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MG MGB Technical - Electrical Problems

After buying my 77 MGB the other day, I started exploring it more and found that I have almost no lights or anything working on the car. The headlights come on but no brake lights, no running lights, etc. The fan comes on in the car but thats it. And the turn signal does not work.

Where do you suggest I start? I used a probe light and on each side of each fuse I got electricity so the four fuses are good. Are there seperate fuses for the complete lighting system?

My Haynes MGB book is on order now since no one local has it. It just seems something common has to cause all of this since nothing works except the headlights.

And I'm missing a switch on the far left side which I do not know what it is but will find out when I get my manual in the mail.

Hope someone can help where to start!

Thanks!!!
Warren

Hi, I have a 77 B GT.
My turn signals did not work when I got the car (well, they worked sometimes) I took the turn signal lenses off at the front and then the two screws that hold the turn signal lamp itself in the front bumper (fender). pulled apart all the connections I could see and gave them a good clean up. Did this both sides and put them back together. result: working turn signals. Bs electrics are very exposed in this part of the car, years of road spray affect connections especially earth, you can have current all the way to a bulb but if it cant go to earth on the other side then it aint never going to work. Suspect similar work needed to Headlights.
Adam.
Adam

Warren,
Take your probe light and go out to the bulb holders as Adam states and see if you are indeed getting power to the filaments themselves. If so, then about all that is left are the grounding connections - always a black wire going somewhere to the bodywork of the car (the body, unibody, whatever, is the return path for all current in the vehicle and so for the juice to flow through the bulbs or anything else, their black ground wires much be screwed, bolted, whatever to the car body somewhere, somehow. So check these first.

However, if you find you do NOT have juice to the filaments (the end of the electrical path TO the lamp) then you have a disruption somewhere further up stream, heading from whichever lamp or other device is affected BACK towards the source - in this case the fuse block, since you know it has power.

As often happens on our cars, you may find you simply have cruddy or loose or disconnected connections somewhere in the harness to the lamps. If you have loose connections, think about renewing the barrel connectors as they often break apart internally and then have no further clamping action on the bullet connectors.

If all lamps are affected, you might want to check out the wiring connections at the fuse block itself for corrosion or broken wiring connectors for the lighting circuits.

In any case, Warren, just take your search slow and steady, and you will likely find the real cause of your problem. Also, some folks find it helpful to think of the flow of electricity as being something similar to the flow of water in plumbing. Electricity flows from the battery and then outwards from there to each device, each branch of the system, until it returns via the chassis back to the battery.

Bob Muenchausen

There are some black grounding wires in your trunk mounted near the license plate bolts. They may be loose or need cleaning. This is pretty common so you should check them first.
Terry D

This thread was discussed on 13/09/2001

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