As a point of reference, my LX is an '01, and doesn't have an integrated back-up camera. I'm in the process of adding one with the NAVRGB 2.0 or some version of homebrew, but noticed a few wires specifically while researching and looking at the factory wiring diagram.
First, does anyone have any clue what the Red with Black Striped wire labeled "From Back-up Light Sw [Park Neutral Position Sw]" in the factory wiring diagram is actually used for? The wire is part of the larger 18-pin connector (N2) on the Navigation ECU? At first I was curious if it has to do with allowing access to punch in addresses while moving. But I test drove this configuration with the wire removed from the connector, and the system still locked you out.
Next, since that test drive failed, I'm now interested in removing the speed wire, as I'm not sure what they's use that for on the NAV system since it inherently gathers speed data. I'd imagine the developers could quite easily grab the speed data from the GPS process; afterall that is a major function of this ECU. That said, does anyone know for sure what else the speed wire to the NAV ECU could be used for? I'm willing to bet the signal is a proportional voltage signal similar to spinning a potentiomter to vary voltage. This same speed signal is split and also sent to the Multi-Function Display, and to the amplifier. I suspect the speed signal sent to the amplifier is used for the ASL, or whatever Lexus calls the automatic volume control. Then I suspect the signal is used to lock you out of the DVD in motion, when using the changer as the video source.
I'm not really searching for the holy grail "OK" button bypass at startup, but I am searching for the ability to have passenger enter addresses while in motion. My TL allows this, and we use it all the time.
Anyway, as mentioned above, I ran through the following sequence to determine voltage on the Back-up wire I mentioned up top:
(All with voltages checked Ignition ON)
In Park (no brake pedal): 1.5 to 2.6mV, Essentially 0V
In Park (with brake pedal): 250mV
In Reverse: 10.66V, Essentially 12V
Didn't test with brake, assumed didn't matter to signal
In Neutral (no brake pedal): 1.5 to 2.0mV, Again Essentially 0V
In Neutral (with brake pedal): 250mV
In Drive (no brake pedal): 3.0mV
In Drive (with brake pedal): 250mV
Interestingly, I found the console mounted DVD changer did NOT work once the Nav ECU was disconnected and the ignition turned on. I wouldn't have noticed this other than my wife must have been using it when she last used the car. Studying the wiring diagram, this is something that baffles me unless it is part of a digital control signal from the NAV ECU to the Radio. I don't see anything else other than the Amp Mute signal, but I know that isn't it because the FM part of the radio still works with the NAC ECU disconnected. I don't really care about this function, but found it strangely interesting. After turning the car back off, and making my way back to the rear passenger door to reconnect the NAV ECU, I heard the changer running through the 6 discs as soon as I plugged in the ECU again, which reinforces it not being a mute signal.
Sorry for this being so long. Hopefully over the weekend, I'll have to remove the speed signal from the NAV ECU. I'll report back.
First, does anyone have any clue what the Red with Black Striped wire labeled "From Back-up Light Sw [Park Neutral Position Sw]" in the factory wiring diagram is actually used for? The wire is part of the larger 18-pin connector (N2) on the Navigation ECU? At first I was curious if it has to do with allowing access to punch in addresses while moving. But I test drove this configuration with the wire removed from the connector, and the system still locked you out.
Next, since that test drive failed, I'm now interested in removing the speed wire, as I'm not sure what they's use that for on the NAV system since it inherently gathers speed data. I'd imagine the developers could quite easily grab the speed data from the GPS process; afterall that is a major function of this ECU. That said, does anyone know for sure what else the speed wire to the NAV ECU could be used for? I'm willing to bet the signal is a proportional voltage signal similar to spinning a potentiomter to vary voltage. This same speed signal is split and also sent to the Multi-Function Display, and to the amplifier. I suspect the speed signal sent to the amplifier is used for the ASL, or whatever Lexus calls the automatic volume control. Then I suspect the signal is used to lock you out of the DVD in motion, when using the changer as the video source.
I'm not really searching for the holy grail "OK" button bypass at startup, but I am searching for the ability to have passenger enter addresses while in motion. My TL allows this, and we use it all the time.
Anyway, as mentioned above, I ran through the following sequence to determine voltage on the Back-up wire I mentioned up top:
(All with voltages checked Ignition ON)
In Park (no brake pedal): 1.5 to 2.6mV, Essentially 0V
In Park (with brake pedal): 250mV
In Reverse: 10.66V, Essentially 12V
Didn't test with brake, assumed didn't matter to signal
In Neutral (no brake pedal): 1.5 to 2.0mV, Again Essentially 0V
In Neutral (with brake pedal): 250mV
In Drive (no brake pedal): 3.0mV
In Drive (with brake pedal): 250mV
Interestingly, I found the console mounted DVD changer did NOT work once the Nav ECU was disconnected and the ignition turned on. I wouldn't have noticed this other than my wife must have been using it when she last used the car. Studying the wiring diagram, this is something that baffles me unless it is part of a digital control signal from the NAV ECU to the Radio. I don't see anything else other than the Amp Mute signal, but I know that isn't it because the FM part of the radio still works with the NAC ECU disconnected. I don't really care about this function, but found it strangely interesting. After turning the car back off, and making my way back to the rear passenger door to reconnect the NAV ECU, I heard the changer running through the 6 discs as soon as I plugged in the ECU again, which reinforces it not being a mute signal.
Sorry for this being so long. Hopefully over the weekend, I'll have to remove the speed signal from the NAV ECU. I'll report back.
