Just installed a new rear wiring harness and new power antenna. My antenna goes up but will not come done. Any suggestions? I have power to the new rear harness. I have not been able to check the down power at the antenna.
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Re: 66 Corvette power antenna
Ken -
Do you have both up and down power at the switch? And on both sides of the body harness connector above the kickpad? -
Re: 66 Corvette power antenna
Yes to both.Comment
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Isn't that interesting!!!
The '65 setup is identical, so I cracked open my '65 AIM to pitch in here and wonder of wonders, the wiring diagram is wrong/incomplete! It shows cockpit power going to the antenna switch and then through the dash harness to the connector for the rear harness.
But, at the rear harness connector BOTH lines that feed the power antenna are depicited as UNCONNECTED! Soooo, a quickie review of the 1965 Chevrolet Radio Service/Shop Manual followed. Full disclosure on the radio but narry a word about the power antenna.
Now, there were only two versions of the rear lamp harness in '65 (with or without optional backup lights) and that means both were equipped with power antenna wires. Sooooo, we've got a case of documentation 'opps' that looks like a Body by Chevrolet vs. Body by Fisher lack of attention to detail!
Well, enough said there. Back to Ken's original post. There are only two wires feeding the power antenna. One is power up and the other is power down. The antenna gets its ground via a discrete ground strap connecting the antenna motor bracket (Item 6) to the frame. This connection should be shown in your AIM book, Option Section, UPC U69, Sheet B2, View A.
Note the relative placement of Item 5, Lock Washer, relative to the ground strap and its attaching screw. Assembly must be in this configuration in order for the ground strap to 'bite' through paint on the chassis and give the antenna a proper ground reference!
Plus, good contact also needs to exist between the ground strap and the antenna frame as well as between the antenna frame and the antenna assy itself. We often jump to the conclusion that because a motor works in one direction, the ground reference MUST be OK. But, you really should verify because odd things sometimes happen with power seeking/finding alternate path(s) when grounds are faulty, like back through a capacitively coupled antenna lead-in cable to/through the radio chassis itself...
The power antenna is driven by a DC motor (actually the same unit as used on the headlight buckets) which has a split-winding configuration. Ground is connected to the motor's center tap and the up/down switch simply routes +B voltage into one end of the motor's winding or the opposite end to make it sping clockwise or counter-clockwise.
The most common problem that creates the symptoms reported (motor only runs one direction) is either a bad control switch or a faulty wiring connection (perhaps a bent pin/loose pin in the mating connectors between the dash and rear lamp harness located behind the LH kick panel).
But, it's possible to have a faulty power antenna ground connection at the frame. AND, while a pretty darn rare happenstance, you can have a faulty power antenna with poor wiring integrity at the harness interconnect junction.
The BW to troubleshoot is to:
(1) Verify the antenna's ground integrity between the support bracket motor and frame.
(2) Next, disconnect the rear lamp harness at the antenna and verify power DOES come on properly and repeatedly IN BOTH lead wires from the rear lamp harness RELATIVE TO the chassis ground at the antenna mounting bracket.
(3) Last, with the antenna disconnected from the rear lamp harness, exercise it with a known good power source (another battery works nicely) by connecting the independent power supply's negative or ground terminal to the power antenna bracket and touching its positive terminal to the lead wires on the power antenna ONE AT A TIME....Comment
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