Help Needed, Aftermarket Headunit Install, So Confused.

[Dean1309]

Hi Guys,

I am thinking of purchasing a double DIN DVD headunit very soon. I have no problems in understanding how to go about fitting the stereo. That part is easy.

What I'm really confused on is the speaker / amp wiring. Do you guys that have changed the headunits, change the rear speakers as well? My understanding is that a aftermarket headunit powers speakers at 4ohms. However the Lexus rear speakers are running at 2 ohms via the amp. The lexus rear speakers are two individual speakers (speaker and woofer) in one 6x9 speaker.

Now surely a 2 ohm speaker running from a 4ohm headunit will damage the headunit. If im spending £500 ish on a DVD headunits thats the last thing I want.

I have read that you can remove the loop on the bypass cable to only feed to the rear speaker and not the woofer. Which I thought about doing but surely the speaker as a whole is still running at 2 ohms.

I've seen its been done and really want to do this but do not want to damage either the lexus speakers or the new headunit that I am about to purchase.

Any advice would be much appreciated as I am so confused regarding the whole issue of Lexus amp / Speakers.

Thanks,

Dean

[steve2006]

I could be wrong here but someone will correct me I'm sure but IIRC you lose the sub with an aftermarket system as the bypass doesn't accomodate it.

I'm a glutton for punishment but an electrical engineer so hardwired my LS400 system but also fitted a seperate sub amp supplied by one of the headunits low level phone outputs to power the speaker and yes they are 2 Ohms ( the sub amp I bought was selectable impedence so no problem)

Also running a 4 Ohm impedence output into a 2 Ohm impedence speaker will damage the amplifier and/or speaker as it will draw twice as much current. Twice the current= twice the heat= amplifier/speaker demise.

[Dean1309]

So if im reading that correctly when I connect the bypass cable to the amp and new headunit. I will lose the woofer, if that is the case then its not so bad as I have a sub and amplifier in the boot.

On the over hand, from the last statement you wrote saying about running 4 ohm impedence into a 2 ohm speaker will damage the amp and/or speakers, does that mean that rear speakers would have to replaced to avoid any damage?

How many people on this forum who have fitted these DVD headunits have actually replaced the rear speakers? From what I've read, (if im wrong im sure I would be corrected), people just remove the old Lexus stereo, run the bypass cable and install the new headunit. Is it safe to do this?

[IHgs300]

When i wired mine, i used pre amp out puts on new stereo and connected to oem amp with rca plugs. Saved messing about with by-pass cables ect.

[Dean1309]

Might have to give that one a go, I have never actually seen the amp in my car, I know its behind the glove box and know I can see a part of the amp when glove box is open but have no idea what plugs are on it.

[IHgs300]

if you need the wiring diagrams i have them.

[Dean1309]

If you have them then that would be great mate, would be much appreciated :)

[Dean1309]

Have just come across a picture of the standard rear speakers for the Lexus. The speaker states the speaker is 4ohms and the woofer is 2 ohms.

Would it then be ok to keep the standard rear speakers, if the bypass cable to no longer outputs the signal to the woofer. As you are matching the head unit amplifer 4ohms with the speaker output of 4 ohms.

[IHgs300]

Here you go

http://www.4shared.com/rar/JKVj8UD9/lexus_wiring_diagrams.html?

[IHgs300]

Just thought i have some standard speakers out of the s model, which are single speakers and will def be ok if you want to put your mind at rest.

£17 posted due to weight.

[dkdk]

Hi guys

new to the forum so not really sure if im in the right place but need a little help from you........

I have a 2001 is200se with factory nav, cd player gone wrong and shows error1 and wont play discs, wanting to just replace the headunit for one I have lay around, aftermarket stereo stuff I know very well been doing sound off's in my younger years but this wiring and factory amp has me beat, I know I need a bypass cable which easily had from eBay but confused as to what of my sat nav I will lose, I dont mind loosing the voice as I never use it anyway ( easier to use Iphone using postcode ) but confused if I will lose the operation of the screen !!!!!!!!.

really hope someone has the answers I need searched everywhere online but no-one really mentiones the factory sat nav.

cheers :-)

[IHgs300]

Hi guys

new to the forum so not really sure if im in the right place but need a little help from you........

I have a 2001 is200se with factory nav, cd player gone wrong and shows error1 and wont play discs, wanting to just replace the headunit for one I have lay around, aftermarket stereo stuff I know very well been doing sound off's in my younger years but this wiring and factory amp has me beat, I know I need a bypass cable which easily had from ebay but confused as to what of my sat nav I will lose, I dont mind loosing the voice as I never use it anyway ( easier to use iphone using postcode ) but confused if I will lose the operation of the screen !!!!!!!!.

really hope someone has the answers I need searched everywhere online but no-one really mentiones the factory sat nav.

cheers :-)

Send a pm to this member he did a fix for the sat nav without headunit.

http://www.lexusownersclub.co.uk/forum/topic/74064-is200-oem-sat-nav-fix-kit/