Hi guys
I bought my GS a few months ago with 98,000 miles for $1,700 at a dealer auction. It's been a super great car but there's one new issue that's bugging me.

A couple of days ago I put a new battery in my car. That night I went out to do some things and the lights on the climate control were not lighting up, additionally the lights on the shift lever were not lighting up either (but they were really intermittent before). If you turn the headlights off, the screen on the climate lights up, but of course no buttons.
I searched around online a bit trying to find a solution, tried unhooking the battery for 30 minutes, touching the cables together when unhooked and checking some fuses all to no avail.
So now I'm trying to figure out whats causing it not to work. I don't know if there's a relay for it, or if anybody knows if there is a way to just hotwire the lights to always be on when the car is on, ignoring the status of the headlights.
This one has me scratching my head a bit.

 

to the left of the steering wheel there is a dimmer switch. I'm not near the car right now but I think it's near the side mirror adjustment panel and security light

 

I did think of that, played with it for a while and it seems to dim the gauge cluster, but has no effect on the climate control lights.

Seems like it has to be a fuse, relay, or the unit just failed. I've spent some time searching on it online, and while none of the answers were GS specific, (most were for an RX) I tried unhooking the battery and whatnot to reset the system with no success. It would seem strange that the unit would fail at the same time as changing the battery, so I'm guessing more like fuse or relay, I just can't seem to find what fuse it would be connected to or if there is a relay for that lighting someplace that I should check.

 

Do you have an aftermarket stereo?

 

Yes I do.
Also, it had been working great for over a month since the stereo was installed.

 

Tried looking at wiring diagrams? on there you can trace every fuse, relay, connection etc.

 

I figured that's my next step.
I just need to find a diagram, then start studying it.

Was just hoping somebody would be able to point me in the right direction before I try to understand one of the diagrams. I always seem to get confused by them.

 

I have this issue but haven't had the time to diagnose.

My car is a GS300 with a Pioneer deck. I installed a custom tablet in place of the headunit and made my own harness.

I believe there are two ground wires in the stereo wiring harness - one is constant ground, and the other is grounded when lights are on. I would start there.

Here is a picture of my initial harness (note, this is the female side of the connector that plugs into the stock harness). As you can see, I have a green/black wire, and solid green wire. Initially, I treated both of them as constant grounds.

The black with green was used to power my head unit, which would sometimes turn off depending on which position my headlight switch was in. As soon as I switched everything to the solid green wire, the climate control backlight started behaving like yours.

Note, I pinned this harness myself, so your colours will differ. This is just to show you the position of the wires. I believe the actual ground wires were white/back.

 

Interesting. I'll look into it.

As of right now, the heated seat switch (I don't have heated seats) appears to have a working illumination circuit. I played around with a multimeter and found which wire appears to control the illumination.
Now going to move to the climate and see if it's working there, indicating a bad unit, or if it isn't. If it's not working, I intend to make it work by rewiring if need be.

 

This has got me pretty stumped.
I have been looking all over the wiring diagrams I've been able to find and it has to come down to a junction, relay, or fuse.

I work at a car lot and we just got another GS in so I went and took the dash apart on that to check a few things.
-I swapped out the controller and have the same result with one that is known to be working well, also when I put mine in the other car, it functions as it should. So the issue is not the unit itself.

I probed around with a multimeter on the good system and did find a single wire that appears to trigger when the lights are turned on or off. Initially I assumed it was what turned on the lights within the unit while the lights are on, but now after more thought I'm thinking that may be whats flipping the relay to turn them off, essentially half of the system to turn on the full lighting.
So now I think I just need to dig further back and see if I can find the other half, the one that turns on the backlight and the lights on the buttons.

In addition to the climate control lights (really all I care about), the light for the hazard switch, shifter, and VSC/Snow mode switches do not light up.



Ultimately I don't think it's related to my head unit. I ran a ground to a bolt in the dash, and spent 2 months with it working perfect before this issue.

I suppose I'll try resetting the system again, though it hasn't seemed to make a difference in the past.

If anybody is a wiring genius I'd greatly appreciate any input! Even just a direction of where to start tracing back or how to just make them work, I know enough about wiring to put a relay in so that the lights all come on when they are supposed to, if I just knew what wires needed power...

 

I have the diagram book but I left it home. will look at it tommorow.

 

Any chance you were able to find anything?
This still has me stumped.

 

are you sure the bulbs in there are still good? a lot of mine went out and i had to replace them...

 

Positive bulbs are good. I plugged my unit into a different car and it lit up just as it was supposed to in the other car. When I plugged the unit from that car into mine it did the same thing mine has been doing.
In short, it has to be the unit not getting signal to turn on all the lights

 

try panel fuse in driver side.