Whitmanpc1

Does anyone have a wiring diagram for the antenna for the 1993 SC400 please?

I replaced mine with a $50 after market antenna and wish I had spent the $300 on the Lexus one. Crazy, I still can't get it to behave the way it should. It's getting there, but something is still not right.

Thanks!

captclam

If you can wait a week, I will have it for you!

Kirk

Whitmanpc1

Kirk,

Thank you so much. I can certainly wait a week, as this is a long term but not serious issue (well mentally for me it is!!).

Thanks so much! My email is Whitmanpc1@mediaone.net.

MrWigggles

Yes the service manual is great for antenna problems.

If you hold down the am and CD buttons as you turn on the car, the power antenna will eject your mast!

Mast replacement is pretty easy on this car.

-Mr. Wigggles

933005spd

Give me some details, maybe we can help

DoubleWhoosh

The problem with the antenna is that the orignal uses a reception dependent adjustment, where the unit will go up and down to find the optimum signal.

Even the regular Toyotas will actually have 2 wires that control the antenna. On those, you need to attach 2 wires that go to the antenna to the output from an aftermarket head unit.

Your situation is not only opposite, but also difficult, as the Lexus system is more complicated.

If you have access to a multimeter (NOT a test light!), try to test the following wires in the harness going to the original antenna:

Pink/Green, Pink/Blue, Yellow/Red, Blue/White

See which of those has 12 volts the whole time that the stereo is in AM A-N-D FM modes.

I think just one will do it, if not then post back with the results and I'll let you know the next step.

Todd Matsubara
TM Engineering
http://www.tmengineering.net

GOLDSc300

I am trying to replace my broken antenna mast. I unscrewed the chrome bolt, and turned the radio on, but I can get the mast apart from the motor. The actual mast comes off, but the plastic spiky thing stops when the motor stop, and I cant pull it it out. Any suggestions? Thanks

GOLDSc300

What if you dont have a CD button. I have a 92 that didnt come with a stock CD player.

pcmw

Just slowly consistent force pulling straight up should allow the motor to release the last few teeth on that mast. Also, make sure your radio is on 107.9

MW

GOLDSc300

Still wont come out. No matter what force I use, it just stops. I was thinking of taking off the motor and taking it apart, but what good will that do?

pcmw

gold,

I think you have other problems if it does not come out easily. You may want to drive to a stereo shop or your dealer and seek advice. I would think that if your antenna lost a few teeth in the motor assembly that it could have jammed the motor. Another possibility is that your antenna motor was not setup correctly when the mast that is in there was installed. I would suggest trying this scenario if nothing else works. Turn stereo on, pull mast as far as it goes, unplug power antenna motor, shut stereo off, plug back in, and turn on again. You just need to rotate the cog another few inches to release.

MW

mhawk

It is a very simple process to remove the whole mast. Turn off radio, Remove top hold down above the fender then only one screw that hold the motor to the mounting bracket. Unplug wire harness and antenna lead. Move to a work bench unplug harness from motor to blue colored elect. box. Remove four perimeter screws, there is a single bolt and nut that runs thru the center of motor box. The cover can now be removed and any broken bits/pieces can be fished out by hand. Reverse to re assemble, place back on fender, feed the plastic tooth lead in as someone turns radio on, may have to turn teeth towards gear if it wont bite.

GOLDSc300

Well finally we replaced the mast and got it working. Pulling the mast out was the hardest part. We ended up taking the motor apart and cutting the plastic spiky think off. I dont know if this job was easy for anybody but we had lots of trouble doing it. Anyways, thanks to everyone who gave us advise and suggestions. Later.

sparkyguy

Not trying to hijack an old post but I have a similar problem. I'm trying to re-use my OEM power antenna on an aftermarket stereo.

I'm replacing a very dead and hacked Nakamichi "Premium" system with trunk amp & CD changer (meaning it got wet, fried and the previous owner has left me with loose wires, corroded amp, etc.). I'm replacing it with a Pioneer Double-Din stereo in my '93 SC400 ALL of the old Nak equipment has been removed from vehicle. My only issue is with the antenna and whether I have a bad power antenna or wiring.

I've verified the motor DOES run by directly powering it on a workbench while I replaced the mast & whip.
I did this by unplugging the power connector AT the motor by carefully connecting a battery directly AT the motor bypassing ALL of the control wiring. One polarity makes it rise, the other retracts it. Motor is OK.

The OLD nak diagrram i found (on this site), has 3 conductors shown in dash for antenna.
They are labeled as follows
B4-BLU/WHT (ANT A)
B10-YEL/RED ANT B)
A10-PNK/GRN (ANT).

I've located both the "A" and "B" connectors and all three conductors in the dash behind the old NAK head unit. However, my new stereo has the typical SINGLE blue conductor for antenna control which gets powered when the new stereo is ON. One by one, I've tried to temporarily power all 3 conductors, but the mast won't rise. I've connected all 3 together and then powered all three at once with no results either.

Am I correct that ONE of these combinations should normally control the antenna?

If I had a ANTENNA internal schematic diagram it would help, but the don't seem to be around internet.
I suspect either defective wiring or the control box mounted ON the antenna is defective. However, since I don't know HOW the original unit functioned, I don't really have any way of bench testing it any further.

Has anybody re-used the existing power antenna on an aftermarket stereo?
How did you connect it?

Duck05

As this thread indicates, the OEM unit "adjusted" the mast for the best signal; pretty nifty feature for a 90s car....

When I replaced the OEM head unit with a Pioneer DD (2012 model) the shop used a harness specific to our cars and getting the antenna to raise and lower worked fine but the subtle adjustment feature was eliminated.

The "bad thing" was the antenna raised and lowered when the DD unit received power and for the most part I almost never use the radio in favor of an iPhone running Pandora or the micro chip with over 8GB worth of music. Really did not want to have the antenna go up and down every time the car started and stopped.

Instead, I had the shop wire in a simple toggle switch (buried in the ashtray) and on the rare occasion when I do use the radio (like a basketball game - GO Warriors) a simple click raises the mast; another lowers it.

Sorry I can't provide specifics on the wiring but the harness seemed to solve all those issues.