I have a 2002 RX300 and a week ago noticed some strange things happen - temp gauge not working, door locks not working on rear doors, rear windows not working, heat/fan/defrost not working, display blank except for clock and radio, daytime running lights not working, and occasionally A/T oil temp warning light or others come on temporarily. Battery was good, but installed a new one. Running charge of 14.2, so seems the alternator is working. If I disconnect the battery for a while or overnight, everything comes back to normal until the car is turned off and restarted - then things start not to work again. I am guessing that the battery disconnect affects a ECU reset, but something must be confusing it - a short somewhere? Anyone seen anything like this before? Any ideas? Thanks!

 

Was any electrical work done on the RX or any grounds disconnected.

Check your the terminals and posts ... you should not be able to spin the terminals. Also look at the clamp of the terminal for corrosion or loss of material. Follow the wires to see if the other end is loose.

Some things get reset on turning off the vehicle and almost all get reset by removing the battery power for about 20 mins.

Salim

 

So just like going to the doctor - or mechanic - as soon as I posted this the next day everything was fine and remained that way for 4 days. Then the symptoms started again - only driver window works, no heat/defrost/ac and blank display except for the clock. That way for a day, then fixed on it's own after 4 or 5 restarts. I will need to fix this before summer as I can stand the cold, but hate the heat. Sounds more like a short, but I have no idea where to start.

I know the battery is good, and have checked the ground, terminals, and verified the alternator is working (14.15 V)

 

There are multiple ground locations and one needs to know the history of the vehicle past work.

Random electrical problems are very hard to trace.

Going along with your analogy ... it will be a visit to a psychiatrist. Hope it gets diagnosed.

That is why before offering to help, I try to gather as much information I can,

Salim

 

I noticed a wet spot on the carpet by the driver's left foot which I though was from wet shoes. However, I found rainwater dripping from the emergency brake bracket but was unable to see much higher. But I did notice there is a large wiring loom above the bracket that I fear is getting wet and causing the short. We had a nice long dry spell and the electronics have been behaving normally. Now I am trying to source the leak(s). As long as the weather is dry I will be fine apparently. Thankfully summer is on the way. By fall I will need to find the leak or get rid of the car. Or move to Arizona...

 

Mark the position of the wipers and then remove them. [I have instructions in knock sensor DIY]
Open hood and remove the cowl. Examine where and how the rain water runs off.


The other source would be the missing/borken/cracked plastic shield in the wheel well.


Salim

 

Thank you Salem for pointing this out - I also have a vintage 02 RX 300 with the rain water puddling by driver left foot and electrical gremlins

 

My 2002 RX300 just went dead last night. No power at all - nothing. I went in my house about 5 minutes later and retrieved a different key FOB and tried it. My car responded to it and the power came on again. I drove the car to the store and it worked fine. Today, I went to go somewhere and guess what. Same thing happened, but this time neither key FOB did anything. Car is sitting in the driveway waiting for me to try another battery. Weird thing is, last night when the car came back to life, the battery seemed strong, like new.

 

The immobilizer in the fob does not control all things electric in the car. Just the security system that prevents the engine from starting.
Check your battery connections

 

Can you please elaborate on "No power at all - nothing". I am sure it is crystal clear in your mind but details like ... door-lock/unlock with key fob, physical key only opens driver door, dome light coming on when the door opens, brake lights in the back come on, horn operates, head light come on, dash lights up etc can help some preliminary diagnosis.

It could be that your situation is that you could only lock unlock with the physical key [and no other locks open with double action] then the 12v battery source is not getting through. Since it cam back alive and sustained good current, indicates potential loose terminal at the battery which can arc closed and then open. If your instrument cluster did light up through out then the problem can be in the starter.

In either case a new 12v battery will not solve your problems [exception being tightening of the post after the install of battery].

Salim