Lexus CT200h Forums banner
1 - 10 of 10 Posts

2012 Premium with Nav
18 Posts
Discussion Starter · #1 · (Edited)
Hello all

My 2012 CT200h with Navigation has a radio issue. I've replaced it twice, but still no dice. Here are the symptoms:

What works
-The navigation screen flips up and stays on the map view when the car is on
-Back up camera works
-Mouse centers when the car is turned on or off
-Radio lights work and dim accordingly
-USB does charge my phone, but painfully slow (1% per 10 min). My phone does stop playing audio aloud when its plugged in, suggesting the USB port does behave like a receiver
-When I press the phone call buttons on the steering wheel the nav screen switches to a call screen with a num pad.
-When I press the SOS button on the ceiling the warning comes on that my subscription is up. This is the only noise the speakers make

What doesnt work
-Anything that a standard radio would do
-Anything in the infotainment center
-The whole system is effectively dead besides the back up cam and nav screen

What I've tried
-Checked, sanded, and ran continuity tests on the following fuses:
  • Rad 1 under the hood
  • S Horn under the hood
  • Amp 1 and 2 under the hood
  • Rad 2 under dash
  • Panels under dash
  • Meters under dash
  • Power Outlet under dash
-Checked impedance of all speakers at the amplifier connection under the seat. See the break down section below.
-Tapped each speaker from the amp connections with a 9 v battery, all made noises.
-Checked to make sure the amp has sufficient power and ground. (note they were 14V+ while the car was running and only 12V+ when turned off)
-Replaced the radio with two different used ones that supposedly worked
-Pressed and held the power button for 15 seconds
-disconnected the 12V battery for 20 min

Impedance and Voltage Checks
H57 Connector at Amplifier:
Rear Left Door (Pin 4 to 11): 3.2 ohm
Rear Right Door (Pin 5 to 12): 3 ohm
Front Right Door (Pin 9 to 10): 3 ohm
Front Left Door (Pin 3 to 8): 3.2 ohm

H58 Connector at Amplifier:
Woofer (Pin 1 to 2): 1.4 ohm
Front Left Dash (Pin 3 to 9): 3.3 ohm
Front Right Dash (Pin 4 to 10): 3.7 ohm
Front Center Dash (Pin 8 to 7): 3.4 ohm

H56 Connector at Amplifier: (Checked for voltage using pin 5 'Body Ground')
Vehicle Speed Signal (Pin 2): 14.3V
MOST Communication Wake-up Signal (Pin 3): 14.7V
MOST Communication Signal (Pin 4): 0
MOST Communication Signal (Pin 6): 0
MOST Communication Wake-up Signal (Pin 9): 0
MOST Communication Signal (Pin 10): 0
MOST Communication Signal (Pin 12): 0

H59 Connector at Amplifier:
Power Source (Pin 1 to 2): 14.9V when car is running, ~12V when car is off
Power Source (Pin 3 to 6): 14.9V when car is running, ~12V when car is off

Connectors at radio:
Soon to come

Additional Information
-The used radios I installed did not work, however I could hear noises coming from the disk changer for a couple of seconds when the car was turned on or after replacing the fuse.
-I bought the car like this, never heard the speakers work.
-The faceplate number is P10041

My plan
-bench test spare radios
-I have a third radio I will be installing soon.

If anyone can help or has information please share!

2012 Premium with Nav
18 Posts
Discussion Starter · #3 ·
I think my problem may be similar to the unanswered thread here: 2012 CT200h w/ nav - AMP reprogramming?
I will reach out to the poster. After digging around other Lexus forums, it may be possible the head unit is going into a protection mode, which would fit with the units only making sounds from the CD player when newly installed.

46 Posts
I have a simple fix for a similar problem here:
But considering you had tried disconnecting the battery, I think it is unlikely that my fuse pulling fix would work, but heck, give it a try.

4 Posts
Hello everyone,

I brought my car to a carwash the other day and now I have the exact same problem! I've tried everything mentioned by you in your posts but my Radio is still not working. The behavior is exactly as you describe it.

Navigation starts by default but Mouse and Radio buttons are not working. Steering wheel phone button opens the dial-pad but can't do anything.

When you refer on cleaning the fuse contacts, which fuse you are referring to?

I've tried this - which it does restart the media: show HDD Loading screen

RAD №1 - 15A - Audio system, navigation system
But still no results 😭😭😭

Is there anything else I can try?

Please help me!

4 Posts
Thanks for your reply Shobhus20!
I wonder how the Amp can get bad after just a Car Wash - no fuse to protect it!

If the Amp would be the problem, why the mouse is not working anymore?

Should I try an independent service or Lexus dealership will be the only option?

I'm so confused... and I really want it to be fixed!

3 Posts
Hi 👋 Even I was thinking that the head unit is the issue but after troubleshooting I got to know it’s the amplifier. Amp has a lot of control over the music system. usually Amp gets short circuit in the electronics board may be because of water I’m not sure. Lexus dealership will cost you a lot. Better get it repaired in local audio shops. Good luck mate.

4 Posts
Thanks, I need some luck here! Hopefully I'll be able to find a reasonable $ option! I'll get quotes from both, just hope to be fixable since my CT is from 2011... pretty old, but still running fine and only 130k km odo...
1 - 10 of 10 Posts