Hello everyone,

I recently bought a 2000 Lexus RX300 from Florida. It had roughly 99k miles when I bought it and now it just broke 100K driving it back up to Michigan. There are a few issues associated with it when I bought the car. First, the display screen is blank, the radio/climate control all work but I cannot see what station I am on or the temperature. The display lights up but that is about it. Second, the power door locks do not work for any of the doors and neither does the key-less entry system. I have to manually open and close the doors either by key or the inside switches. Also when you open a door, the courtesy door lights light up but the dome lights do not as well as the foot lights do not light up as well. Third, the fog lights do not work as well as the rear wiper. (The wiper fluid motor does work in the back and wiper fluid does come out.) I noticed the rear antenna was also broken off but I can hear the motor running when the radio is turned on/off but just for 15 seconds or so. Besides that, the car runs pretty good. I have checked and double checked all fuses in the engine compartment and driver foot well and they all seem to be fine. I have checked the battery and alternator and they seem fine as well. When fully charged, the battery gives off roughly 12.6 volts and when charging it is around 14.2 volts. When the car is running, it is around 13.6 volts. Now, if the car sits for a day, I've noticed the battery drops to about 11.67 volts. If it sits longer, it drops even lower. It seems like I have a short or something within the system. So I unplugged the negative terminal and hooked up a multi-meter to see the draw. I closed all doors (turned off all lights and accessories) and set a screwdriver in the hood latch to make it though it is closed. I set the multi-meter to DC 10A and I got about .50 Amp draw with everything off. I took out the DOME fuse and it went down to .30 Amp draw. When I took out the ECU-B fuse, it went down to about .001 Amp draw (Including the DOME fuse out). Currently I am stuck as I tried replacing the display with other displays but it did not help. I also have a donor antenna from a vehicle in the truck that I have not set up yet. Can you guys shed any insight into my problems as I am not to electrically savvy as I'd like to be lol. I am pretty good on the mechanical side though.

 

With all the electronic issues, do you see any indication that the RX was flooded at some point?

 

I did not see any indication that it might have been in a flood. When I opened the rear hatched to check the spare tire, everything looked completely new and the tire or jack as never been touched before. The previous owner was an elderly man apparently. What I did notice though when driving the car back was a small drop of water on my right foot when it was raining on the highway. I checked up the driver steering column to see if there was any corrosion but everything seemed fine. Come to think about it, the headliner does seem to have a bit of discoloration in certain areas as if water did leak a bit from the outside. I am doing a junkyard run coming up this weekend and I was wondering if I can get the BCM under the dash would it be just a plug in if the codes match? I know the ECM needs to have the mastery key with it in order to start the car and reprogram everything and that is almost impossible to find at junkyards. Thanks for the quick response Dave!

 

Get hold of circuit diagram and start tracing. Dead is easier to trace than intermittent.

If you the nw ECU route, try to get the key cylinders along with the master keys.

Salim

 

So I started to take apart some panels and such to find some issues. I've noticed that the rear hatch had paint over the wiring harnesses and then compared the vins to see if they are the same. It seems that the hatch is from a different car. I tried to check the wires for bad grounds but could not find any. Then I saw that a fellow member of this site had issues with the rear door ECU's so I disconnected them and checked the voltage. With both of them disconnected, the ECU-B fuse went down to about 1.0 from the original 2.2 millivolts but the DOME fuse went up from 1.7 to 2.3 ish. Do you guys think that may be a culprit of this since when I disconnected the rear door ECU's the door ajar light stayed light on the dash as well? I checked for some wiring diagrams but did not find any yet.