Radio goes off when I brake

[yttkuar]

I have had my 71 Ghia for 5 years with no trouble. Normal maintenance as a rule. PO changed ignition to use a push button device in addition to the key, which is first turned on then push the button. No problem with that either. It beeps when I turn it on and beeps three times after I turn it off. Except this spring after I bled the brakes I noticed that when I step on the brakes, the radio goes off. As soon as I release the brake the radio comes back on. It does that every time and does not affect the running of the car at all. I also noticed that the turn signal indicator light is very dimly lit now, it never did that before either. I did no electrical work on the car at all other than the tune up as normal. I did have the battery out to charge. Everything is fine electrically. I wondered of it might have been the brake bleeding process? Anyone had a similar condition?

[Era Vulgaris]

I'd venture to say that everything isn't fine electrically

Is your radio sharing the same fused circuit as your brake light switches and your turn signal indicator? It sounds like it might be
(the two fuses that share the black wiring in the 71 wiring diagram)
https://www.thesamba.com/vw/archives/info/wiring/70-71ghia.jpg

It sounds like there's an issue somewhere with that circuit, and there's only so much current draw it can handle, which is why the radio is cutting out when you hit the brakes.
When is the last time you cleaned all of your electrical contacts, including ground contacts? It might be time. In the process of cleaning, you might also find that something isn't correctly connected, could be anything.

But bleeding brakes would be a coincidence, unless you unknowingly did something to the brake light switch contacts on the master cylinder.
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Currently own:
66 Karmann Ghia, L390 Gulf Blue, under construction, here: www.thesamba.com/vw/forum/viewtopic.php?t=760505&highlight=
99 Mazda MX-5 10AE, Sapphire Blue Mica, 6 speed, LSD

Previously owned:
98 Porsche Boxster, silver, 2.5L -- 67 Karmann Ghia, Black, 1500sp -- 98 BMW Z3, Atlanta Blue Metallic, 2.8L I6 -- 75 Porsche 914, Laguna Blue, 2270cc -- 72 Porsche 914, Signal Orange, 1.7 FI -- 74 Karmann Ghia, Black, 1600dp -- 74 Triumph TR6 with O.D., sapphire blue

[yttkuar]

Thanks for the reply so quick. The PO installed the radio and the start button. All this time I have had it there was no problem. I did not mess with the master cylinder at all. I looked yesterday and the radio and brakes DO share the connection, so I will change it. I wonder tho, since they have shared it this long with no trouble, why it would cut off the radio when I brake? I do need to go through the fuse panel as you suggest. As they say, if its not broke don't fix it. Well, even doing regular maintenance in the spring, may have jarred something. I never have liked the button start the PO put in. I probably should find out why he did that too. No doubt it might have been not wanting to change the ignition switch. Thanks again.

[Trylon]

[hitest]

Ever hear the term, "the path of least resistance?"

That's what's happening here. It takes less current to light the taillights (a very amperage-tolerant circuit) than to power the radio (a very amp-sensitive circuit). You've probably already isolated the problem by re-dedicating the brake light power supply just for that purpose. Run a dedicated, fused line for the radio constant power- easy peasy.
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[yttkuar]

Thanks to all 3 of your replies. It turned out to be a combination of your suggestions. I may have jiggled something while doing my regular maintenance that set it off. After doing a good cleaning of the contacts on the circuits and isolating the radio, it works good again. I even had a blown fuse in the mix for the tail lights. As I said before, this Ghia has been great over my 5 years with it, so this was a pretty easy fix. Thanks again.

[Trylon]

Happy to hear you got it working— thanks for the update!
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1973 Porsche 914 2.0
1959 Volkswagen Karmann Ghia
1979 Volkswagen Rabbit
1973 Volkswagen Bus
1970 MGB-GT
1962 Oldsmobile Jetfire

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