FC Power antenna relay test
 

I think my antenna relay is bad. I'm talking here about the relay that is mounted on the antenna itself, not the added one that reverse polarity.

I've checked the motor and winding mechanism and it is good.
The car loom is OK

When I connect the antenna to the car the motor starts even there is no radio and the car is turned off.
There is some information in the service manual how to check the relay, however the plug on mine is different (8 pin vs 10 pin)

Any ideas how to check or repair it?

How many wires is in your plug and what year is the car?

Car is a 1989 EDM convertible turbo

However the antenna I'm talking about is from an unknown convertible USDM car.
The strange thing is that the antenna relay is not a green box but a bigger transparent one.

There are 9 wires in the plug (in the one that goes to the relay)

The wiring diagram shows the S5 should have 4 wires in total. Your version appears to be completely different.

4 wires are in the plug that connects to the car loom.

I was talking abut the plug that connects to the relay on the antenna. I'll make a picture later.

Then what do the 4 wires connect to?

To the plug in the trunk.

It goes like this: trunk (4pin) -> relay (10pin) -> motor (3pin)

I believe the 4 wires end up at the relay thus you need to focus on these 4 wires first and if they check out okay then the issue is likely found within the relay itself. And a pic isn't necessary as I found the illustration on page 104 of the body electrical section of the FSM.

Unplug the 4 wire connector and test the 4 wires and if they test correctly then the issue lies within the relay or quite possibly the ground wire for the relay. Prong C, as denoted in the FSM, is the ground thus there should be continuity between this wire and the body.

What is the correct key position for the antenna to work? I.e. when the anntena should raise and lower.
Off? Acc? On?

Off -> will remove power and the antenna should lower
Acc -> Radio off = antenna down, radio on = antenna up.
On -> Radio off = antenna down, radio on = antenna up.

The wiring schematic will also flush this out. When in doubt, consult the source.