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MG MGB Technical - Dead MGB GT 70 - Electrical

Hi from Denmark. I hope for some help here - thanks in advance. Today I wanted to perform a simple task - get rid off modern stereo and install a early 70s Blaupunkt - now the car is dead. Nothing works at all, starter, fuelpump, lights etc. The loom behind the dash has been modified to adapt the more modern stereo, with a multi connector and the work seems to be of a OK standard. As I was trying to locate the plus pole, the sound of the famous click ...... All 4 fuses in the engine bay - 35 AMPS are fine, any suggestions. Best regards. Per Rix - Denmark.
Per Rix Marcussen

Did you disconnect the battery earth cable before you started? If not you should have, if you did have you replaced it?

If the lights don't work it is something really basic as they are powered on the unfused brown coming up from the solenoid.

Check the battery connections, and the earth cable connection to the body.

Check the conenctions of the battery cable and the brown wires at the solenoid.

Check for voltage between the above 12v terminals and the body in all cases, don't just look at them and think they are OK.

Paul Hunt

Good evening Paul and thanks. It is now dark, so I will carry on tomorrow. I had the car connected to a external battery via jumpcables, when the little mishap occurred.
I have now installed a brand new battery and the cabin light came on, but before I could check other stuff, starter, lights etc - the power was gone again. I was able to to get the cabin light to flick by shaking the battery so I will primary check the solenoid and the brown wires tomorrow as you suggested. The car has been off the road for good while. I drove it last autumm to winther storage and this summer has all been work - the engine is out and should return to the engine bay next week - just about ready for wither storage in Scandinavia ......

Per Rix Marcussen

Succes - Thanks Paul. A good cleaning of the negative connection to the body did it - also !! Yesterday when I did put in a battery I did mange to mess up some wireing on the fuel pump. Regards. Per
Per Rix Marcussen

Jolly good. Waggling the battery to 'fix' it certainly pointed to a problem there rather than at the solenoid.

I had a bad connection develop at the solenoid during the annual test some years ago, having given no warning beforehand i.e. to me. The national chain of vehicle testers and repairers were totally stumped, when their booster battery connected to my battery didn't make any difference. Fortunately they left it on the ramp for me so I could remove, clean and remake the connections in about five minutes.
Paul Hunt

This thread was discussed between 26/09/2009 and 27/09/2009

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