NewbVetteGuy

My 79 still has the original radio, speakers, and power antenna and has not been "bubbad" (yet, anyway).


I'm honestly getting decent reception for the station I care about with the antenna still down but I want to fix the power antenna.


I've read around a bit on these very common problems and here's my current game plan: someone please verify / correct my plan:


1. Have someone turn the power on to the radio while I listen to see whether it sounds like the motor is trying to make the antenna go up or not
2. If not- get a volt meter and set it to 12 v and check for power going into the antenna motor -above the driver's side muffler
3. If no power at antenna motor check the relay- the location varies and on 79 is inside the center console by the parking brake (80-82 it's in the jack storage compartment)
4. If power is coming into the relay but not out of it; it's a dead relay-replace; if power is not coming into the relay but the radio has power go to #5
5. Check the output from the radio to the relay (I have no idea where this is but I hope I don't end up getting to #5 anyway)

The antenna is powered off of the accessories / convenience circuit -so if the dome light works, it's not a dead fuse issue.


Obviously many of these troubleshooting paths may require additional "branches" and testing activities but this is my 1st pass game plan.

Adam

SwampeastMike

That will work except there's no way to check for power at the antenna itself. (In a way that's a good thing as it's a paint to get to.)

Remove the driver side rear speaker and you'll find a three-connector electrical terminal in there behind it. I believe the wire colors are black, white and green. Black is ground. The relay provides +12V to one of the other wires (depending on up/down). "Kick" limit switches in the antenna mechanism stop the flow of power when the mast is either full up or full down.

The relay is easy to get to in a '79:

1) Remove both carpeted side console panels (3 screws front, middle, rear) in each. The carpet pile can hide the screw heads surprisingly well.

2) Remove two screws (one each side) from the parking brake cover housing.

3) Remove two screws (both at the front and going into the shifter bezel) from the parking brake cover housing.

4) Remove the parking brake cover housing

The relay is behind the parking brake handle/mechanism.

It's extremely common for the nylon cord inside the antenna to break. When this happens the motor will run continually. Don't be surprised if you find the antenna disconnected either at the relay or at that connection behind the speaker.

hunt4cleanair

You have a good plan and Swampe's instruction will gain you access to the internals.

Here are some specifics to 'bench test' the antenna in the car.
Pull the white/green/gray connector out of the relay, and with a couple of wires directly to the battery try raising and lowering it. There are limit switches inside the antenna that SHOULD turn it off when it reaches it's up and down limits.

To raise the antenna
green +
Gray -

To lower the antenna
White +
Green -

If it continues to run in either direction it's the antenna.

To drop the antenna motor, pull the driver's side rear wheel...helps with lighting and access but rather straight forward.

Keep us posted and hope this helps!

Shark Racer

At some point in the life of my car, the antenna was replaced with a 79 MY antenna motor (I think). If yours is original, you can source a rebuild kit from "AntennaMastsRUs", that's what I did. Pretty straight forward to rebuild, drilling out the rivets was a minor pain.

MarkinSETX

Dude... Thanks for the tip. The antenna on my 81 suffered the broken nylon piece. The motor whites but no movement. I have been looking to replace it, but will try the 25 buck rebuild, since the original part will be easiest. Thank you for the website.

Shark Racer

No problem. The one time in my life something broke conveniently. A week or two before my EFI swap, the antenna cable broke. I was already planning on dropping the exhaust to do the gas tank.

My usual luck would have it break the day after I put everything together.

gdt3

My motor didn't whine, but I took it out and apart anyway. It turned out that a piece of the nylon line was jamming the gears. Replaced the line thanks to all the help on here and it is working fine. Now I just have to put it back together.