I've searched for hours on this topic and haven't found this exact same issue, so help would be greatly appreciated.

Some background on my car:

'92 SC300 w/1JZ-GTE swap and R154 done by previous owner. Car has always been manual transmission.

Previous owner also installed the wrong OEM radio and radio/climate control harness at some point, which I found out when I went to install my new double-din head unit. The harness that was put in was for a car with dual Pioneer amps, but my car only has one. Thus, the radio itself not working either, although the climate control did work (the climate control was out of a Soarer).

So, I put in the correct factory radio/climate control harness before installing my aftermarket Pioneer head unit, and the radio works perfectly. However, my climate stopped working. The cigarette lighter fuse DID blow, but after replacing it the unit still wouldn't light up at all. All fuses in kick panel and under hood are good now, but here's the really weird part. Pressing the Auto Temp button does nothing, but if I press the HAZARD button the climate control starts flashing, and the blower fan turns off and on with the flasher! The hazard lights themselves, however, do not light up.

Any idea what gives? I bought a spare climate control unit (out of a '92 - same year as my car) and that didn't change anything. It seems like something else besides the radio wiring was different on the old harness, and maybe the "ignition on" wires on the Auto Temp and hazard light plugs should be swapped?

 

Almost sounds like a ground issue.

 

Ahh, interesting. I had considered that, but I don't know enough about electrical to be certain that it might cause those issues. I wish I had a wiring schematic so I knew which wires might need to be grounded.

Thanks for your input!

 

Also, out of curiosity, does the cigarette lighter complete a circuit, or does it simply "piggyback" off of the climate control wiring?

 

I believe I may have figured this out. It appears that the radio/climate control **** is also out of a '95-96 SC w/CD changer, so the wiring is different. I compared the old harness I took out with the one I installed, and the wire colors are somewhat different. I bet the ***** require a common ground, which the car no longer has due to changing to a non-CD changer harness. I guess I'll just hope that the car I got the harness out of is still at the local Pick-N-Pull.

 

Thats what I was also thinking, a bad ground or the wrong interchangeable parts installed.

 

Both. Can't power the A/C with the fuse popped. lol, by any chance, did you switch the buttons around or something?

 

I wish it were that easy. Haha

The wires for the climate control and radio just go to the green and orange plugs?

 

Not sure about the **** being different but the harness is in deed different. Not by much but it is different and causes the hazard button to make the heater blower "flash" instead and when you try to turn on the heater or ac or vent it wont come on unless the car is not started.I had my stereo stolen out of my 1992 sc300 and they ripped up y climate control radio harness and I bought one out of a 99 from aliga on here and the harness plugged in the same but I had the exact same issues you are experiencing.The 1992 harness has an extra little connector in the harness that has a box wrapped in foam and that has something to do with the hazard lights...something that the newer harness don't have in them. I bought another radio/climate harness out of a 1992 or 1994 sc400 from uzinator and it was exactly the same as my damaged one minus being damged...lol fixed the issue 100% though...climate control and radio worked just perfect again.

You just need a harness out of an earlier sc that has the one extra connector that is part of the radio and climate harness that connects to the little foam wrapped box that is tucked in back by the raidio... My harness I got from uzinator had the foam wrapped box included too...lol I could find a pic if really need be but ya I think you should be good.


Hope that helps! I will try and find my old classifieds thread where I figured this out myself...

 

Found my old classified wanted ads not sure if they are much help but they do confirm my previous post.

https://www.clublexus.com/forums/sc4...f-it-also.html

https://www.clublexus.com/forums/sc4...992-sc300.html

 

Yes! I have the harness with that foam covered relay or whatever, but I believe that my volume/climate ***** and flasher are both out of a 95 or 96, probably the same car the old harness was from. I bought one from the wrecking yard yesterday but I think it's faulty since it won't even flash now. The '92 donor car had a cd changer/ dual amps, so maybe that's still an issue. I figured that for $10 it was worth trying.

Does your car happen to have the factory CD changer? If not, do you happen to know the part number of the climate control **** you have? Thanks!

 

I will check on the part number of the **** in my car today when I go out there to install the intercooler. I have no factory cd changer anymore. The previous owner removed it. There was a double din cd player installed when I got it. The previous owner even wired the volume **** to work my power antenna...Volume up the antenna goes up volume down the antenna goes down... I know that you have to tie into the factory amps wiring somehow and branch your speaker wires in the trunk that went from the factory amps to the door speakers so you dont have to run speaker wires fro the deck to the cars speakers...Or if you are running an aftermarket amp with your stereo then all you need is a power accessory power and ground to get the deck up and then run wires from your aftermarket amp to your speakers/sub or fro your deck directly to your door speakers etc. Are you saying you have no power yto your stereo copletely or that the volume **** isnt controlling your aftermarket deck? Cause the volume switch wont do that...its only for the factory stereo.

 

Sorry, lack of sleep due to two toddlers is affecting the way I write things these days. haha

My main issue is that the climate control is no longer working after putting a '92-94 harness back in the car. The previous owner had put in a '95-96 harness, radio, and climate/volume *****. I'm only worried about getting the climate control working again, not the volume ****.

My car never had a factory CD changer, so it didn't use a "common ground" setup like the car's with CD changers, which also had an external amp for the door/shelf speakers. Instead, my main amp would have been inside the head unit like most aftermarket head units, although there is still a separate amp for the sub.

When I installed my new head unit, I simply had to use a standard Toyota adapter to get most of it working, and I spliced into the sub amp with an RCA cable. The radio itself works flawlessly, and even the antenna's different stages all work, it's just that now the climate control won't turn on.

I'm now wondering if I might have left something disconnected somewhere, but the only plug left is a square-ish gray plug behind the radio, but I don't think that was hooked up to anything before.

 

Well, the issue is persisting...

I bought another temp **** assembly, and even a flasher unit, from another '92 SC300 w/o CD changer, and once again the climate control flashes when I push the hazard button.

Is it possible (or better yet, likely) that the radio/climate control harness I bought is faulty somehow? The radio I installed works great, but maybe something in the rest of the harness is messed up?

I'm sort of wishing I had never installed the stereo, because at least the climate control worked prior to that!

 

Did you ever figure out how to make everything work?





I have a 1995 Lexus SC400 I got it from a teenager and I am trying to restore it to its factory look. The car had an aftermarket radio and I removed it. I discovered cut it up wiring behind it so I went to the junkyard because I wanted the 12 CD disc changer. I got the entire wire harness that connects to the harnesses that come at the bottom underneath the radio and swapped them out and discarded the old harness. Prior to swapping them out, the climate control, AC and hazard lights worked and now the climate control has no power and the hazard lights don't work but the signals work and the cigarette lighter works. When I cut on the lights the climate control buttons light up just the buttons though not the screen. now I don't know what to do the CD changer and radio work great but now I don't have AC or hazard lights someone please help is there any way anyone knows where the ground wires are or what I should do to correct this problem.