MG Car Repair: Electrical Problem, trickle charger, regulator problem

Question
QUESTION: I just picked up a 1976 MGB last spring.  I drove it for the summer but from the day I purchased it, there has been a red (I think it’s an ignition) light that stays on when the car is not running.  

A new wiring harness was installed at some time in the past so I don't believe this will be an OEM problem.

When I start the car, the light goes off, but there seems to be something drawing power from the battery because I have to put a trickle charger every few days to keep it starting condition.  If I don’t (especially at night with the lights on) I’ll see the power drain as the lights start to dim and the engine starts to backfire.  If I turn the lights off, the power seems to increase for a while and the engine runs better.

Do you have any idea what the problem might be?

Thanks for your help;

Jim

ANSWER: Hi Jim,
The red Ign. light is a charge light and the first test is to disconnect the small wire/s on the alternator to confirm that it is not a wiring problem. If the light stays on then it is a wiring problem but if the light goes out then it is an alternator and/or a regulator problem.
If the light goes out when you disconnect the wire/s then put a volt meter across the battery posts and read battery voltage (12.5 to 13.5) and reconnect the wires and start the car and put the RPM at about 1500 RPM and read battery voltage. (13.8 to 14.5v) if that is not the reading you need a alternator. If you get that reading then you either have a minor leaking diode leaking or a regulator problem. (all internal)
Howard

---------- FOLLOW-UP ----------

QUESTION: Hey Howard;

Thanks for the answer to my electrical problem.  I am also planning to go through the break system.  Is there anything special I need to know before I get started?  I live in Michigan, so I have a few months to get everything in good shape for the summer.

Thanks again

Jim

Answer
The brake system is a dual circuit system but not complicated and everything is still available to rebuild the system if necessary. Not having the car long I would advise that you change the brake and clutch fluid and use DOT 4 fluid. (available at most any auto parts store)

Bleeding process is normal starting at the farthermost wheel from the master cylinder and work your way to the closest wheel. (Keep the reservoir up and DON'T let it run dry while bleeding)

Some times the clutch system can be difficult to bleed so a good method is to open the bleeder over a pan or put a hose on the bleeder valve and run that into a jar or can and open the bleeder and open the reservoir cap and just let it drain. Watch CAREFULLY at the level in the reservoir so that it does NOT run dry. AS soon as it is down to only a 1/4 to 1/2 full add new fluid and repeat the process until you see clean fluid draining and close the bleeder valve and fill the reservoir and you should not have any problems. If you let the reservoir run dry, air will enter the system and you will have to bleed the system which sometimes can be difficult.

Howard