and tape it up securely and run a new wire from A2. Best practice would be find out where it originates and disconnect it there.

Art

VolvoFan · Joined: 14 Oct 2016 Posts: 11

Thanks, Art. Sounds logical to me.

alastairq · Joined: 14 Oct 2016 Posts: 1950 Location: East Yorkshire

The reversing light wasn't one required by law. (However, I believe, if fitted, must work?)
Therefore, no specific bulb wattage stated.

There is,however, a legal requirement to not show a white light to the rear at night,etc.

So, a reversing light which stays lit whilst going to go forwards is a no no!

As a sometime competitor in classic reliability trials, regulations require a car to be fitted with'a reverse light.'
This can usefully be a spotlight if one is handy?
(Needed, as long distance trials often have Observed Sections run in the dark. If one fails, one probably will have to reverse down.)

Many vehicles have work lights on the rear too.

All quite 'legitimate, subject to the white light rule as above.

So, if rearward visibility is needed, why not fit a spotlight, made switcheable?

Bitumen Boy · Posted: Tue Nov 29, 2016 11:29 am Post subject:

Penguin45 · Joined: 28 Jul 2014 Posts: 381 Location: Padiham

Reversing lamps are not part of the MoT test.

P45.
_________________
'67 Wolseley MkI 18/85, '70 Austin MkII 1800 The Landcrab Forum.

VolvoFan · Joined: 14 Oct 2016 Posts: 11

I thought I read somewhere that the max permitted wattage for a reverse lamp was 21W.

Phil - Nottingham · Joined: 01 Jan 2008 Posts: 1252 Location: Nottingham

It is still 21w max per light and they must not be light going forward and always has been - a simple job to trace the side-lamp fed wire to whence it came and divert and/or extend to an ignition fed circuit via a line fuse near the regulator or ignition switch
_________________
Rover P2
Rover P4
Rover P5 & P5B
Land Rover S2 & S3
Morris Mini Traveller Mk2