MG Car Repair: MGB Wiring, alligator clip, cylindrical device
Question
Electrical Device
Howard
I'm working through almost 40years of cobbled up wiring and neglect in my 71 MGB GT. I've been able to get most of it cleaned up and back to working condition. When fixing the wiring in the center console, I came upon a device connected to the wiring harness that I can't identify via the schematic. It is a cylindrical device that looks similar to flasher unit but greater in length. It has no markings on it (either painted or stamped). On the bottom, there are two terminals marked C1 and W1. It is bolted to the dash behind the center console. Basically behind the console light fixture. There are two wires connected to the device.
I know this is a factory fitted item because I have a spare harness from another similar GT and it has the same device still connected to it. I can't for the life of me figure out what this is and what it does. It's not the hazard flasher, turn signal flasher, or voltage stabilizer. I don't think it's a relay because it only has two wires to it and they are both the same gauge (about 18 or so). Sorry, I'm pretty color blind so I can't be sure about the colors. (when tracing out wiring I usually enlist the help of my wife or daughter to verify colors when necessary LOL) I'm attaching a photo of the device for your review. Sorry it's blurry but I suspect you'll be able to identify it from the photo.
Thanks in advance.
Dave
AnswerHi Dave,
The only devices I ever seen in MGs like that are either flasher units or warning buzzers.
It is easy to test. Apply 12v (+) to one post and a brake light bulb to the other post and ground the case of the bulb to (-). If it lights the bulb and it starts blinking it is a flasher unit and if it starts to buzz, it is a warning buzzer.
I like to use the warning buzzers as test units in a power test lead. I use a heavy gauge wire to an alligator clip and the other to a in line fuse and from the fuse to another alligator clip. Then I put in parallel a small test light and also in parallel a warning buzzer.
When working in a car like you have now I remove the power supply (either at the battery or at a fuse etc)and put my test unit in place and while I am testing and working on wiring if I accidently short something out and blow my fuse in my test unit it will light my light and set off my buzzer. Thus alerting me that I have popped my fuse. It saved me a lot of burned wires while working. A better unit would be to replace my in-line fuse with a circuit breaker.
My guess it that you have a warning buzzer there.
Howard
