Radio antenna - Part 1/2

[Kaz-kzukNA1]

Hi everyone.
There are lots of precious information regarding our radio antenna over the web.
I received a question from one of the member here and after discussing with him, I decided to post this as there seemed to be not much information on the JDM spec.
I only checked inside of the parts on my car (JDM) and all of the parts including the audio head unit are based on OEM so I will appreciate if you can use this information at your own risk.

1. Half mode
For the height of the antenna, there is an additional mode called ‘Half’.
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The antenna will stop at about 1/3 – 1/2 of its fully extended height. I guess this is not available for Acura or UK spec.


2. The Half switch (sw) and the wiring cable involved.
One of the 4 square slots in the centre console (where you have Fog light sw, Rear Fog sw, etc, depending on your model) is allocated for the ‘Half’ sw.
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There is a mating connector on the ‘Floor wire harness’. Although it looks like a 10pin connector, it is actually a 5pin.
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I guess this connector is not available for Acura or UK spec.
The switch circuit is very simple. Two pins are used just for the illumination and the remaining three pins are used for the switch. It’ll simply change the state of Pin-2 between ‘GND’ or ‘NC (No Connection)’.

Just this single wire at Pin-2 goes all the way back to the antenna unit. It is connected through the ‘Floor wire’, the ‘Side wire’ and the ‘Rear wire’ harness. Parts no. for these harnesses is different depending on the model and region.

Continues to Part 2/2....

Regards,
Kaz

[Kaz-kzukNA1]

Continued from Part 1/2....

3. Antenna unit
If you look at the antenna area inside the boot/trunk, you will see the followings;
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(from left to right on the photo)
- 4pin connector (grey)
- motor (round yellow/gold cylinder)
- control box (black plastic case, you may not have it on your car but not sure)
- position control mechanism (I don’t know the exact name and I could be wrong but I believe it is inside the silver disk shaped case below the motor.)


3-1. 4pin connector (grey)
The pinout of the connector (female) on the Rear Wire harness which connects to the antenna unit (male) is as follows;

Pin-1: GRN/RED
The single wire from the Half sw is connected to here.
On Acura or UK spec, you may find no wire at all or may be connected to something else. I didn’t check this.

Pin-2: BLK
Connected to the GND. Looks like the same for Acura and UK spec.

Pin-3; PNK/WHT
This is the wire from the audio head unit.
Looks like the same for Acura and UK spec.
Whenever the head unit is powered up, this wire goes to High and triggers the relay inside the control box. Thus, the antenna goes up even when you are not listening to the radio. Some people placed a switch on this wire to manually control the Up/Down of the antenna.

Pin-4: WHT/BLU
VB (Voltage Battery). Continuous power supply from the battery through 15A fuse.
Looks like the same for Acura and UK spec.


3-2. Motor
I guess this is the same for all models.

3-3. Control box and Position Control Mechanism (PCM)
I think the biggest difference is the Control box and possibly even the PCM between JDM and Acura or UK spec.
For some of Acura/UK model, the control box may be positioned somewhere else or not even used but I didn’t check this.
If you want to see the inside of the control box (like me), you can easily take out the control box with its bracket by removing just one screw.
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Please discharge the static electricity from your body before proceeding any further. Then, you can easily remove the lid at the top of the box and take out the circuit board inside. It just slides out including the white connector on the board.
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There are 4 relays for JDM. I guess there will be only 3 relays for Acura/UK spec but I didn’t check these models and as stated above, you may not even find the control box at all.

The 2 black relays (LZ series) are the ‘Up’ and ‘Down’ relay.

One of the sky-blue relay (RY series) is the ‘Motor’ and the other one is the ‘Half’ relay.

So, it’s a very simple circuit with just relays and a few diodes.
- There is no feedback circuit on the board for the height (down/half/up) of the antenna.
- The motor looks like linear and not stepping type.
Therefore, the control box needs additional input to switch on/off each relay otherwise the motor will keep running and not able to stop at the Half height.

The same goes for the fully Up and Down position.

Also, it needs a certain tolerance near each height (down/half/up) so that the motor won’t stop operating against friction and etc. before reaching the required position. For this reason and looking at the wiring diagram, there is a moving terminal contact or limit switch mechanism (PCM, in this post). I believe it is inside the round disk shaped silver case under the motor. I didn’t want to look inside so I may be wrong.

Based on above information, it is very likely that the control box and even the PCM is different from JDM to Acura/UK spec. As a reference, I have attached the photo of mating connector at the Control box.
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4 wires go to the 4pin grey Male connector (mating female is described in 3-1) and remaining wires go to the Motor and PCM.

I didn’t look inside of this round silver case (PCM) so I may be wrong but if you are brave enough, you may be able to adjust the max height of antenna by modifying one side of the terminal/limit switch position inside the PCM.

Above is pretty much how this radio antenna is controlled with additional information of the JDM Half switch. Although you may not be able to get some of JDM parts, I hope some of the information will help you on deciding your own requirement.


--- Side note; my modification ---

After all these, I took sometime to consider my own requirements. Every person has different taste so these are just my own notes.
- I normally don’t listen to the radio but I want to keep the antenna in case of emergency.
- I don’t like the full height of the antenna. I’m happy with just the half of it if I ever use it.
- Sometimes I use iPod interface to listen to the music so I don’t want the antenna to pop up under this condition.
- Whenever the audio head unit is powered off, the antenna has to be retracted fully.
- I want to keep the OEM antenna and I want to go back to original with ease if I made any modification.

Based on these requirements, I placed 1 extra relay just under the antenna unit and used the two wires (pin-1 and 3) from the 4pin Female grey connector to control the extra relay.
Now my antenna only goes up to half level when the Half switch is pressed (green light illuminates at the switch) while the head unit is operating.
The antenna stays/goes down whenever the Half switch is de-pressed (no more green light) even the head unit is operating.
The antenna stays/goes down whenever the head unit is powered off regardless of Half switch status.

Thank you.

Regards,
Kaz

[nigel]

Thanks for such a complete and in depth bit if information.
I will be getting mine sorted this weekend if time and the proper wire and connectors allow.
It has been suggested before here that you can find some "like" connectors at a scrap yard from other Hondas as they seem to use the same type connectors in different places on different of their models.
I have found some before this way and I will try again. I have found wiring with the same colour and tracer colours as well this way.
Thanks again for your help.
Any progress on the parts/part numbers or location for a headlight washer system?

Cheers
nigel