1977 MGB with electrical/starter problems

[DazWare]

We recently purchased our first MGB (1977). It ran fine for a short while, then we begin to have a problem. We had returned from a short trip and pulled into the drive and turned the engine off. For whatever reason, we turned the headlamp switch on while parked in the drive, and the engine turned over. On subsequent trips, if we attempted to turn the headlamps on while driving, the starter would engage. This also would happen occasionally with the turn signals and hi-lo beam switch as well. Now, the starter will engage when we are driving without utilizing any of the light associated switches.

Has anyone heard of this happening? Does anyone have an idea what could cause this?

Thank you for any advice or assistance.

Jerry A. Ware

[KimMG]

I have heard of this happening when the brake handle is pulled up. A couple people have reported their B's trying to run away from home. This particular problem is caused by an electrical sneak caused by a bad diode. Bad, corroded connections and grounds can cause alot of interesting problems. I would recommend disconnecting the battery until your cars problem is sorted out. Do you have a wiring diagram? I find the one in the Bentley manual to be the best. I photo copied the one for my car and enlarged it to make it easier to trace the circuits. Some people laminate large copies and use dry markers to trace circuits as they are working on electrical system. I believe faulty grounds in the lighting circuit can cause this kind of sneak. Check the battery cables make sure the connections are clean and secure. Especially the ground where it connects to the body.