MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGA - electrical problem

Hello all,

My brake lights have stopped working on my 1960 Mark I for some reason and I wonder if anyone can suggest what might be the issue. I've checked the bulbs, wiring and fuses which are all good. I was next going to check the brake light switch (when I figure out where it is!) but then noticed the ignition light stays lit (but ever so faintly) when the car is running. This has happened before and a new regulator fixed it but I don't remember the brake lights not working that time as well.

Might I need the replace the regulator again?

Thanks in advance.

Jason
Jason Ogelman

The brake light switch is hydraulic and sits in the rigid pipework which runs vertically downwrds on the driver's side (uk) fairly close to the knuckle joint on the steering. It is very low down.
It is easy enough to test with a multimeter in-situ.
These switches have a history of failing, probably related to modern replacements sometimes being lower quality.
If you need to change it, it can be a real horror because it is so easy to tear the brake pipes out of the fitting. I think a possible cause of this is that if the car has been rebuilt the switch and socket may well have been assembled on a bench and overtight as a result ('...well we don't want it leaking fluid')
When mine failed I left it alone and ran the cabling through a pedal-mounted mechanical switch, which a fair few owners have done.
Graeme Williams

Jason,
If you have a standard set-up, its most likely to be the brake light pressure switch which sits on top of a four way brake pipe connection mounted on the chassis below the universal steering joint. It has two green wires that go to the brake lights so you can run a hot wire to test that the brake lights work, if they do its the switch. From memory I think you can just unscrew it and replace with a new one without having to bleed the brakes but I'm not sure memory is 100% correct. No doubt the guys will correct if wrong. There was some discussion about the quality of current replacement. Think it highly unlikely that the dim ignition light is connected to this problem.

Regards

Alan
AR Terry

Jason

As others say and can be a right pain to replace. Bit easier if you can elevate the car for access. When getting a replacement make sure it is specified for an MGA. It has a tapered thread.

Steve
Steve Gyles

Being that your in England see if you can find a Hella brand from an air cooled VW. They would be better than some far eastern copy as long as they have not switched production too.
gary starr

Today's after market brake switches seem to be of poor quality. I bought a switch from Ron Francis in the USA, which were advertised as being of the best quality. After 7 months in use, someone brought to my attention that my braked lights are not working. I pushed very hard on the pedal and the lights came on. Someone on this forum suggested the installation of a relay in the brake light circuit. This was done in no time, and now my brake lights work perfectly, even with slight normal pressure at the pedal.

Frank
F. Camilleri

Ignition lamp has nothing to do with the brake lights, different circuits, different problem. The pressure switch is on top of the frame on lower right side, in top of the 5-way fitting with brake pipes. Ignition switch on, short across the switch terminals with a coin. If the brake lights light up the wiring is good and the switch is bad.

After burning through 8 different switches in one year, I found a good one (and maybe three good ones). Ron Francis is one of the known failures. The one now in my car is up to 17 months and 50,000 miles still good. No need for a relay or separate mechanical switch, just buy a good switch (and of course avoid the known bad ones).

Jason, -- Assuming you will replace the brake switch, see if you can find he brand name and part number of the failed switch. I'm keeping the list of known good and bad switches. See here: http://mgaguru.com/mgtech/electric/et119a.htm
Barney Gaylord

Went on some VW sites and found that many of those guy's have the same problem mostly with Olympic brand switches. It was advised to only use Hella switches- here is a link with part numbers- http://www.rallylights.com/hl66228-stop-light-switch-2-prong-oem-p-n-113-945-515h.html
gary starr

VW is German car. Does the Hella switch fit the 1/8-NTP tapered pipe thread?
Barney Gaylord

Not 100% sure but I have heard in the past they fit. Link states it fits Rabbits from 75-84. They started building them here in the US for 1980 model year. For 17-18 bucks it sure would be worth checking out.
gary starr

On further review yes they are metric and will not fit. How ever they do list this one-
http://www.pacificcustoms.com/mm5/merchant.mvc?Screen=PROD&Store_Code=PC&Product_Code=cnc888&Category_Code=brake-light-switches
gary starr

Barney. I see in your link you noted quite some time ago, more than 2/3 years ago from memory, that an Intermotor switch purchased here in the U.K. was working well. I can update you - it's still working well!
Best
Bruce.
B Mayo

Before you go to the trouble of buying a new switch, just try removing the old one. I gave up when I could see it was going to end in disaster.
Everything said here confirms my view on new pressure switches, which is why I made up a simple bracket to hold a mechanical switch activated by the brake pedal down in the footwell.
Graeme Williams

I'm with you, Graeme. I've just finished a 5 year full restoration and the new brake switch failed after only 2 miles!
Since I've been reading here about the "quality" of these hydraulic switches, I installed a mechanical switch (un-wired) at the brake pedal prior to putting the body back on. Didn't know I'd need it so soon. Happily, two wires installed and all works now and I'll never go near that deep, dark corner of the chassis again - I hope!
I learned of this issue and many others here in these threads, so thanks to all of you.
And Merry Christmas all!!

John

JR Alexander

You guys don't reed the prior posts before posting? No need to muck around with extra switches, brackets relays, wires, increased complexity, more possible failure points. Just but a good pressure switch.
Barney Gaylord

THe reason I didnt stick with hydraulics was the fact that the switch was extremely tight in the socket. That, coupled with difficult access made me decide to change the system. I just couldn't hold the socket firmly enough to stop it turning. Maybe had I had a proper lift...
Graeme Williams

This thread was discussed between 21/12/2016 and 24/12/2016

MG MGA index

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