Hey guys. I've been having some trouble with my 02 430, and was hoping someone could provide some insight.

I have an error message on the nav screen that says "Check connection of the air conditioner." At the exact same time this error started, the audio controls on my steering wheel stopped working. I can still use all of the buttons on and around the screen to use the radio/cd, but the air conditioner buttons and the the climate button are unresponsive. I've also noticed that when I press the FM button to switch between modes, I only have FM 1 and FM 2. There used to be a third option, FM Type. My stations also do not display the song names anymore. Instead, it drags and shows the name of a song that was on weeks ago. I thought it was only because I was in a rural area, but it's the same if I go into nearby metro areas. Also, the A/C is blowing cool (not cold) from the driver's side vents, but hot from the passenger vents. I had the entire system replaced last year, and it has only recently started acting up.

Based on my searches here, I'm hoping that the culprit is the Gateway ECU. I took the car to Lexus, who has been completely unreliable in the past, and they told me that the problem is the entire navigation unit. I was told that the unit controls the a/c, steering wheel audio switches, and fm settings.

Any suggestions on which is the culprit?