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MG Midget and Sprite Technical - Lumenition Oprtronic Ignition Installation


Ive installed a PMA50 ignition to my MG midget and originally it worked OK, but if the car is left standing for a week it seems to kill the battery.

I think I may have connected the ''red wire'' to the wrong place on the fuse box. It says in the instructions feed side of ignition but am not sure which side this is ?

second point is that I have a resistor in place one wire leads from the positive side of the coil to the resistor but the other is a black earth wire there is no sign of an earth wire on the diagram.

if any one can send me some clear pictures of their installation (midget 1965) i would be very pleased or obviuosly some helpful comments

many thanks

Tim Fisher

Hey Tim........

6 pages of instructions................gotta love the internet!!

Sounds like you didnt wire it up instructions in the box??... or was that extra $$ ? HA!
M. Who

Thank M who,

Indeed I did get the instructions at no extra charge, good news eh ! Additionally am linked to the internet
its amazing isn't it ! but whats pdf and adobe ?? ;-)))

But seriously, am not good at wiring and find it difficult to understand the instructions. Yes I know its easy but for some reason I have a blackout on this one.

I have a fuse box and the instructions are asking me to connect the red wire of the lumenition module to the inginition FEED side of the fuse box but don't know which side this is. I guess trial and error are the anser but thought that someone could help along with the question I have on the resistor fitting..

Thanks for your help

Tim Fisher


Having looked at the following and upto 67 Midget MKIII.

I believe you need to wire it to the same side as the green wires as that is the the live side after fuse.


Shaun. The green wires are a fused circuit. My reading of Tim's comments indicates that what the manufacturer is suggesting is that the white wire circuit (unfused, controlled by the ignition switch) is the one that needs to be used. A good connection to the white wire circuit would be the wire that goes to the "SW" side of the coil. You can also tie into the white wires that feed the fuse box. This would be the wire(s) that provide power to the fuse which protects the green wires. (Have no Midget at hand to inspect, but this is the front of the lower fuse on the MGB fuse box and may be the same with the Sprite/Midget. Others can confirm or correct.)

Something is screwed up here if the battery is being drained. It could be because one of your wires is hooked up to a brown wire (hot all the time) which could drain the battery. Could also cause an electrical fire in the car's wiring.

Remove the wire clamp from the ground terminal of the battery and charge the battery. Get yourself one of these electrical test lights which has a pointed probe on one end and a wire with an alligator clip on the other. Connect the alligator clip to the ground wire clamp and touch the probe to the battery terminal. The light should be out (no current flowing) unless you have a clock or one of these modern radios in the car. If so, you might see a very faint glow to the lamp. If the lamp is glowing brightly, you have a short in the system which is draining the battery. Disconnect your new work (points replacement system) and check again. If you still have the bright light, you have a short you will have to keep looking for. If you do not have a bright light, you have a short caused by either a problem in the new points replacement system or have the system wired up incorrectly.

"second point is that I have a resistor in place one wire leads from the positive side of the coil to the resistor but the other is a black earth wire there is no sign of an earth wire on the diagram." How have you identified this as a resistor? Is it a medium brown with colored bands running around the outside of the cylinder? This was what resistors looked like back then and how they were marked to indicate their resistance. If it does not look like this it is not a resistor.

Back in the 60's it was common to attach a capacitor/condenser to one terminal of the coil to cut down on ignition system caused RFI (Radio Frequency Interferance) which sounded like static or bursts of static on the radio on some frequencies. I suspect that is your "resistor". Unless you have a very high quality AM radio system, the condenser is not really needed since most of us use FM radios today. Pull it off, diagram the connections, put it in a bag labeled to indicate what it is and where it came from and, after you have the points replacement system sorted, you can decide if you need to reinstall the condenser. Cars run fine without them in place.

Les Bengtson

I agree with Les about the feed wire but equally I do not understand your second point. a photo or a better desciption could help
Robert (Bob) Midget Turbo

Thanks everyone for your very useful comments, I'll take a look and let you know.

Tim Fisher

Have been away sorry for not coming back to you.

I wired it up to the white wire in the fuse box and now no problem. BUT will start a new thread on engine cutting out which I think has something to do with the resistor or something in the new ignition set up.


Tim Fisher

The red wire goes to the + on the coil, the black to the -

There is a white wire (perhaps mutilated by now) that runs from the other + lug on the coil to the tachometer. It's that simple!
Glenn Mallory

This thread was discussed between 24/08/2009 and 11/09/2009

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