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MG MGB Technical - Fuses blowing

I recently had my 1978 mgb body redone. The guy did a great job on the body. Looks fantastic. But he took out the electrical harness and now the fuses blow for the speedometer, fuel gage, turn signals, etc.
I replace the fuse and all comes back on but when I turn the car off and start it up, the fuse blows.
There are other electrical problems I am trying to figure out.
I am affraid he didn't hook the harness up properly.

Wondering if anyone has any suggestions. A new harness?
Any suggestions are greatly appreciated.
Mari Jo Pesch

Mari, try this site. It is the one that everyone else on this BB recommends.

http://www.advanceautowire.com/

Click on the Stock Schematics link in the left hand window and find the diagram for your year/model and away you go. It's nicely colour coded and very easy to follow.

Cheers

Tony
Tony Oliver

Mari, try this site. It is the one that everyone else on this BB recommends.

http://www.advanceautowire.com/

Just find the diagram for your year/model and away you go. It's nicely colour coded and very easy to follow.

Cheers

Tony
Tony Oliver

Given the work that has been done it could be absolutely anything, and there are so many components and branches on the green circuit you are likely to be still scratching your head after looking at any diagrams.

Unless he has actually damaged the harness a new one is only going to give you more work and expense, and if you could cope with that work you will be able to diagnose the problems with this harness.

A common problem of blowing the green circuit fuse is the sub-harness feeding the brake light switch getting trapped somewhere, on a 1978 with servoed twin circuits the switch is in the cabin by the pedal.

Another cause is the inlet manifold heater wire trapped or just dangling, which could be shorting out when the engine rocks on starting.

Other than that it is a matter of splitting the circuit into separate halves, starting with the two green spade connectors on the fusebox, and seeing which one blows the fuse. Rather than keep replacing fuses, and if you can regularly and repeatedly reproduce the problem just by starting the car or if the fault stays on, you can replace the fuse with a high-wattage lamp like one half of an old headlamp bulb. If it glows brightly the short is present, if only dimly or not at all it isn't.

Whilst the autowire diagrams lay components out more conveniently for seeing what switch operate which component you will need the originals for the full sequence of 4-way bullet connectors where things split off.
Paul Hunt

thanks guys...I will take all of this info and with a friend of mine who loves working on my car start working on the problem solving.
more later.
Mari Jo Pesch

This thread was discussed between 21/07/2009 and 22/07/2009

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