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BT7 Mk I ignition switch short

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maineiac Avatar
maineiac Steve P
New Vineyard, ME, USA   USA
The wires on my ignition switch shorted out against each other while I was driving. The car died, I pulled over and the wires were smoking. I fixed the wires so that they weren't touching but I have no electricity now to any circuits except the horn. I checked the fuses and they are fine. I bought a new ignition switch and installed it but I still have the same problem.

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HBJ83341 Avatar
HBJ83341 Warren Voth
El Cajon, CA, USA   USA
Hi Steve,

I had a similar problem with my '66 BJ8. The BT7 wiring diagram is essentially the same as a BJ8. I had changed my generator to an alternator. In the process, everything went dead from the "dummy" voltage regulator to the fuse block. I installed the "dummy" to keep part of the original look. In the process, I did not realize that I did not make good contacts, when reconnecting terminal plugs to spade connections. Some of this was self inflicted, such as not pushing connections together for good conductivity. Also not making sure the spade was in the female plug, rather than between the spade and the surrounding insulation. Another problem is these contacts have not been touched in years and they have become corroded.

First, I would make sure that all of the contacts you have disturbed are good. These can be checked with a volt meter. I had removed the fuses and checked them to see if they were good. They were. When I returned them to the fuse block they did not make a good contact. After cleaning up the fuse block terminals and making both ends of the fuses made contact, power returned.

Check specifically which electrics work, and which don't. Do your head and tail lights work? If not. check the unfused side, probably the last terminal on the right side of terminal B on the regulator. Lights and turn signals are unfused.

Check the wiring diagram in the back fo your drivers manual. If you do not have one, wiring diagrams are available on line. Follow the diagram and recheck everything you touched while replacing and repairing your ignition switch. This can be frustrating, but you can do it. If I did it...anyone can...

Good luck,
Warren

maineiac Avatar
maineiac Steve P
New Vineyard, ME, USA   USA
Thank you Warren. I found the problem. On the backside of the voltage regulator there are metal bands that connect the terminals with the various inner workings of the regulator. The band for terminal A is burnt out - there is a gap in the middle. I bridged the gap and I got power, but things started getting hot really fast so there is still a short somewhere. I will have to dig deeper into the wiring harness by removing the cover and checking that there are no wires with melted insulation.

Steve

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HBJ83341 Avatar
HBJ83341 Warren Voth
El Cajon, CA, USA   USA
Steve,

If there is anything burnt out on the voltage regulator, you mentioned the bands on the back, replace the voltage regulator. I would not try to repair it. RB340 units are considered non repairable. Something is going on to cause that strip to burn out. And that may be causing wiring to get hot. A new regulator could be a really cheep fix...

Good luck,
Warren

petnatcar Avatar
petnatcar Silver Member Peter Carbone
Watertown, NY, USA   USA
Steve,

Remember to disconnect the hot lead to the coil while working on the electrics (unless the car is running)
or you'll have another part to replace.

Good luck,
Peter

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