While waiting for the engine parts to come in, started to look at the Navi issue i have. It pretty much does not work at all. Before i had an issue with illumination, that was fixed by changing the drivers side ECU in the foot well. Now all is fine, including gearshift bulb, radio, steering wheel control lights and everything that still has the bulb intact. Radio CD changer was fixed as well - that got CD broken in pieces in it, that jammed the mechanism. So i cleaned this up, realign it and it works fine now. I am waiting for the 68Ohm resistor to come in to try that trick to short the wires in the radio, and see if it will work, to eliminate the radio from the chain, even though the radio itself seems to be working fine.
Symptoms:
When ignition is turned on, screen momentarily shows very dim LEXUS logo and then nothing, although looks like the screen itself is powered up, kinda like a broken LCD screen with dark screen outline. The whole unit was changed to the presumably working one, same effect.
DVD in trunk - can eject it, unit was changed to the presumably working Gen4 dvd, same effect.
AC control - the only thing that i can do with controls is to press TILT, and the screen moves in an out (but not to the point of when you can close the door). control was, again, changed to possibly working one, same effect.
When Navi was disassembled and i manually closed the door, after unit was installed back, door opened by itself i think, after that, same symptoms. All motors work fine when 12V applied.
Things i didnt check:
1. I didnt change the radio, will do the resistor trick to see if this is the culprit
2. When Techstream is connected, there is a function Can bus check - this does NOT work, although everything else looks fine in the app. Since it is 2003, it has BEAN bus, is there a way to tap into that? And as a general question, will anything show whats going on on the bus and how all the devices are communicating?
3. Steering wheel controls do not work, i did the reset, still no go. i think i will take the clock spring off and check the cable. That should not really interfere with navi though..Interestingly enough the switch does have blue and white buttons for phone and voice control under cover, i thought voice was the option for the later models? i wonder what will happen if i use that after i fix the connection

 

by the numbers:
1. I don't know, but doubt the resistor trick will work if the radio works. I say that as the radio commands the nav door, amplifier though the bus and that resistance tells the other devices that the radio is the bus master. So, if the radio can control volume, I believe the resistor is still in circuit.
2. I have never heard of anything to check the BEAN Bus, but the radio has some kind of built-in diagnostics with a specific key press routine, and then it will display trouble codes. I don't know how to do that as all my audio was DOA when I got the car. I'll look around and see what I can find. You could go on the Toyota/Lexus site: techinfo.toyota.com , pay them a few bucks and download pdf files for a day or two. That would give you lots of info on multiple areas.
3. 2002 doesn't have those buttons, I'm no help whatsoever.

 

I took out the clock spring and checked connections, all is fine, so it is not it. This is part of the bus and goes into the radio as i understand it, so maybe somethis is broken inside..dunno, ill do resistor thing to eliminate the radio completely

 

As you said - resistor trick did not work and now tilt stopped working as well probably a fuse since i was unplugging/plugging it live..anyways, i dont care much about the navi itself, probably will be replacing it, but i'd like to retain the door open/close.
So what next? anyone powered up the navi unit on the bench? On the schematics these are +B1 and ACC or i have to feed +12V to ST1/+B1 and IG?
ST1 has to be powered only while starting the engine as i figured? The power goes into the plug, also there is a green wire on the pin 2 with 4 volts on it.
it gets 14.5V instead of 12V, is this normal? i think navi unit is shot, even though i tried another one and it behaved the same..

 

I just realized that techstream apparently has a function to check the steering wheel controls. They all work, but still do not control the radio. Also since navi TILT function stopped working as well, in addition to all my problems, im thinking to replace the gateway ecu and see what happens. Also i cant find steering wheel controls anywhere on schematics, but still i think this part and navi is a separate circuit on this ecu, so maybe this was shot...

 

Not sure on your year, but for 2002 the Gateway handles that and more (like TPMS, transponder key computer, interface to OBDII port, etc.). I haven't run down all Gateway functions. I frequently misunderstand schematics, but replacing the Gateway may impact your keys.

The audio control buttons, the horn and cruise control all go into a 6-pin connection next to the airbag connector on the spiral cable side of the steering wheel. In addition to airbag control, coming out of the steering wheel are a couple of connectors (C10 and C11). Wire in C10 sends signals to the Gateway ECU, and the Gateway ECU talks to the radio. The radio is the LAN master for audio, Nav and the amplifier. C10 also handles the Cruise Control interface to the engine control module. C10 also handles the horn (I think mostly for the security system) through the driver's side junction block ECU. Finally, C10 also has some connection to the telephone computer (per wiring diagram, don't know if 2002 actually had a phone option for USA models). C11 handles the tilt & telescope function of the steering wheel. Not sure what else. I have yet to take off the steering wheel to trace out wires. I can say with certainty that the color of wires coming out of the audio control pod on the side of the steering wheel do not match the colors coming out the other side of the wheel at C10.

Hope that helps you think through your issues.

 

Well, i hope this will help someone in the future - i bought a replacement gateway ECU and in preparation for the replacement got to the old one, plug was there a bit loose or so i thought, maybe just my imagination, Nevertheless i unplugged it and plugged it back in till i heard the click, and low and behold - navigation works, steering wheel button work, all is back to normal. So all the symptoms were really untraceable and car was fine, radio was working, dvd could be removed, pretty much all were intact, except navi and steering wheel controls. If yours behave the same - try this gateway ecu plug or get a new ecu...

 

Ah hah, congrats and thank you for sharing this. I’ll save this post.

 

Btw i think i know why this happened, i was checking service records on carfax and lexus and saw that the drivers air bag was changed, so i think whoever did that, did not connect this back properly or dislodged the plug