I am trying to install a new head unit in a japanese model 94 Rav4.
There is something strange going on with the wires that were going into
the back of the previously installed head unit.

The plug on the back of the old unit wasn't the same as that on the new
(Panasonic) unit. So I cut the old plug off and installed push on
connectors on each of the wires.

I've found the gnd wire and the always on and on-with-ignition 12V
wires. But I am having trouble with the remaining 9 wires.

I tried connecting the output of one side of the head unit to every
combination of pairs of wires (I known not a good idea). That sometimes
resulted in sound at each of the speakers, but overlaid on top of that
was a heavy rumble of electrical engine noise.

On further investigation there was 5V present at 5 out of 9 of the
remaining wires. That left 4 wires with 0V present (as I would expect
for speaker wires) However as there are 4 speakers I should expect to
see 8 wires available. I tried outputting a signal between each wire and
earth, but that produced no result.

I also opened up the door panel and checked for continunity between the
speaker in the door and each of the wires. None of them showed a
connection.

So there is something strange going on with the speaker wiring. The old
radio (a Mitsu****a or something I think) worked fine (well for a Cr*ppy
old radio at least).

Anyone seen anything like this before?

Pete


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The only thing I can think of is there is a factory amplifier in the vehicle. Easy way to know is if there was only one plug behind the radio. Typically most US models of Toyota's will have two plugs for non-amplified systems and one for amplified systems.
"Peter Grooby" wrote in message .. .
I am trying to install a new head unit in a japanese model 94 Rav4.
There is something strange going on with the wires that were going into
the back of the previously installed head unit.

The plug on the back of the old unit wasn't the same as that on the new
(Panasonic) unit. So I cut the old plug off and installed push on
connectors on each of the wires.

I've found the gnd wire and the always on and on-with-ignition 12V
wires. But I am having trouble with the remaining 9 wires.

I tried connecting the output of one side of the head unit to every
combination of pairs of wires (I known not a good idea). That sometimes
resulted in sound at each of the speakers, but overlaid on top of that
was a heavy rumble of electrical engine noise.

On further investigation there was 5V present at 5 out of 9 of the
remaining wires. That left 4 wires with 0V present (as I would expect
for speaker wires) However as there are 4 speakers I should expect to
see 8 wires available. I tried outputting a signal between each wire and
earth, but that produced no result.

I also opened up the door panel and checked for continunity between the
speaker in the door and each of the wires. None of them showed a
connection.

So there is something strange going on with the speaker wiring. The old
radio (a Mitsu****a or something I think) worked fine (well for a Cr*ppy
old radio at least).

Anyone seen anything like this before?

Pete


--
Remove pants from email address to reply.

Yikes... stop everything and review a shop manual or do a little www
research before you fry something. Id hate to see you wire the 5V+
potential across the head units amp outputs.

I think they sell wire harness kits at Crutchfield. Those usually come
with a wire color code diagram.

Good Luck!!
Garrett

Peter Grooby wrote:
I am trying to install a new head unit in a japanese model 94 Rav4.
There is something strange going on with the wires that were going into
the back of the previously installed head unit.

The plug on the back of the old unit wasn't the same as that on the new
(Panasonic) unit. So I cut the old plug off and installed push on
connectors on each of the wires.

I've found the gnd wire and the always on and on-with-ignition 12V
wires. But I am having trouble with the remaining 9 wires.

I tried connecting the output of one side of the head unit to every
combination of pairs of wires (I known not a good idea). That sometimes
resulted in sound at each of the speakers, but overlaid on top of that
was a heavy rumble of electrical engine noise.

On further investigation there was 5V present at 5 out of 9 of the
remaining wires. That left 4 wires with 0V present (as I would expect
for speaker wires) However as there are 4 speakers I should expect to
see 8 wires available. I tried outputting a signal between each wire and
earth, but that produced no result.

I also opened up the door panel and checked for continunity between the
speaker in the door and each of the wires. None of them showed a
connection.

So there is something strange going on with the speaker wiring. The old
radio (a Mitsu****a or something I think) worked fine (well for a Cr*ppy
old radio at least).

Anyone seen anything like this before?

Pete

In article O0vbb.402589$Oz4.194756@rwcrnsc54,
says...
The only thing I can think of is there is a factory amplifier in the vehicle. Easy way to know is if there was only one plug behind the radio. Typically most US models of Toyota's will have two plugs for non-amplified systems and one for amplified systems.

It is possible I suppose. There was only one plug.

I tried hooking a signal generator putting out about a 6kHz signal to
every combination of pair of wires and didn't get any signal. I would
have expected to hear something even if there was an amp included.

Is it possible that the amp was expecting a remote signal from the tuner
to turn itself on?

There were a few mysterious metal boxes with wires coming out, under the
dash. But none that I noticed looked anything like an amp.

Are RAV4s/Toyotas with factory amps common? The stock stereo wasn't
particularly loud. Also it is hooked up to lousy paper speakers. Why
have an amp on crappy old speakers, that you could just run straight off
the head unit.

Thanks for the suggestion.

Pete
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In article , says...
Yikes... stop everything and review a shop manual or do a little www
research before you fry something. Id hate to see you wire the 5V+
potential across the head units amp outputs.
I agree with your sentiment. I've done some poking around online but
with not much success. I've read a bunch of pages on RAV4 head unit
installs and they all just do it by adding an adapter harness.

The wiring diagrams I've found. Are all for a two plug setup. I've only
got one plug. Also the wiring colours listed aren't anything like what I
am seeing. I suspect the problem may be exacerbated by by vehicle being
an ex-japanese model and all the websites being for US models.

Pete

I think they sell wire harness kits at Crutchfield. Those usually come
with a wire color code diagram.

--
--
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Interesting... as an ex-toyota manufacturing engineer I didnt think they
had completely different wire color schemes from Jap to US models. If
thats the case, I dont think the crutchfield kits would help much. I am
pretty sure they are for USA released vehicles only...

Might want to try and contact them with your unique situation.

Garrett

Peter Grooby wrote:
In article , says...

Yikes... stop everything and review a shop manual or do a little www
research before you fry something. Id hate to see you wire the 5V+
potential across the head units amp outputs.

I agree with your sentiment. I've done some poking around online but
with not much success. I've read a bunch of pages on RAV4 head unit
installs and they all just do it by adding an adapter harness.

The wiring diagrams I've found. Are all for a two plug setup. I've only
got one plug. Also the wiring colours listed aren't anything like what I
am seeing. I suspect the problem may be exacerbated by by vehicle being
an ex-japanese model and all the websites being for US models.

Pete

I think they sell wire harness kits at Crutchfield. Those usually come
with a wire color code diagram.

i can tell you right now as a professional installer (well certified at
least) that cutting the factory harness off was real dumb. you should've
made sure you couldnt find a factory adapter before doing that.. and another
thing, it was probly even dumber to start connecting random wires.

But i'm not one to put someone else down so i'm going to try to help you
here.

Obviously this particular vehicle has an external amplifer for the head
unit.. probly burried in the car somewhere.. these are usually not easily
by-passed with tearing things up in the car so i'd recommend you put the
factory harness back together by soldering and heat shrinking to make it
nice and tight again then i'd keep looking for a factory plug adapter

Just what i'd do.

DJ TecThreat

"Peter Grooby" wrote in message
.. .
I am trying to install a new head unit in a japanese model 94 Rav4.
There is something strange going on with the wires that were going into
the back of the previously installed head unit.

The plug on the back of the old unit wasn't the same as that on the new
(Panasonic) unit. So I cut the old plug off and installed push on
connectors on each of the wires.

I've found the gnd wire and the always on and on-with-ignition 12V
wires. But I am having trouble with the remaining 9 wires.

I tried connecting the output of one side of the head unit to every
combination of pairs of wires (I known not a good idea). That sometimes
resulted in sound at each of the speakers, but overlaid on top of that
was a heavy rumble of electrical engine noise.

On further investigation there was 5V present at 5 out of 9 of the
remaining wires. That left 4 wires with 0V present (as I would expect
for speaker wires) However as there are 4 speakers I should expect to
see 8 wires available. I tried outputting a signal between each wire and
earth, but that produced no result.

I also opened up the door panel and checked for continunity between the
speaker in the door and each of the wires. None of them showed a
connection.

So there is something strange going on with the speaker wiring. The old
radio (a Mitsu****a or something I think) worked fine (well for a Cr*ppy
old radio at least).

Anyone seen anything like this before?

Pete


--
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In article , "DJ TecThreat"
beaniATcharter.net says...
i can tell you right now as a professional installer (well certified at
least) that cutting the factory harness off was real dumb. you should've
made sure you couldnt find a factory adapter before doing that.. and another
thing, it was probly even dumber to start connecting random wires.

But i'm not one to put someone else down so i'm going to try to help you
here.

Obviously this particular vehicle has an external amplifer for the head
unit.. probly burried in the car somewhere.. these are usually not easily

My current thoughts are that if I can't find the amp easily, I'll just
run a new set of wires to each speaker, shouldn't be a big job
hopefully.

Pete

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