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MG Midget and Sprite Technical - No Brake lights

My 79 midget has no brake lights, I replaced the brake light switch, still nothing but the leads from the brake light switch get hot to the touch. Can you give me an idea where to look? need help very frustrated here.
ws Semko

use a meter or a continuity tester or even just a test bulb with 2 wires attached, to test the circuit in different places to localise the fault. Do you have a shop manual with a wiring diagram in it?
David Smith

Make me think if the lights don't work and the wire gets hot to the touch that you have a short to ground before the brake lights.
David Billington

WS Semko.

What David and David said. But this might help.

If you open the boot (trunk) and look in the right corner you'll find a connector block with three green wires with purple stripes coming out of it. Looks like the photo, but in my car the wires have some yellow paint overspray on them. Disregard the connector block with red wires - they're for the license plate lights.

Here's some tests you can do.

1. Open the bonnet (hood) and disconnect the LT wire to the coil. This is important. You need the ignition on for the testsand disconnecting the coil will save it from burning out.

2. Identify the Green/Purple wire going to the right side stop light. This is obvious. Carefully pull out the bullet connector from the block. If the left side stop light now works the problem is between the connector block and the right side light.

3. If not, reconnect it and pull either of the other two Green/purple wires from the block. One comes from the switch and the other goes to the left stop light. It isn't obvious which one goes where because they both disappear into the loom binding. If the right stop light works but not the left the problem is between the connector block and the left stop light. If neither work and the wiring still gets hot at the switch the problem is between the switch and the connector block. Once you know where it is the simplest solution is "cut and shut" the bad wire using crimp connectors and some new wire.

4. It is possible for the problem to be internal to the connector block. When I was doing these tests on my car I found the bullet connectors to be corroded so I cleaned them up even though they worked okay. It might be a good idea to start with de-corroding the bullets.

5. Don't forget to reconnect the coil LT wire or your car won't start. It's easy to forget this - don't ask me how I know haha!

I hope this helps. Good luck.


Greybeard

X3... in fact id disconnect the battery when not in use... it really sounds like a double ground ... a shafed wire somewhere

i like greybeards approach for finding the fault

prop
prop

Hi,

Firstly have you got the correct 17.5/35amp fus in the ignition live circuit?


If the output to the brake lamps was shorted to ground, it ought to be blowing that fuse?


A favourite fault on midgets is wiring to the reverse light switch chaffing, which usually shares the same fuse.


Is the green wire "hot" even when not connected to the stop lamp switch?

Try jumping in a temp fused live, off the battery say, into the green/purple at the switch and see if the stop lamps work ok. Use a small fuse, 5amp or so, if this blows you deffo have a proplem in the brake light circuit.

If they work ok, look elsehere, it may be asymptom, not a cause!
SR Smith 1

Exactly Steve. It seems to point to a high-resistance fault more than an earth fault. I'm just guessing that the three-way connector block is a likely culprit.

I got rid of several of those in my headlight wiring because of poor connection.

I suppose it could be a sort of partial earth (again high resistance), but I don't think I've seen that more than once.

I like your idea of the temp, fused supply.
Greybeard

Hi guys,


Apologies for the awful spelling and typing in that post, I was in a hurry!


The wandering fused lead is a useful tool when fault finding, I use it a lot.


If the green wire gets "hot" before the stop lamp switch, there must be something else on the circuit with a problem.


Not got a US spec wiring drawing by me atm unfortunately.
SR Smith 1

Ive got an old ratty haynes thats battered to crap... let me know and i can try to copy the schematic and email you a copy on thurday on my lunch hour for you

you said ... 1979 usa spec ?

Prop
prop

Thanks
I got the brake lights and running lights working.
Where is the directional signal and hazard relays located?
ws Semko

This thread was discussed between 20/06/2016 and 01/07/2016

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