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Join Date: May 2006
Location: SF Bay Area
Posts: 90
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Radio antenna mind of its own
Here's a puzzler. The factory automatic antenna on my 78 SC sometimes works flawlessly. Then one time I'll turn off the radio, I'll hear a small clunk or click from near the antena, but it won't go down. I turn the radio and/or ignition on and off, fiddle with the wires, grounds, nothing, just a clicking noise at the antenna. Then, while parked, suddenly it will go down. Sometimes it takes 5 minutes, other times several hours or overnight. After that, it might work find for a few days, but then it will start doing it again. I've changed radios, same result. I've taken the antenna motor apart, and after that, it worked okay for a few weeks, but then it started again. I'm thinking it is a dodgey power or ground connection somewhere, but I haven't found it yet. Anyway, it always goes up, just not always down. Anyone else experience anything like this?
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78 911 SC 89 Range Rover 91 318IS 95 Ducati 916 86 Cagiva Elefant 5 bicycles Last edited by phiba; 08-22-2010 at 12:32 PM.. |
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08-22-2010, 12:27 PM
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Location: Manhattan Beach, California. Factory Delivery-Original owner-Retired engineer
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Quote:
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1986 911 Targa. Per Road and Track magazine: Only in L.A.: In the window of a bar in Hermosa Beach, California. "Happy Hour prices during all car chases." |
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08-22-2010, 02:33 PM
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Sure. What do you suggest?
Phil
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78 911 SC 89 Range Rover 91 318IS 95 Ducati 916 86 Cagiva Elefant 5 bicycles |
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08-22-2010, 04:34 PM
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Location: Houston TX
Posts: 8,702
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You are going to have a drained battery soon.
The antenna assembly runs battery power to the motor inside, and is only cut off when one of two microswitches is triggered (antenna up and antenna down). Everything in there is weak, and gets dirty/rusty/messy. Your switches aren't triggering well anymore, which means the motor has power and is either locking up, or running continuously. Pull the antenna assembly out (2 or 3 small bolts hidden up in the fender, some annoying wiring connections, and the top locknut that holds the mast in place). Open the box up (4 screws) and take a look inside, it'll make perfect sense then. clean and adjust as needed.
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Mike Bradshaw 1980 911SC sunroof coupe, silver/black Putting the sick back into sycophant! |
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08-23-2010, 06:48 AM
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Location: SF Bay Area
Posts: 90
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Mike, those are some good suggestions, and I'll try them. Next time it happens, I'll also use my multimeter to measure current draw in the antenna motor power wire. When it is stuck, I don't think it is drawing power, because my battery has never gone dead, even after weeks of being parked.
I'm wondering if there are some limit switches or relays in the antenna motor box that are making bad contact. Like one that tells the motor when the antenna is all the way down. Maybe on that first surge of power to close the antenna, it is going open circuit, which makes the motor think it is already closed. The strange part about that is it always eventually goes down, but that could just be the nature of the gremlins. Anyway, thanks for the suggestions, it has started me thinking more critically about the problem. Phil
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78 911 SC 89 Range Rover 91 318IS 95 Ducati 916 86 Cagiva Elefant 5 bicycles |
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08-23-2010, 09:11 AM
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