Hello, I've got a question that I need help with. I'm replacing the factory power antenna in my 78. I have a new power antenna I'm putting in, but it's the one for a 79-82. I made some new mounting brackets and have it mounted up perfectly beneth the fender. That took some time, but once I had it mounted, I though the hard part was over. The new antenna I put in had a harness/plug on the end that was apparently used on the later models, where as on my 78, it appears the power antenna wire run all the way under the center console. So I merely spliced in the wire from my new antenna thinking that would be all it would take. I matched up the white/green/grey from the new antenna with the white/green/grey factoring wiring. Since all the colors matched, I figured it should work.

Then I turned the radio on and the antenna went up and down, but I noticed the antenna motor got very hot. So I turned it off and disconnected the wires. After letting it cool, it went up and down again, but still got very hot and wouldn't go up and down after being hot. Anyone have any suggestions.

I've had far more trouble with trying to replace the antenna in my car then I could have ever imagined.

Does anyone have the Shop Repair Manual for the 78? If so, is there anyway you could possibly scan the pages that show the power antenna wiring? I don't have that manual and I think maybe it would help. I'd really appreciate it!! Any other tips or advice is greatly appreciated as well....thanks!!!

 

I've got the 78 manual and also have the79-80 manual but won' be back home until this weekend...I'm in Park City. When the power unit in my 78 acted up...I had it rebuilt but I recall the wiring on the unit. Seems that the 79+ unit replaced the 78 unit with the difference being the black plastic body. Your 78 should have an alloy housing.

Does it stay hot once the antenna is up? Or just when it operates?

Also the antenna retracts with two operations. Check to see if it operates correctly with each situation:

1. Car running, turn radio on and off. should go up when on and down when off.

2. With car running and radio on...turn ignition off. Antenna should retract.

I'll stay in touch and if you still need help, I'll look the wiring diagrams up this weekend.

 

I would suspect that if it is getting hot that it is somehow not turning of the drive current when the antenna maxs out, though I would think the fuse would eventually blow. See if you can get a vom or 12v tester into the connector and check if the drive voltage is remaining turned on.

 

Myself and a friend were buying up 78 antenna parts and non working units and rebuilding them(me) and selling them on Ebay(him) for a couple of years. 1 1/2 year item so kinda rare.
Anyway, came across some NOS aluminum motors at a good price. Got em and opened em up and NO limit switches. Were meant to be operated with a spring loaded switch. When up, release the switch, down, again, release the switch. If power was applied constantly, the motor would continue to run, depending on the direction of the switch.
With an automatic antenna, power is at the relay, but when the antenna is either up or down the limit switches will open and stop the motor even tho the wires at the antenna would still be "hot"(not hot to the touch, just live). When all the way up, the "up" switch will open and the "down" switch will close preparing it for when the relay says to go down.
Could you have gotten a "manual" antenna requiring using a switch? Even if the relay was bad, the motor would still stop when the limit switch opened on an automatic unit since the switches are controlled by a cam in the motor.
If it's not too much trouble, disconnect the 3 wires and try bench testing it.
To raise it, connect the grey wire to (-)and the green wire to (+). Keep power applied after it is all the way up and see if it shuts off by itself.
To lower it, connect white wire to (+), green wire to(-). Again, keep power applied till it shuts off.
If it doesn't shut off, your problem is the motor itself.
What happened to the previous antenna that it needed replacing? I'll guess broken mast leader? Easily fixable if the 2 large mast sections are in good condition. I'm about as far south from Chicago as you are north of the city. If it's fixable, send it down and I'll take care of it for ya. I've also got a couple good 78 style motors, too, and 2 complete 78 antennas.
Mike

 

There is an antenna relay located under the armrest on a '78. Radio wiring mates with the antenna wiring there.
Mike

 

Hunt4cleanair, if you have the manual showing the wiring diagrams, I'd appreciate that help. I compared what my wires were doing to what the wires on my uncle's 81 were doing and the white wire on my car is different. It needs to be + all the time (as on the 81), so I tried to splice it into the cigarette lighter. The antenna went up and down, but on the way down, the motor did not stop pulling it down once it was fully lowered. As a result, I think I disconnect or broke the piece that connects the mast to the motor. So I took the antenna out again and am going to take it apart to see if I can fix it.

Regardless, I am still not sure what I need to do to properly wire this thing, so if you have the manual and can let me know what it says, that would be greatly appreciated. This antenna has been such a pain, I should just slap a stationary mast on there and be done with it. Too bad I'm far too much of a detail person who has to have everything correct....thanks!!!

 

If you're working with a GM Delco antenna, if you have the white wire hot at all times, when you ground the grey wire you will cook the limit switches.
Mike

 

Here is a delco schematic. This should help you. What is the # on the antenna motor. If it a delco antenna, it will have a number. Delco made hundreds of antenna and some were not for GM. No telling what you have. Each motor has its own limit switchs and wiring. Some of the die cast motors are for Cadillac and those are DIFFERENT.

Also here is a pic inside a NOS 78 motor. Just pulled the antenna from the shelf for the pics.

Specializing in NOS / Restored Delco Antennas to NCRS specs. 78-82
NCRS Member.

Questions contact me at sigtauswt@yahoo.com