KahnBB6

iTrader: (5)

Question for those who have looked into harness wiring, etc.

For a STOCK 1992-1997 Non-VVT-i SC300, how does the dash temperature gauge receive its signal?

Does it interface directly with the ECU in such a way that the ECU might affect the final output signal to the gauge?

Or does it just go directly from the coolant temp sender on the block (or head)... directly to the gauge... with a secondary wire or two splitting off to give the ECU its electrical signal?

Thanks, all!

KahnBB6

iTrader: (5)

I think I got my answer on post #845 of the ECU capacitor thread (two separate sensors).

https://www.clublexus.com/forums/ls-...acitor-57.html

Will lock this thread up shortly unless someone thinks I've got it wrong.

t2d2

iTrader: (8)

Keep in mind, that's a LS400 thread. I was going to say that's the way the SC400 is after reading this thread title, but who knows if the SC300 is set up the same way...

KahnBB6

iTrader: (5)

Good point. At the moment, I don't have a solid answer.

Vrank

iTrader: (4)

There is 100% zero interference of ecu with temp at cluster. When doing your swap, this should have been apparent. You will have TWO coolant temp sensors on ALL non-drive by wire cars. a SINGLE wire which is for the cluster, which also has a ground reference that runs back into the engine harness to the intake, then the TWO wire sensor that is comprised of circuits E2 and THW, which go to the ecu ONLY, to determine fueling compensation based on temperature.

The one on your dash has nothing to do with ecu, and in an sc400, IF wired up properly, works 100% normal and proper with any appropriate single wire jz temp sensor

KahnBB6

iTrader: (5)

Vrank, thank you! This is exactly the info I was looking for.

Not related to my swap in this case. I was trying to verify whether or not I was having a coolant sensor or ECU issue affecting my temp gauge. So the 1-wire temp sensor is all that *could* have affected it and NOT EVER the ECU.

It turned out to be low coolant issue due to a leaking heater core hose in my case, however I am glad to know this once my swap gets underway.

Thanks again!

Vrank

iTrader: (4)

No prob, I was under the impression you were done? but yeah, make sure you bleed it well after having a leak. Also, if you dont have one of these, get one. Jack front slightly up, and turn heater full blast. Makes life simple, look on amazon or something as I think link will disappear

lisle 24610 spill free funnel

t2d2

iTrader: (8)

Interesting product. I might have to pick up one of those. It looks like #24680 is a new and improved version, and is actually cheaper.

KahnBB6

iTrader: (5)

Nowhere near started, unfortunately. Just the parts for it and the research at the moment. But I'm very close to beginning getting it underway, finally.

What you describe is what I did with the exception of jacking up the front (which I'm aware is recommended for Supras and SC's when burping radiators). I did end up getting a spill-free funnel from Pepboys based on a similar one I saw reviewed on youtube. I was expecting $26 or so but it ended up being $55! And it worked but did not seal correctly with my Koyo radiator no matter which attachment I used. Applying pressure with one hand solved it but it wasn't ideal, despite the quality of the kit.