77-78 Eldorado antenna relay

Started by jeffs7, September 15, 2014, 01:25:44 PM

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Antenna works with an aux power supply.
Dash switch is fed with radio and antenna power.
Dash switch sends power via 2 separate wires for up & down.
Relay will only allow antenna to go down.

Does anyone have a step by step diagnostic check for the relay?
I have a multimeter.

Everything ohms out well in all positions yet when the up is selected on the dash switch, I can't see why or figure out why it isn't sending the power out.
I've grounded the ground via sep line, contacts ohm, coil ohms well too.

R Schroeder

Don't know if any of this will help you.
When my switch is in the UP position, the antenna  is controlled by the radio, ON OFF knob.
Could be that your antenna is not in sink. ( see note ) It has not reset the switch inside.
That would be my guess.  78 book doesn't seem to cover the antenna to much. I'll snoop around in the 77 book.

Click on JPG below picture to make it bigger.



Contact Cadillac Tim.

He's the authority and he can explain if you have a bad relay.


Brian Rachlin
Huntingdon Valley, Pa
CLC # 22443
I prefer email's not PM's rachlin@comcast.net

1960 62 Series Conv with Factory Tri Power
1970 DeVille Conv
1970 Eldo
1970 Caribu (?) "The Cadmino"
1973 Eldorado Conv Pace Car
1976 Eldorado Conv
1980 Eldorado H & E Conv
1993 Allante with Hardtop (X2)
2008 DTS
2012 CTS Coupe
2017 XT
1956 Thunderbird
1966 Olds Toronado


Make sure the relay is being energized when the radio is turned on. Without power the relay defaults to the DOWN position, power goes through the white wire on the antenna. The limit switch in the antenna then shuts the antenna off when it is down. When the radio is turned on power goes to the relay and the relay then sends power through the black wire which makes the antenna go up. Again, the limit switch shuts the antenna off when it is all the way up. Turn the radio off, then relay goes back to default and sends power to the white wire to lower antenna.

Tim Groves