I’m not sure if anyone’s ever posted anything about this before, but I thought I’d share this.
If you have a sedan with power antenna and a OEM type spoiler, you’ll probably understand the reason for this. What happens is the spoiler will catch the power antenna and break the mast when closing the trunk. In some cases depending on clearances, the antenna might scratch the edge of the spoiler. Regardless, this thread is about how to wire in a relay to lower the antenna (when it’s up) when the trunk opens.
What you will need:
a Bosch 5-pin relay
5 blade connectors (make sure they’ll fit the terminals on the relay)
about 10-15ft of 12 to 16 gauge wire
2 butt connectors (or solder or heat shrink)
2 splice type connectors (or solder or some other sort way of splicing/tapping into a wire)
First thing to do is to access the power antenna by removing the trunk liner (or at least move it out of the way for easy access).
The next thing to do is look for the yellow/white wire that is connected to the power antenna. This wire is the switch wire that “controls” the antenna. The other two wires (blue/white and black) are what actually provide power/ground to the power antenna motor - don’t do anything to these.
Once the yellow/white wire has been located cut/strip the wire so that you have two open ends.
Cut the new wire so that you have roughly two equal lengths that can reach the trunk light. At this point, using the butt connectors (or one of the other methods described above), connect one end of each of the two halves to the cut/stripped yellow white wire.
Run/route the other two ends of the new wire to near the trunk light and cut off any excess (set aside as you will need to use some more wire later) Connect a blade connector to each end of the new wires.
Once the blade connetors are on, connect them to the 87A and 30 terminals on the relay. It doesn’t matter which wire goes to which terminal. On this particular relay, the 87A and 30 terminals mean that the circuit is closed (as in a completed circuit).
Take the two remaining pieces of wire and connect a blade connector to one end of each piece of wire. Once this is done, plug the blade connectors into terminals 85 & 86 on the relay.
Remove the trunk light so that the wires are exposed. Using the splice connector (or one of the other methods above) tap one of the new wires (either 85 or 86) into the green/black (positive) wire of the trunk light. Repeat this step with the remaining new wire to the other wire (negative)connected to the trunk light.
Terminals 85 & 86 are the “trigger” terminals. When current (power) is applied to these two terminals, the relay will open (disconnect) the current going through the circuit created by terminals 87A and 30.
In short, the switch circuit to the power antenna needs positive current. When 12 volts is applied to this circut, the antenna “knows” to go up and stay up. When you remove this 12 volts, it goes down. The 87A and 30 terminals on the relay simply bridge this 12 volt current so the antenna can operate normally. When current is applied to terminals 85 & 86 via the trunk light (ie. opening the trunk and applying power to the trunk light), the relay opens (interupts) the current to the switch circuit, causing the antenna to lower. When you close the trunk (turns off the trunk light), the relay re-establishes (closes) the circuit to the power antenna switch ciruit, causing the power antenna to raise again.
BTW, the fifth blade connector isn’t acutally connected to anything. Just plug it into the remaining terminal (#87) to give some extra protection.