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I have the 2014 CT200h, without the nav system. Didn't buy it because it was $4K more expensive and didn't like the idea of using a mouse to control it. That said, I immediately went to a car stereo shop and had them install a Kenwood DDX8901HD with a back-up camera. The device is pretty awesome. It improved the sound in the car tremendously, but there are some complaints I had - like how changing from bluetooth to HD Radio works, but that's another story.

About 4 days after the installation, my Tire Pressure (TPMS) light turns on, and stayed on. I took the car to the dealership where they spent most of the day checking the tires and replacing sensors. At the end of the day, they call me and they say the issue was with the aftermarket stereo blocking the TPMS sensor signal.

I took the car back to the stereo place. They looked at the wiring on the Kenwood and couldn't get the light to go off. They put the factory stereo back in, and the light stayed on.

I took the car back to Lexus, and they just reinitialized it, and the light went off.

I've now had a different stereo installed (Pioneer AVH-X5600BHS), and after a couple days, the TPMS light came back on.

Has anyone faced this issue? Were you able to install an aftermarket stereo without the TPMS light flashing?

Based on some other forums here, it seems the TPMS light isn't critical (and standalone). I plan on installing the Kenwood back in the car and either just resetting the sensor myself, or putting black tape over the light.

Thanks,
Luis
 

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It would never occur to me that an aftermarket stereo would do this. Maybe Toyota is on to something when they won't change anything remotely electrical on the car under the excuse that it might void the factory warranty. With some dealers I have known, you would never have gotten the service you have already gotten.

I hope you can get to the bottom of this. Must be very frustrating.
 

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Off topic, but would you mind posting a picture of the kenwood unit in your dash? I'm in the market for an aftermarket system and may consider this unit. Thanks.
 

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This is strange, it seems any experienced radio techs could fix this.
The issue is it seems is the factory wires was a relay on the canbus wire for the car.
I found this reference for the wiring for a ct, but no picture; lexus ct200h wiring

Basically the "canbus" communication in your car is voltage pulses on a single wire that goes in series to the sensors in your car. They basically all talk on the same wire. When you removed the factory radio, you broke that wire and now the communication does not make it back to your cars computer.
I have no experience with canbus, but I do serial communications for control systems.

The wiring list has listed a "Data bus" wires on the black 14 pin plug, pins 10 and 9.
"Canbus High" (3.75v signal) wired on the white 16 pin plug, pin 6.
"Canbus Low" (1.5v signal) wired on the white 16 pin plug, pin 14.

I would think all they have to do is connect each canbus wire that used to go through the factory radio to their other proper ends to complete the loop between the tpms and the cars computer. This way the cars computer will receive the communication signals from the tmps again.

You can buy canbus bypass kits for many cars for installing an aftermarket radio that just connects the canbus wires back together. I dont see any for the CT. A real radio install shop can figure this out and do this for you.
Either way the shop must fix this as part of the installation, but it does sound like you went to some very inexperienced people and they have no idea what they are doing.

There also could be more sensors on that wiring loop than just the tpms sensors that are now not communicating with the cars computer. I would not leave it disconnected unless you can verify that only the tpms is affected and you dont care about that.
 

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Discussion Starter #5
Appreciate the response. I plan on taking my car to a different shop and pass along this information.
Thanks again.
 

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Discussion Starter #8
I don't have the receipt, but I think labor was about $350, which included installing a rear-view camera. They weren't able to wire the steering wheel controls because a harness wasn't available. USB connectivity was also lost.
 

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To isolate, remove any cell phone chargers, pull the fuse powering the radio. Perform TPMS retrain. If it is sucessful, either a cell charger or the radio is at fault. Radios have oscillators that beat the incoming AM/FM signals to reduce them to our audible range. These oscillators and their harmonic frequencies can interfere with the TPMS system. Harmonics can be 162.5 mhz, 325 mhz, 650 mhz, etc. TPMS operates at 325 mhz. Aftermarket installations may not be compatible with factory installed equipment.
 
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