2008 RX400h aux audio install

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I have searched the forum, but most vaguely relevant threads are years out of date.

My car is a Lexus RX400h 2008, Mark Levinson sound system.

I bought a generic Bluetooth, usb, 3.5, adaptor. I also bought a Y splitter. I installed everything and the Bluetooth worked just fine. Didn't actually try usb etc.

Then I connected the existing connection, which I now know includes air con at least. The outcome is that I cannot connect both. One or other work if connected alone, but connect both and the Bluetooth doesn't work.

My previous research suggested it was just the CD changer that would be affected, something I could live without, but air conditioning is another thing. The screen goes blank and tells me the 'system' is not connected.

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Item Sku Qty Subtotal
Toyota / Lexus (recent) - USB3 Iphone Android integration kit
Vehicle Specific Cable
Connection to back of radio on select Lexus models - LEX
Bluetooth Dongle - £38.00, 3.5mm Aux-input cable - £10.00
Subtotal £131.65
Shipping & Handling £5.99
Grand Total (Excl.Tax) £137.64
Tax £26.33
Grand Total (Incl.Tax) £163.97

Instructions to courier: 2008 RX400h


from grom audio

It works grand.

I use podcasts on my phone through Bluetooth and they auto start when I connect to the grom.

It was simple to install just removing the 4 screws on the ML head unit and plugging in the adaptor.

The USB songs show up on the existing display but can take up to 30 seconds to show up. Could be the songs  metadata, Doesn't bother me.

Never used the aux but the socket is there.

when a call comes in it uses the existing lexus Bluetooth which means all the steering wheel buttons work as expected, and the grom knows to pause.

The Grom + Bluetooth unit + Aux fit nicely under the ML Head unit. I brought the USB over to beside the Boot opener switch and took out one of the blanks.

The Grom didn't effect my air con

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Thanks for that!

Seems to be the same course I have just followed. The Grom wiring works (though I only just got it working late yesterday). There were a few lessons learned about the need to power off properly.

I actually then refitted the non working system to see if this worked in the light of my new findings. Nope.

Currently I only have a USB connection, which seems adequate. Good point you make about the existing phone Bluetooth covering calls.

I haven't yet tried to access the screen menu (mainly because I was unaware of it). So far my concern is that my phone sat nav seems to mute the music ok, but there is no voice? Perhaps that is in the hidden settings?

I did read some references  about fitting a 68ohm resistor between two wires? A bit beyond my confidence levels.

Question, what mic (if any) does the existing Bluetooth use? Is this built in to the car?


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yes  I believe the existing mic is up behind the mirror.

I think the Grom mic is only used for voice to txt on the phone, where the lexus mic is used for the voice commands on the rx.

The screen menu came with a grom update about 18 months ago.

I use the grom Bluetooth is  used for streaming .

Odd though Navigator satnav for android plays the voice through all the speakers and pauses the stream, but as far as I remember Google maps for android just comes out of the Front Right speaker.  Both 

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I haven't (as yet) got the Bluetooth kit, it has already proved to be an expensive hobby. (Having bought another Bluetooth kit previously)

As things are I'm not sure I need that. The USB connection does the job just fine, with the built in BT dealing with the phone separately. I don't get any menu screen at all. 


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