Scion HU
- Thread starter CFR4RUNNER
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SeaKayak
New member
Diversity antenna not populated on Scion HU
I had done the heat sink modification, exposing the second antenna input on the Scion unit when I first installed it.
With the Scion HU out of the Runner to do a Dice iPod controller installation, I popped open the case to get a look at the circuitry, as I always wondered if the diversity antenna really did work on this stereo. After tracing down the antenna inputs, I found that the diversity antenna circuitry is not populated by Pioneer.
This make sense, as there is no reason for Pioneer to include the expense of the components, including the diversity antenna IC. The cost to Pioneer of these chips is probably in the $2-$4 range (DigiKey quantity pricing of a broadcast radio diversity antenna IC is at the high end of this range.) With the other components, installation, testing and manufacturing overhead, the cost of the entire circuit is likely in the $8-$15 range. This is not an expense that Pioneer would want to incur unless there is a requirement from Toyota, who would ultimately carry the cost. If you are selling tens of thousands of Scions, yada yada yada...
The mod to the Scion head unit will not gain you anything, other than a handy place to plug the second antenna lead.
The Scion head unit has a better feature-set than the stock Toyota, but you will sacrifice a little radio reception on one side of the vehicle. Probably no more than 3dB or so, unless the second antenna is meant to fill in a serious null in the primary antenna pattern. If Pioneer is using their Supertuner circuitry, then you may make up for the loss in reception if the receiver has better sensitivity than the Fujitsu-Ten. But that is another experiment.
Happy tinkering to all!
I had done the heat sink modification, exposing the second antenna input on the Scion unit when I first installed it.
With the Scion HU out of the Runner to do a Dice iPod controller installation, I popped open the case to get a look at the circuitry, as I always wondered if the diversity antenna really did work on this stereo. After tracing down the antenna inputs, I found that the diversity antenna circuitry is not populated by Pioneer.
This make sense, as there is no reason for Pioneer to include the expense of the components, including the diversity antenna IC. The cost to Pioneer of these chips is probably in the $2-$4 range (DigiKey quantity pricing of a broadcast radio diversity antenna IC is at the high end of this range.) With the other components, installation, testing and manufacturing overhead, the cost of the entire circuit is likely in the $8-$15 range. This is not an expense that Pioneer would want to incur unless there is a requirement from Toyota, who would ultimately carry the cost. If you are selling tens of thousands of Scions, yada yada yada...
The mod to the Scion head unit will not gain you anything, other than a handy place to plug the second antenna lead.
The Scion head unit has a better feature-set than the stock Toyota, but you will sacrifice a little radio reception on one side of the vehicle. Probably no more than 3dB or so, unless the second antenna is meant to fill in a serious null in the primary antenna pattern. If Pioneer is using their Supertuner circuitry, then you may make up for the loss in reception if the receiver has better sensitivity than the Fujitsu-Ten. But that is another experiment.
Happy tinkering to all!
gold4runner
New member
jharris2 said:Good detective work, SeaKayak! One question -- why do you think they included the jack if it's not connected to anything? Wouldn't it make more sense to save that expense, too?
Just curious about your thoughts on it. Thanks!
When I first put a scion head unit in the 4runner and only attached the one antennae I did not have the same reception as the stock radio. When I hooked up both cables to the scion headunit I did have better reception. So I have to believe that there is value in using both plugs, despite the good case presented a few posts back. The newer 08 scion radio only has one plug and I did not notice a difference in reception when I installed this radio with one antennae cable. my two cents worth.
SeaKayak
New member
jharris2 said:
The Scion head unit that I have has the circuit board designed to accommodate a diversity antenna...at least it appears to. The cost of having a special connector made to accommodate the same footprint could be the reason they kept the dual connector. Or, if they are like the places I have worked, keeping unique parts to a minimum is a metric engineering departments are measured by and the cost of carrying another part isn't worth it (drawings, procurement, obsolescence, and other like factors).
Great lookin' dog!
gold4runner said:
It could be that the Scion unit I have (a T1804) is not populated, but yours is. I may have been too sweeping in my earlier declaration that it isn't populated.
It also could be that the RF reflection from a disconnected lead is causing poor reception. The second antenna port could be terminated in the head unit, so plugging in the lead would improve the performance.
Setting a disconnected antenna next to one that is receiving or transmitting will effect the radiation characteristics of the operating antenna. This parasitic effect is what makes log-periodic and Yagi-Uda antennas directional. If you load the disconnected antenna, you can shape the overall pattern and even make the parasitic element electrically transparent.
Or an open lead could cause an imbalance in the 4Runner's antenna amplifier that deteriorates performance without the antenna properly terminated. However, I haven't read of any significant issues from people that use aftermarket head units that have only one antenna input.
I've thought about playing around with my three head units (original, Scion and FJammer) and see which one has the best reception, and to verify that the second antenna does help on my Scion unit and if the FJammer has a diversity circuit (the head unit has dual antenna ports, but the FJ Cruiser just has one antenna...I can't see that well into the FJammer to be able to tell if the circuitry is there). Without an RF spectrum analyzer, I figure a good way to do this would be to tune in a weak station, connect each antenna lead independently and both together into the head unit, and drive the 4Runner in tight circles in an open area to see which unit brings in the station the best and try to roughly determine the directionality of each antenna.
Or I could crack open a beer and watch South Park.
gold4runner
New member
jharris2 said:
The beer thing seems much better than the pursuit of knowledge. and thanx for the thorough explanation. merry xmas
Light_Mania
New member
A better test for the improvement a diversity antenna system is likely to offer would be performed in an urban environment. My understanding is that diversity antennas are intended to reduce the "picket fence" effect of radio reception where multipath effects (signals reflected from buildings) lead to very small areas of broadcast signal nulls, hence the "picket fence" effect as you drive in such an environment.
The second antenna in a diversity system is usually far enough away from the first one that it is outside the null zone, and the circuitry chooses the better signal.
As anecdote, my Scion head unit does exhibit a little bit of the "picket fence" effect that I never heard with the stock head unit, so I would not be at all surprised that it doesn't have the diversity circuitry, even though I have both antenna cables plugged into it (having drilled the backplate to access the second jack).
The second antenna in a diversity system is usually far enough away from the first one that it is outside the null zone, and the circuitry chooses the better signal.
As anecdote, my Scion head unit does exhibit a little bit of the "picket fence" effect that I never heard with the stock head unit, so I would not be at all surprised that it doesn't have the diversity circuitry, even though I have both antenna cables plugged into it (having drilled the backplate to access the second jack).
NCSCOTT
New member
HKpre86 said:
Yes. Plug a Mini-phono to Mini-phono (just like a head phone jack) into the plug in your center console and then you can select the "AUX" input. You can play any audio source through it that has a plug that matches. We play our portable DVD player through it and it puts out great sound.
That is how my 08 works anyway.
another scion
just won the bid on a scion single disk w/sirius sat equip for $98.98+20 shipping.
I'm happy. Wish it was XM so I'd get baseball, but what the heck.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=140211634244&ssPageName=STRK:MEWN:IT&ih=004
just won the bid on a scion single disk w/sirius sat equip for $98.98+20 shipping.
I'm happy. Wish it was XM so I'd get baseball, but what the heck.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=140211634244&ssPageName=STRK:MEWN:IT&ih=004
CO_FlyFisher
New member
Aux adapter problem solved
Just FYI - I have a Scion T1807 I'm about to put into my '99 Limited. I have a Aux cable I made up that plugs right in to the back of the radio, and works perfectly.
I plan to do the install this weekend, which will mainly consist of trimming about 3/8" of plastic off of each side of the dash bezel trim piece.
I will do a detailed write-up afterward. Look for it sometime next week!
Just FYI - I have a Scion T1807 I'm about to put into my '99 Limited. I have a Aux cable I made up that plugs right in to the back of the radio, and works perfectly.
I plan to do the install this weekend, which will mainly consist of trimming about 3/8" of plastic off of each side of the dash bezel trim piece.
I will do a detailed write-up afterward. Look for it sometime next week!
NCSCOTT
New member
I also have the T1807. The plug that the AUX input goes to is the same plug that the steering wheel controls tie to on the 4th gens. I just got one of these on ebay. See link.
http://cgi.ebay.com/ebaymotors/ws/e...STRK:MEWN:IT&viewitem=&item=200205485151&rd=1
This cable requires you to splice a few wires to the new connector to maintain the steering wheel controls. I personally will use solder and heat shrink. No butt splices here.
Ideally I would get the T1806 since it can control/charge the Ipod from the radio through a cable like below.
http://cgi.ebay.com/ebaymotors/ws/e...205484577&_nd1=&submit.x=65&submit.y=2&_fvi=1
Since I already have changed the radio twice in my 04 and my 08 is set up with just the AUX input factory, I will just make the AUX functional in the 04.
Toyota has also changed the shape of the Radio slightly in the 08s, Well I have the JBL and it is not the same at the bottom corners as the standard radio in the 04 anyway. Maybe someone with the standard radio in their 08 will know if they are the same shape as previous years. Since the Scion radio is not compatible with the JBL system, it is not a big deal.
http://cgi.ebay.com/ebaymotors/ws/e...STRK:MEWN:IT&viewitem=&item=200205485151&rd=1
This cable requires you to splice a few wires to the new connector to maintain the steering wheel controls. I personally will use solder and heat shrink. No butt splices here.
Ideally I would get the T1806 since it can control/charge the Ipod from the radio through a cable like below.
http://cgi.ebay.com/ebaymotors/ws/e...205484577&_nd1=&submit.x=65&submit.y=2&_fvi=1
Since I already have changed the radio twice in my 04 and my 08 is set up with just the AUX input factory, I will just make the AUX functional in the 04.
Toyota has also changed the shape of the Radio slightly in the 08s, Well I have the JBL and it is not the same at the bottom corners as the standard radio in the 04 anyway. Maybe someone with the standard radio in their 08 will know if they are the same shape as previous years. Since the Scion radio is not compatible with the JBL system, it is not a big deal.
Last edited:
sdsh
New member
ksneubec said:
It is from ProClip. Here is the link:http://www.proclipusa.com/vehiclemounts/vehiclemounts.aspx
There are two parts of the ProClip system. Part one is your device specific holder (Device Holder). Part two is your vehicle specific dashboard mount (Vehicle Mount). The Vehicle Mount attaches to your dashboard and then the Device Holder attaches to the Vehicle Mount. I just bought the Vehicle Mount and reused my existing holder. I attached the holder to the ProClip mount using Industrial-strength Velcro tape. I like this mount because it is stable and was tired of the vibration of my old gooseneck windshield mount.
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