Question for the group…I have a 2000 LX470 and the air conditioning, radio, lights behind the dash (lights on gauge needles work though) and lights on hvac unit (buttons still work) and directional adjustment to mirrors are not working all of a sudden. I had alternator changed out and had to jump the car a couple times, and after I brought it home that’s when I noticed this all. Any suggestions? I’ve replaced all the fuses related to these items in the fuse box in the driver side floorboard area.
Help with electrical issues on 2000 Lexus LX470
- Thread starter tnmudrunner
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Malleus
Far west of Siegen
Do you have the FSM & EWD?
- Thread starter
- #3
No I do not.
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- #4
Malleus
Far west of Siegen
You can download them for free from the Resources section. That's the place to start.
Disconnect negative terminal for a few minutes 
♂
♂
Malleus
Far west of Siegen
The reason I ask is that the NAV unit integration in the 100s seriously sucks. There is, literally, 100 pages of troubleshooting procedure for it in the FSM.
The solution may be easy, or it may require a lot of investigation. The good news is that all it will cost you, initially, is your time. And, you'll learn a lot about your truck in the process. I'll be glad to give you whatever help I can, and there are others here who will chime in happily.
I assume you're the kind of person who's interested in this, or you wouldn't be here. If you're not, your options are really limited to finding someone else who will do the troubleshooting for you (good luck with that), and hope they don't take you for a house payment (or two) in the process.
The solution may be easy, or it may require a lot of investigation. The good news is that all it will cost you, initially, is your time. And, you'll learn a lot about your truck in the process. I'll be glad to give you whatever help I can, and there are others here who will chime in happily.
I assume you're the kind of person who's interested in this, or you wouldn't be here. If you're not, your options are really limited to finding someone else who will do the troubleshooting for you (good luck with that), and hope they don't take you for a house payment (or two) in the process.
Malleus
Far west of Siegen
Whenever you experience a multiplicity of failures, that are apparently unrelated to each other, after a single event (like replacing a component), it's easy to assume it must be something related to that event that caused all the failures. Sometimes it is, but it's just a s likely that you just experience age related failures at the same time. I have a 2000 LX470 in the driveway that has this condition.
The best, most efficient, troubleshooting plan is to start with the simplest component/system that has failed and try to determine what happened to it. Often, you'll find the root cause for the other failures when you solve this problem. In your case, I'd suggest starting with the mirror switch:
Start with any error codes; the troubleshooting guide (DI section) will walk you through what to do with them. If you have no error codes, the fix should be something simple, like a plug that isn't plugged into something (although, this may lead to an error code, too).
Here's the mirror FSM section (BE-132 through BE-138), while you digesting the FSM/EWD you downloaded.
The best, most efficient, troubleshooting plan is to start with the simplest component/system that has failed and try to determine what happened to it. Often, you'll find the root cause for the other failures when you solve this problem. In your case, I'd suggest starting with the mirror switch:
Start with any error codes; the troubleshooting guide (DI section) will walk you through what to do with them. If you have no error codes, the fix should be something simple, like a plug that isn't plugged into something (although, this may lead to an error code, too).
Here's the mirror FSM section (BE-132 through BE-138), while you digesting the FSM/EWD you downloaded.
Malleus
Far west of Siegen
Just so you know, the concern with the 100 and later trucks is that Toyota, in its infinite wisdom, decide to design a communication bus into the electrical system. This means that the multiple ECUs in the system need the communication system, as well as their sensors and internal gizmos, in order to make the truck work. Troubleshooting isn't hard, it's still a very simple telephone system, but it isn't as straightforward as the 80 series is.
For example, the outside mirror controls have their own ECU, which has to communicate with the ECUs in the tilt and telescopic wheel systems, in order to work. It's far more complex than is necessary, but Toyota was trying to out-Cadillac its competition, and this is what we got.
For example, the outside mirror controls have their own ECU, which has to communicate with the ECUs in the tilt and telescopic wheel systems, in order to work. It's far more complex than is necessary, but Toyota was trying to out-Cadillac its competition, and this is what we got.
Malleus
Far west of Siegen
If the problem is with the communication bus, this method will indicate that and you'll be on your way to resolving the problem.
- Thread starter
- #11
I’ll try this and get back. Thanks for the help! If anyone else has any other ideas I’m all ears. I do want to try and fix myself.
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- #12
Having a hard time locating these
Malleus
Far west of Siegen
Sorry (for the late reply - I was at the beach), I thought they were in there. Well, they are now. I've posted the entire FSM, EWD, body repair manual and new car features brochure. Happy reading.
Post back when you have had your fill of the communication bus section and we'll try to get your problem solved.
- Thread starter
- #14
Well, I found that the cigar fuse in the driver footwell box was out, so I replaced that one and low and behold, the mirrors, radio and HVAC now work! However, the HVAC and the dash lights (backlight behind the gauge needles...for some reason those are lit while the back is black) are not working...nor the lights I normally see at the bottom of the dash screen for items like Check engine, SRS, etc. Normally they flash when you turn on the car...now nothing. But here is something crazy that happened this AM....I drove it for about 15 minutes to the store and all of a sudden then came on.....then 5 minutes later they went off. Any thoughts? I checked all fuses in the boxes a second time now....can you check relays or is that impossible?
Malleus
Far west of Siegen
Sounds like you got lucky and you may have a loose connection somewhere. Check anywhere someone has been unplugging stuff...
Yes you can test automotive relays. They're magnetically operated switches.
Yes you can test automotive relays. They're magnetically operated switches.
Malleus
Far west of Siegen
The FSM has specific inspection procedure instructions for relays. This is an example, for the EFI main:
When you're "applying battery positive voltage", you can use light gauge jumper wires from the battery directly. 12VDC won't hurt you. If you do this, remove the negative lead from the battery FIRST. This way, you remove the risk of damaging the electrical system. In a perfect world, you'd use a dedicated 12V power supply, but most people don't have one of those lying around. I still don't, and I've needed one for about 4 decades.
Shameless plug: if anyone has one lying around, feel free to contact me
When you're "applying battery positive voltage", you can use light gauge jumper wires from the battery directly. 12VDC won't hurt you. If you do this, remove the negative lead from the battery FIRST. This way, you remove the risk of damaging the electrical system. In a perfect world, you'd use a dedicated 12V power supply, but most people don't have one of those lying around. I still don't, and I've needed one for about 4 decades.
Shameless plug: if anyone has one lying around, feel free to contact me
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