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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 Midget and Sprite Technical - Now It's My Turn

Well, now it's my turn to deal with the electrical gremlins.

I was out today and it was lovely sunny weather, I have the top down and just having a grand time. I'm stopped for a traffic light and some guy behind gets out of his car and runs up to me and says, "Don't think you know this, but you have no brake lights." Oh, great. Just what I have always wanted to hear.

Get home and cut a block of wood to hold the pedal down and both my test lights don't work. Bulbs are burned out. What are the odds? Worked last time. Oh a quick piece of advice, don't ever inadvertently hold a spring and run electrical current through it! It gets hot real fast!!!!!

The rear running lights both work so there is a good socket ground there. Both of the filaments in the bulb are good too. Hey, check the obvious first, right?

So, once I get the test light sorted I'll begin with the fuses (probably not them), brake light switch, wiring and connectors unless anyone has some suggestions to offer.

It's a Mk IV with the 1500 engine by the way.

Cheers,
Clare
Clare Ravenwood

My money is on the switch Clare, unless it's the dreaded corroded bullet connectors in the boot. Hope it's one or the other cos they're easy fixes.

Cheers.
Greybeard

100% agree with Greybeard. It will be the brake light switch.

Very quick check is to connect the two spade connectors that plug into the switch together. Then with ignition on, walk round and see if the lights are on. If they are, then it is a faulty switch.

Be aware though that the replacement switches available are generally poor quality. Or at least they were recently. Maybe there is new better stuff circulating now.
GuyW

We have a company over here called Grangers. Big industrial supply outfit. I bought a momentary ON switch to replace mine.
J Bubela

The suspect items are the replacement hydraulic pressure switches rather than the contact switches that are I think used on the later cars, or is it just on the export cars.

The Hydraulic operated ones do sometimes benefit from bleeding. Slacken the switch from the 4-way connector a little and press the brake pedal lightly to expel any air bubble that might have collected there. It can revive the switch operation.
GuyW

I would imagine that Clare's 1500 would have the mechanical switch on the pedal box. North American spec cars had dual-circuit brakes from 1968, which is why the hydraulic switch was done away with, AFAIK.
Dave O'Neill 2

Have not delved into the problem yet but I have a mechanical switch on my car.

Have to lift the pedal box up to change it.

Fortunately, I happen to have a spare switch kicking around. Got it ages ago when a repair garage closed down and I bid on box of assorted light bulbs in boxes and some odds and sods were in it.

A number of the odd bulbs and bits were in BL boxes, among them a switch so it should be of good quality.

Clare
Clare Ravenwood

Put a jumper lead across the switch and turned on the ignition. Lights come on so the switch is pooched. Think I can find my spare one? (lol)

Clare
Clare Ravenwood

You'll find it right after you buy a new one ;-)
Martin

I just had an interesting conversation with a mate over a pint. He has built up several kit cars and for brake light switches favours universal motorcycle rear switches. As they are required to work in wet, dirty conditions they tend to be robust and reliable.

All you need to do is find a convenient place to hook on the fixed end and I speculate the horizontal part of the 1500s throttle pedal might do nicely, with the other end going to the brake pedal of course.

Just a thought to pass on for anyone unable to find good quality switches....

Happy weekend All.
Greybeard

Seems l could fix one in place of my non existent brake pedal return springs then !
GuyW

I hadn't thought of that Guy. Hmm.....

Although I remember a Landrover with a short length of bungee cord for a throttle return!
Greybeard

Its just now warming up in canada so its most likely going to be condensation related

Im going with bullet connectors if not that, then id look at the grounds

If it is the brake switch that went bad...DONT USE the old lucas style unless you need reliability

Us an aftermarket inline brake switch... you simple cut the brake pipe and then the new switch ias just an advsnced compression fit into the pipes it has 2 wires that you wire nut or soilder into the electrical system
..its pressure activated instead of mechanical peddle activated

Its after market so try a good local parts/race shop

Or jegs.com / summitracing.com....will definatly have them.... around $10

But im going with bullets....its always the bullets in spring
1 Paper

I may be wrong on the plumbing i think you make a side extenstion off the brake pipe...not a pass thur... still pretty easy to do.

Here is a link to a switch and it even has its own harness...nice

http://m.ebay.com/itm/Summit-Racing-890002-Brake-Light-Switch-Fluid-Pressure-Actuation-20-amps-Steel-N-/191682554162?nav=SEARCH

Prop
1 Paper

Correct...inthe usa they are mechanical switches and are not very good

Or at least the 2 i had, the universial fluid pressure activation switches is a much more reliable part
1 Paper

Prop, it is a mechanical switch on my car. It is also about 40 years old as it looks to be the original to the car so that is not bad.

I jumped the switch leads with a test lead and the lights work just fine. The running lights work just fine so the grounds are good as are the brake circuit filaments in the bulb.

Tested the switch with a multimeter and it reads 0 all the time when pressing and releasing the button so it failed, as there is no internal connection.

My master cylinder is not set up to accept a pressure switch. I also figure the guys who designed the car know more than I do about engineering so I am not about to start cutting hydraulic lines and jury rig something that may or not work properly or cause further work/potential trouble spots. I am also alone so no way of bleeding the system out and the cost of getting all this stuff (vacuum bleeder, pressure switch and related parts, wiring etc) far exceeds the cost of a new part I am sure.

I have a spare here somewhere and it is about 20 years old so it is good original equipment quality as opposed to the junk today.

A few hours of work I will be back on the road again with minimal fuss.

Thank you for your suggestion though.

Clare
Clare Ravenwood

If your replacment part is 20 years old ...then you should be okay for another decade or 2

So your good

To bleed the clutch is easy and you dont need any special gear

Get about 6 feet of clear vinyal tubing inthe plumbing section at home depot (12 cents per foot or so less then a dollar) that will fit snuggle over the bleed vlave of the slave (may use a bread tie if the fit is to light) stick the other end into the master resivore,crack open the valve a small amount and then pump the peddle slowly and completly and watch the clear tubing for air bublea, once no air bubbles are seen, close the bleeder valve and becareful pulling the clear tube out of the bay because dripping brake fluid loves eatting paint and toss it into the trash... the tubing 1/2 melts in 3-5 days

Easy and works on brakes... but watch the proportioning check valve not sure how that works

Prop
1 Paper

Don't know if it helps but I use aquarium tube. Cheap,durable and effective.
Greybeard

Hmm what did I miss?

Clare has done the diagnostics now, it's a mechanical (In the pedal box switch) so there is no need for her to open the hydraulics

I fitted a later pedal box to mine a few years back so there is a mechanical switch stashed away in one of my little blue wall mounted bits boxes

If you need it I will hunt it out for you Clare

But the advice to use a motor bike switch is really good

Take the junk switch to your local bike spares shop, they should be able to help you out

I used to work in a bike shop and there is nothing in the world that will stump a bike chap when it comes to wangling a fix from available bits

if not, give me a day or three, I'm rebuilding my bike speedo/computer, the Sigma finally gave up its ghost
Bill sdgpM

Gray

Yes...thats it same stuff

Prop
1 Paper

This thread was discussed between 19/05/2017 and 24/05/2017

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