MG Car Repair: 1979 MGB Tourer / Electrical problem, windshield wipers, turn signals

Question
The windshield wipers ,turn signals,horn,will not work.The car starts and runs great. The radio works as well as the dash lights,also the rpm gauge quit at the same time.whats going on?. Thanks Wayne

Answer
Hi Wayne,

That could be anything of a hundred things but I can tell you a 100% fail proof method to fix it.

First you need a wiring diagram and a test light. I learned in the dealerships I worked in to pick ONLY one circuit of several failed circuits and start at the load (the item that don't work) and pick the easiest circuit. (probably the horn in your case)

I always start at the load and work my way toward the power source. Some mechanics go the other way. If you look at your diagram you will see that the horns are powered and the horn push grounds them. So look at your diagram to see where the horns get their power from and start by testing the horns first and if they do not have power use your test light one connection at a time and head toward the power source. If the horns are powered then start testing the ground wire up toward the horn push to see if it grounds the horns.

Most of the time when you have several items failed, when you find the problem with the ONE circuit you trace, you will find the problem with all the failed circuits.

This method can not fail. If you fix the horn and some of the others still don't work then pick a second circuit to trace.

If you don't have a diagram, let me know and I will post one on my web site for you to copy.

Howard