KahnBB6

iTrader: (5)

I'm looking at buying a new or used set of factory seat heater switches that are found in the SC shifter bezel (A/T or M/T). I'm looking to repurpose them for aftermarket functions and sand, re-label and re-seal their paint and finish.

My car doesn't have them and I've never never seen them up close on another SC. Couple of questions:

They definitely are not backlit, correct? Just a simple orange LED that is on or off?

I can see that they are "rocker" type switches. Are these generally easy to bump on and off by accident? Especially in an M/T model where they are located on the bottom of the shifter bezel? Or are these switches generally hard to hit by accident in an M/T car?

Oh, and lastly, can anyone confirm that the same switch assembly fits both A/T and M/T bezels?

Thanks!

*Not my photo. Just an example.

Biddles

iTrader: (2)

They are not backlit, just an orange light that indicates whether it's on or off.

They are rocker switches, but I wouldn't consider them easy to hit on/off. I don't see you bumping them on a M/T car unless you have a broken wrist.

Toyota likes to use the same parts whenever possible, I doubt the switches are different between A/T and M/T cars however I can't say for sure.

KahnBB6

iTrader: (5)

Thank you Biddles! That's good enough for me. My biggest concern was that they might be light to the touch to switch on/off. My guess was also that they are plug and play between the all of the A/T and M/T bezels even if the USA part number states "SC400 w/o TRAC".

There is a similar thread on SF to repurpose factory dash switches (backlit in the case of MKIV's) and liked the idea. I won't ever use heated seats in this car and they're the only optional factory switches we have available.

One will be for sequential twin TTC/ETTC mode and the other I'm not sure about yet.

pogoism9

iTrader: (1)

The trac cars share the same connector with the seat heater switches. If you buy a used switch setup with trac you can depin and remove the trac button

KahnBB6

iTrader: (5)

^^ Thanks for that info! This suggests that the same connector was used for the TRAC/Auto cars with heated seats and for 5-speed/Non-Trac cars with heated seats. Unless the 5-speed center console harnesses are different.

pogoism9

iTrader: (1)

Since the 5 speed cars never came with TRAC, the 5 speed cars use a totally different connector. See attached. Its very easy to work around as long as the switches fit into the bezel (I suspect they may).

The 5 speed connector is S8 in the attached document.

KahnBB6

iTrader: (5)

Thank you, pogoism9. I've looked at the S8 connector in that diagram and it does look very similar to the flat style connector in the picture I posted above.

I'm probably overthinking this since I'm really not trying to wire my car for heated seats but rather reuse the switches for something else. I may as well use generic connectors for this.

If the dual switch assembly itself is identical in shape for all models with only the connector being different for A/T and M/T then that would make it easier.

However, when I look it up through Toyota I see three versions:

SWITCH SC300, SC400, Manual Trans
SWITCH SC300, SC400, Auto Trans w/o Traction Control
SWITCH SC300, SC400, Auto Trans w/Traction Control

So maybe they are shaped differently for the A/T and M/T models. Also kind of odd that the M/T version is listed for the SC300 and SC400.

Edit:

I found some pictures of the A/T w/TRAC heat switches and one of the underside of the M/T shift bezel with heat switches and compared both to my own shift bezel. It looks like the heat switch assembly is indeed the same for all... except for the wiring as you pointed out, pogoism9.

KahnBB6

iTrader: (5)

I just picked up a used A/T version of the switches off ebay to get started. They'll be rewired anyway.

KahnBB6

iTrader: (5)

A/T seat heater switches came in.

I think the two functions will be:

"TTC / OFF" (electronic true twin conversion aka E-TTC)

"IC SPRAY / OFF" (external water spray to the intercooler to reduce heat soak)

Kris9884

iTrader: (7)

That's awesome, although if it were me, I would always have TTC on lol. The water spray switch is a great idea, way better than some mission control launch style button.

KahnBB6

iTrader: (5)

lol, I hear you! Sequential isn't everyone's cup of tea. But I'll need it anyway and I'm looking forward to the response at stock/semi-BPU. Also, apparently using E-TTC too much causes increased long term wear on the pressure tank (not the case with "permanent" TTC). There are better ways to get more power from the stock twins. My idea is actually to use it in poor weather conditions or any time when I'd prefer not to have as much immediate low end power. Or at least very linear power when traction is very low.

I'm not expecting any power advantage from an IC spray but since I'm going to use an MKIV side mount IC I think it will help on very hot days

KahnBB6

iTrader: (5)

Very brief update mostly to keep track of notes for this:

A thread with some details about how the wiring for these switches work. Will add more notes as I come across them.

https://www.clublexus.com/forums/sc-...ac-cotrol.html

KahnBB6

iTrader: (5)

Some investigative pictures and test notes:

I removed the TRAC button and wiring from this harness, leaving only the seat heater switch pins. This is from my A/T w/ TRAC version of this switch assembly. A 5-speed harness plug will look different.

The white rear plastic cover has also been removed.

Note two round switches that can be rotated with a small screwdriver.

What I wanted to do was make sure I could identify which circuit went to what wires. I used a multimeter with a 1.5V AA battery applied in line to test each set of wire connections (black and white for one switch... and blue and white with black stripe for the other).

Unfortunately what I found is that both circuits seem to be tied together and are not completely isolated. I reviewed the PDF diagram Ali SC3 posted in the other thread listed in my previous post and the schematic seems to confirm this.

If what I want is to re-label and repurpose these switches to operate two totally different +12V electrical circuits I may have to break into the assembly further and completely redo the wiring on the rear.

Although the copper tracing might be fairly simple to modify and re-solder.

t2d2

iTrader: (8)

Those are just the bulbs, aren't they?

I tried figuring out the seat heater switches awhile back for potentially hooking up to aftermarket heaters, and came to the same conclusion as you that the two are tied together.

KahnBB6

iTrader: (5)

^^ Yes. This afternoon I further pulled apart the assembly and discovered that they are just bulbs.

It is surprising how simple the rocker switches actually are. The complexity of the circuit comes entirely from the copper layout on the underside of the removable black panel (which is clicked into the main assembly underneath the white outer protective under cover).

I think what I will do is cut through the copper at specific points an remove and re-solder a couple of the wires to make each rocker switch circuit operate independently. It looks possible to retain the bulb functions for each while doing this.