Anyone know how to rebuild a ‘75 Eldorado antenna relay?

[KWirth]

During a complete restoration of my 1975 Eldorado convertible in 2020 I had the power antenna professionally rebuilt.  At that time I also replaced the antenna relay with a NOS part.  Well now it looks like the relay is faulty again.  The antenna went up last time out for a drive but won't retract either with the radio on/off knob or with the antenna up/down switch.  I am not hearing the normal "click" when I turn the radio on/off which I think was typically the relay noise.  I understand that these relays can get "stuck" and was wondering if any members know how rebuild them.  If so, please let me know.  Thanks!

[benji808]

Hi!

Here is a thread that has the wiring diagrams for the radio and antenna:
https://forums.cadillaclasalleclub.org/index.php?topic=170127.msg529123#msg529123

I am not sure how to rebuild a relay, but here are a few thoughts:

1) the soft "thump" generally heard when turning the radio on is the speakers. Is the radio turning on at all? Do you get static if you turn up the volume? If the radio itself isn't getting power, then check the fuse and/or the power connection (I believe it's the yellow/blk wire on one of the connectors at the back of the radio).

2) If the radio is getting power, you should be able to test the relay to confirm that is the issue. If it is, you could try to open it up, but as you may know you can also likely find NOS relays on ebay for ~$50, which may be an attractive option.

3) If the radio is getting power, and the relay is operating correctly, then confirm that the wires at the antenna assembly under the hood are getting power. When the radio is turned on, power goes from the radio into the limiter cap which is part of the antenna motor assembly under the hood. That limiter allows the antenna to raise part of the way, then transfers power back to the dash switch, which allows you to raise it the rest of the way manually, and/or lower it manually. The limiter caps do sometimes burn out, which could prevent it from raising and lowering. Solutions are to get a new limiter cap (sometimes it easier to find a whole new assembly), or to wire the motor directly to the switch (but then you lose the automatic functionality and just control manually).

Let us know how it goes!

[cadillactim]

Make sure you have battery voltage at orange wire at relay. If not, check fuse. If you have voltage at orange wire check to see if the white wire or the other wire (not pink) has voltage. Relay defaults to white wire which makes antenna go down. Other wire (black?) makes antenna go up.

If white wire has voltage make sure antenna connector plus has good connections, they get corroded.

To see if antenna is okay put voltage to white wire and antenna should go down and shut off. Apply voltage to black wire antenna should go up and shut off.

Tim

[KWirth]

Thanks for all the info and testing scenarios.  I will go thru those once my garage warms up after this cold snap and let you know how I make out.  Always appreciate the help and guidance from this clubs members.

[KWirth]

Guys, It's been a while since I posted my question and thanks again for all your suggestions.  I followed each one of them and got everything working the way the antenna should.  Ends up after taking the antenna rely apart the contacts seemed stuck.  I freed them and cleaned up a bit (like with distributor points) and reinstalled.  Working perfectly.  Appreciate all your guidance in helping me figure this one out.