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MG MGA - re-wiring issue

Electrical issue. had a minor engine compartment fire (if you can have such?). All electrical wiring from firewall forword must be replaced. Have electrical skematics, however they don't show routing.
any ideas where i can locate this information? perhaps someone on this board might have detail pictures or a schematic that I could obtain or someone might know of another source. also i would ask is their a source out there who sells a harness for firewall forward, Any ideas or comments welcome, I surely need the help.
this board has been sooo much help over the years thanks,
garry irwin
berea, kentucky

gei irwin 1

The supplier of the best wiring harnesses is:

These can be expensive but they are the best quality.
It is worth sending them some questions.
As the company is in Australia you should mention that your car is LHD.

M F Anderson

How did the fire start Gei?
Lindsay Sampford

Non fused lighting circuit at a guess?
Bob Turbo Midget England

Here's a picture. My best guess is you need to replace the main harness. There are a number of wires that go to the gauges as well as engine compartment components. They are all wrapped together. Determining which wires you need and don't need could be a nightmare.

Good Luck.


I agree, the easiest way is just to fit a new harness!
Neil McGurk

Hi, Fitting a new harness isnt as difficult as it seems. If you use the wiring diagram to label all the wires in terms of what they connnect to, it is a fairly easy job. Using the tagged harness, routing of the wires becomes pretty obvious, especially if you are careful removing the old harness, and observe how it is routed. Installing a new harness can generally be done in a day or two, including removal of the old harness. You may bump into a few wires that dont seem to attach to anything, but rechecking the wiring harness against the wiring diagram colour coding, usually allows the solution to be found. I rewired my 1500, and I believe anyone who can follow a colour coded wiring diagram, could probably do the job. cheers, Glenn
Glenn Hedrich

In the US a good supplier is British Wiring (
Dave McCann

All great stuff- but colour blind- a bit of a bummer -so I get to lure my wife into the shed and point out which is which.

Something that statistically will rise over the millenia as it's a male dominant, female recessive gene!

So rewire NOW!

Todd Clarke has routing diagrams for the harness, and depending on how bad your fire was, can provide correct clips and other hardware. British Wiring is a good supplier for harnesses, and they should be able to get you a connection diagram as well.
Mark Lambert

mark lambert: i can't seem to locate Todd Clarks mailing address or phone number! know of him from years past, good man. if you have address and phone number it would be of real help to me, tks
garry irwin
gei irwin 1


Here is the link to Todd Clark's web site, .

jjb Backman

thanks john, for the clark info i'll contact him immediately. garry irwin
gei irwin 1

Digital cameras are great for working on these cars!! (Obviously I'm a senior person, old fashioned ways etc. Digital is a great new trick for old dog!)

Take lots of pictures of the old harness in place before taking anything apart. Take pictures as you take it apart. Clean all connections before or during instalation of the new harness.

I know it sounds obvious, but do remember to disconnect the batteries!

On of the most common occasions for the engine wiring fire is leaving the ignition on without the engine running. If the points are closed it produces a direct short to ground for the ignition circuit. I remember putting out a primary wiring fire on my old Bug Eye (listening to the radio while washing the car) with beer. Shameful waste of beer!
Russ Carnes

One additional suggestion is to cut the old wires about an inch from the end rather than completely remove them. That way you will know what colour was connected to each terminal when you install the new harness.
John DeWolf

This thread was discussed between 12/05/2010 and 26/05/2010

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