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MG MGB Technical - Help, I killed it, electrical problem

Facts- 1974.5 RB mgb roadster. Been running great, no issues except for a windshield wiper which worked only when I jiggled the switch. I decided to attempt a repair with the switch still mounted. I removed the steering column housing, removed the metal plate holding the switch innards in place, cleaned all contacts, and reassembled. Switch and wipers worked fine. No sparks, burning or blown fuses. Next tried to get windshiled washer working properly. Windshield washer motor ran but nothing came out of the jets. After cleaning I got that working. Bear in mind while checking these items I turned the ignition on but did not start motor. Wanted to go for a drive, key in, turn, fuel pump started running, turned to start and nothing. Not even a click. Tried again, same. Now I have no power at all, no lights, no horn, no wipers. Tried a jump, no help. Fuses are all intact. Where else should I check. I didn't go near the ignition switch and all wires appear to be connected. Help!
John M

John,

I'm not familiar with the electrics of your year but I'd check those fuses again. Run a continuity check on them or verify by substitution.
Paul Hanley

From what I've read, the headlights and ignition are not fused, through the fuse box anyway. I replaced the fuses anyway just to be sure, no help. Again I have no power to anything, no lights, nothing. Could I have done something to the battery, short it perhaps? I know very little about electrical systems.
John M

Hi John,

There'a a VERY comprehensive and easy-to-follow site that covers MG electrical issues:

http://www.mgcars.org.uk/electrical/

Saved my car (and my sanity) more than once. Good luck!
Chris Foleen

John,

If I were in your situation, next thing I would check are the battery terminals. Perhaps they are glazed over. Clean with battery terminal brush or in a pinch scrape terminals and leads with pen knife till you have plenty of shiney new lead exposed. You mentioned that your fuel pump runs? If so, maybe not the battery terminals but it can't hurt to clean them.

Paul
Paul Hanley

John, I have a 73 MGB and along with a lot of other fixes, I did the same thing you did. As it turned out, one problem was that I had a bad fuse and did realize it. The fuse looked good, but was blown. Also, when working on my wiper pump, I hit one of the wires going to the fuse box and realized that it was worn and loose. I redid the connection and it fixed the problem. Good luck.
Robert Browning

And clean the fusebox and tighen fuse connections while you're trouble shooting. I just finished working on a neighbors TD and the fuses were good but the contacts had scummed over and thus no current could pass. I used a dremmle tool and the small wire brush attachment. BTW, that's one job where safty glasses are highly recomended. Little bits of the wire fly off with increadable tenacity!

Good luck, John

Paul
Paul Hanley

John, Have you checked for voltages with a multimeter? You should start at the battery and go forward from there. If battery voltage is present at the battery go to the brown wires at the fuse box and check for 12 volts. If you tried jump starting with a pair of cheap jump cables, they usually will not start a car, even the good cables are sometimes hard to get connected well enough to get a jump. Make some voltage checks and let us know what you find. Fuses will not prevent the headlights and starter motor from working. FWIW, Clifton
Clifton Gordon

Thanks all, problem solved. Thank you Paul, I took your advice and cleaned and tightened the battery terminals. Power is back. Sometimes I forget to check the simple things before I panic and think it could be a major problem.
John M

Good job!! Take her for a spin in the morning! If you don't have a battery terminal brush they are dirt cheap. After cleaning and tightening, spray a bit of battery terminal protectant--permatex makes a good product. Pretty shade of purple too. Others smear petrolium jelly to keep out the O2
Paul Hanley

Chris:

Thanks for the tip on the electrics info site. I checked it out and added it to my "favorites".
J.C. Weidner

Another excellent site you want to bookmark or add to your favorites is Paul Hunts site The Pages of Bee and Vee. It can be found at: http://www.mgb-stuff.org.uk/
Onceon the site, click on Hammers and Spanners and then on Electrics. Cheers - Dave
David DuBois

This thread was discussed between 17/10/2004 and 18/10/2004

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