QuestionQUESTION: I have a large current leakage (approx 80 amps) to earth from Number 3 fuse on my 1972 MG Midget, chassis No. GAN5-93561. When the fuse initially blew, causing loss of indicators, tacho & fuel gauge, I simply replaced it and all was well at first. After about 15 miles, the fuse blew again and this time replacing it caused instant failure. I have disconnected the two green wires from terminal 6 of the fuse box and checked for earth leakage using a Gunsons Testtune meter with shunt. There is no leakage from the fusebox itself, but about 80A from the connector I removed. can you help and also tell me where the voltage stabiliser is, so I can check that.I have already checked the stop light switch, which seems OK. The fault exists when the indicator stalk is in the neutral position, so presumably the indicator circuit is not at fault.
ANSWER: Hi Mike. This is a serious problem. Something is earthing, and a current of 80 Amps is enough to burn out a wiring loom, so it must be traced immediately. Do not put another fuse into the fusebox until you have found it, and do not be tempted to fit a higher current fuse.
There are two green wires coming from fuse #3 (terminal #6).
One Green wire goes to the brake light switch on the bulkhead, then it continues to the reversing light switch on the side of the gearbox.
The second Green wire goes to a 4-way connector block, where it splits into 3 wires that power the voltage stabilizer, the rev counter, and the turn indicator relay. If you can trace this connector block and unplug all 4 wires, you can test each one to isolate the earthing fault.
If that doesn't identify a fault, then it must be the other wire. My guess would be the wire to the reverse light switch, but it could be the wire to the brake light switch.
You can ignore all other electrical components (such as the heater), because they are not powered via fuse #3.
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QUESTION: Thanks for your very quick response. I have already checked the brake light switch, which is OK,. Have you any idea where the 4-way splitter and voltage stabiliser are located on the midget?
I see you advise for the MGCC, of which I am a member, I have tried them for help but not been able to locate the Midget expert.
Mike
AnswerHi Mike. I very much doubt that the voltage stabilizer is causing this problem. It is far more likely that the power wire has come off the reversing switch.
The voltage stabilizer is attached to the bulkhead by a single self-tapping screw. You should see it if you look under the dashboard. It is a small canister about 2 inches wide by 1 inch tall, not very thick. There is a metal tag at the top where it attaches to the bulkhead.
From memory, I think the 4-way bullet connector is also under the dashboard. Look for a black plastic bullet connector with 4 plain green wires going into it, or try following any green wire. They all go to the same place.
Ignore the similar connector with 4 Green-and-Pink wires. That is the connector for the accessory circuit, and it goes to the fifth fuse (a separate line fuse).
The MG Car Club Midget Register have their own website and a Technical Forum. Follow this link:
http://www2.mgcars.org.uk/cgi-bin/gen5?runprog=mgbbs&access=&mode=tlist&subject=
