I am re-visiting this issue again from my previous postings. I have an issue now that has just started with interior illumination back lighting on the HVAC. The previous ongoing sage issue still continues with the center console gear shifter illumination light not working, this also seems to affect the illumination light also on the light in ashtray cigarette lighter ring, which work previously. I have heard of individuals unplugging the the HVAC plugs and having success, but not in my case. I have used electronics cleaner on the plugs. I have taken out each of the fuses out of each J/B boxes. Used steal wool to clean the male end of each fuses contacts to a shine some were they looked dirty from overtime dulling. My next step is how do you remove the driver side J/B ECU to investigate or do you replace the whole drivers side J/B ECU with the fuses? I am not having any luck at this time, any help would be appreciated.

 

OK. You are going wayyy too deep here.

Just tell me what does not work and give me some time to look into it. The center console has one small interior bulb with a green plastic cover. did you check it?

Paul

 

Yes, and replaced it was burnt out. It will work just on its on time This issue is has been on going since I have owed the car which I love. Just annoying at night time. It was working pretty good. Then in the last year no positive results. Also the HVAC back lighting lights are not lit now and the ashtray/cigarette light light not lit also. Thank you

 

OK. Shifter indicator lamp.
Cigarette lighter and HVAC backlighting. Is that all you are aware of? I am looking up the schematics now to see what might be going on.

Paul

 

Thank you very much for your help.

 

Do you have this schematic?

See if you can manipulate the "Rheostat" to turn intensity up and down on everything that works. All of your problems, shift lever, ac control illumination, audio door is also tied in. All of these signals do come from the "White-Green" wire on the driver side ECU, D5, Pin 12. Check your grounds. But it's easy to check.

It should be +12vdc when the headlights are on.
Connector D5 is located here. You need to locate the white-green wire.

You can make the same measurements at the bulb. Anything else we can help with at the moment?😁

Paul

 

I would be remiss in saying that "If" it is the ECU, you may reset the problem by pulling the battery terminals for a few minutes. Less time if you can tie the + and - cables together after you remove them from the battery.
And I have to say from recent personal experience troubleshooting my own system AND installing both downstream sensors. That location SUCKS DONKEY *****!👍

Paul

 

I am trying to learning to read the drawings. I do not have any of the Lexus books at all on how to read the wiring diagram legend for each wire gets confusing. It is all a learning process for me the way the numbering and letters combinations. Is it hard to access the driver side ECU to get to the plugs and ground wire. I did clean all of the fuses and the fuse plugs. Again thank you for reaching out to my little cars problem. I would think she would be happy to have all her lights working and on when they need to be. Again thanks.

 

Absolutely no problem Sir. If you take the information I provided to a decent shop, they will be able to diagnose the problem. Good luck.😁

Paul

 

Anyone think it might be the headlight switch? Usually there are two positions. First click is for the accessory lights and then a second click for the headlights. Think the switch could be bad? maybe he Could be running on DRL's only?

 

No, the only lights he doesn’t have is the shift control and the climate control. I was thinking the dimmer switch but that would dim the instrument cluster also. It probably is loose wires or connection .

 

I was hoping for a simple find. I did think about the light switch also as a possibility as you have said also. It is a very humbling experience to say. I have also used a harbor freight electrical kit. This is were you hook a 9 volt battery or low voltage supply, to the shifter console illumination plug with a clip. This allows you to trace with a sound or noise probe to see if anything could be broken. But to no avail. I will keep digging in. Thank you guys for the help. One thing is it possible to pull the carpet away from the were the emergency brake is to get to the driver side ECU/JB to investigate. I have started to try and it is hard to get it to pull down in behind the emergency brake. Afraid I am going to tear the carpet or mess something up. Thanks again.

 

Revisiting this issue and tested the white/green wire while UNPLUGGED on the shifter illumination connector with a multimeter. Multimeter read 0V. Occasionally, I would get a tiny spike in voltage up to about .3V. To make sure the multimeter was operating correctly I tested the battery’s voltage, and it was reading close to where it should be. I am assuming it is not getting any power to the white/green wire for the shifter illumination connector. The white/green power wire from shift illumination light runs through one junction block before reaching the driver’s side ECU. I am assuming the problem is a power issue somewhere between the bulb connector and the driver’s side ECU. On the ground side, green wire going into glove box light connector originating from the shift illumination I am getting .2V. Red/white wire coming from glove box light connector has 0V. Red/white wire going to glove box light switch also has 0V. Black/white wire coming from glove box light switch to the actual ground is reading -.02V. This is all the testing I’ve done tonight. I may be checking the wrong places, but I feel I am beginning to get on track with tracking this issue down.

 

I think you might be in luck. It looks like there is a FUSE #5 that operates the lights in the HVAC and glove box, but not the rest of the the interior lights. Take a look at this fuse diagram

https://fuse-box.info/lexus/lexus-sc...001-2010-fuses

The quirky part is why it is intermittent? I might guess that the fuse clips aren't tight? Or possibly the connection to the fuse box isn't tight? Most likely it is a loose wire somewhere that is shorting the entire circuit run by fuse #5

 

Ok thank you very much for the information.