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MG MGA - flash/dip switch relay Update

Sorry to start this thread again but although I have tried a few times, I just couldn't get it to re-activate from the archive.

This is a copy of my original post from earlier this year.

9th January 2012

I have been having some problems with the foot dip switch recently and most times when I press the dip switch it just switches the lights off!

So today I finally decided it was time to fit the special combined dip switch/flasher relay that Barney describes on his MGA Guru website which replaces the dip switch with a simple flasher switch on the dashboard. It is a Volkswagen relay from the original Beetle I believe but is still available new from them.
It has been on my workbench for quite some time now and the dip problem has just jumped it to the top of my To-Do list.

It works really well and it was pretty easy to fit too.

I mounted the relay on the dashboard-stay quite close to the steering column for ease of access.
Removing the dip switch and its bracket was the most awkward job as its not so easy to squeeze my XL torso between the seat and the steering wheel.

I was pleased to find that the dip switch wiring loom (3 wires) was plenty long enough to connect straight onto the new relay.
This left 2 more connections,one to earth through the new flasher switch on the dash and the other to the main 12 volt supply through a new in-line fuse.

My car has a Moto-Lita steering wheel fitted and its smaller diameter allowed me to fit the new switch into the hole usually filled by the indicator light.
This has made it within easy finger range of the steering wheel.
I moved the indicator light switch into the place usually taken by the instrument dimmer rheostat behind the steering wheel which is great as I can now actually see it working. (In its original place the Moto-Lita wheel rim completely obscured the lamp.)

I have moved the rheostat to a new position under the dashboard on a new bracket fixed to the dashboard stay. It is in easy reach to adjust when driving but to be honest, I havent adjusted it since I first set it 5 years ago.

So now I can flash the headlights when the lights are switched off which is something that I have always needed for my MGA.

Then, when the headlights are switched on, I can use the same switch to flip between dipped beams and main beams at the touch of a finger.

It is certainly much easier for me to operate than the foot switch as my size 12s tend to get jammed down behind the clutch pedal.
It also gives more space to rest my left foot whilst driving.

If you use the original full size steering wheel you may have to drill a new hole for the flasher switch as they did back in the 60s.

Fortunately I didnt have to drill any extra holes in my dash to do the conversion and so it can be reversed back to original state very easily.

I took my own advice and connected a low output power supply to make sure everything worked safely before connecting the battery. (Learnt the hard way a few years ago!)

So thanks Barney, a great modification.

30th January 2012


Well I have finally got my digital camera back from my son who borrowed it just before Christmas and inside all the pics I took of this relay.

Back to the new relay,I forgot to mention that to move the indicator lamp into the position normally taken by the rheostat, I had to extend the two wires about 6 inches to make them reach, on my car the lamp has spade connectors so it is pretty easy to make up these extensions
Similarly I had to extend the wires to the dimmer rheostat to make them reach its new position on the dashboard bracket near the steering column.

When I tested the new switch I noticed that it was only flashing the low beams when I used it as a flash to pass switch, but with the headlights switched on, it worked perfectly as a dip switch.
So I decided that either my cars original headlight loom was at fault or more likely, it was down to my suspect wiring skills.

In the event, both were correct but on checking the schematic on the side of the relay I realised that it has a slightly different circuit to that in the relay mentioned on Barney's Mga Guru website.

On my relay you have to connect the high-beam wires (blue-white) to terminal 56a on the relay and the low-beam wire to terminal 56b which is exactly the reverse of Barney,s relay.

So once I switched the wires around everything worked perfectly and now I can flash the high beams, which is exactly as I wanted.

The dip switch operates exactly as the original switch and so if you turn off the lights when the high beams are on, then they will still be on high beams when you switch them back on.

As I mentioned earlier, I wanted to try a temporary fit of the relay to make sure it worked as expected before making everything permanent. This is why I used existing holes for the switch and moved things around a little to make it fit.

Also I didn

Colyn Firth

I like it. I too haven't changed the rheostat - you sure as heck wouldn't dim the dim dash lights anyway; in fact i have a bridging wire across the terminals in case anyone else fiddles with the switch. It makes sense to move the indicator warning light to somewhere more visible so that you don't have to look too far down/away from forward looking to see the light is working.
C Manley

I only seem to be able to upload one pic at a time on this forum. Is there an easier way to upload multiple pictures?


This is the re routed wiring loom

Colyn Firth

The relay fitted to the dashboard brace and the rheostat on its new bracket.

Colyn Firth

A better picture of the new rheostat bracket

Colyn Firth

The clever little connectors that I have used as a temporary fix,

Colyn Firth

The new relay showing its wiring diagram

Colyn Firth

My own,very basic, wiring diagram

Colyn Firth

Updated web page with photos for this installation is here:

The special relay is available for Under $20-USD if you shop around.

This is a electrically latching relay, so when all power is removed it should unlatch and revert to low beams next time the lights are switched on. If it stays latched in the high beam condition when lights are switched off, then there may be some small parasitic power drain that could eventually run the battery down when parked (maybe 30 days). This would be similar to a modern electronic radio that requires a very small current to retain memory when switched off.
Barney Gaylord

This thread was discussed on 31/01/2012

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This thread is from the archive. The Live MG MGA BBS is active now.