thermostat sensors?

full_thr0ttle

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Apr 25, 2005
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i was wondering if someone could tell me what each of the sensors are on the thermostat housing, and what colour the wiring is that goes to them.. i had to fix a hacked harness and i think i may have screwed up..

its a 1990 GTE harness, thanks a lot
 

Jaguar_5

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Feb 7, 2006
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This comes up way too often, and really should be stickied or added to a tech-tips page with commonly referred to reference images like this one, and maybe the one that identifies stuff all over the engine bay, and there's one for underneath the car as well
 

GrimJack

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Dec 31, 1969
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Jaguar_5;1074255 said:
This comes up way too often, and really should be stickied or added to a tech-tips page with commonly referred to reference images like this one, and maybe the one that identifies stuff all over the engine bay, and there's one for underneath the car as well
Make the thread, put everything together in one place and send me a PM, I'm more than willing to move it to the area and sticky it.
 

Jaguar_5

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I'll pm you in a few days when I have some spare time, it might be tricky to find some of those pictures so if anyone knows the ones I'm talking about feel free to chime in ;)
 

Who

Supramania Contributor
Jaguar_5;1074483 said:
I'll pm you in a few days when I have some spare time, it might be tricky to find some of those pictures so if anyone knows the ones I'm talking about feel free to chime in ;)

Found these on the forum and saved them. Not my photos.

Kudos to bishop92t
 

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Jaguar_5

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Feb 7, 2006
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Wow, thank you both very much! That would've probably taken ages to find had I not remember it was on Bishop's site

I'll compile it in the next few days when I'm abit less busy!
 

Jaguar_5

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Feb 7, 2006
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Those two images disagree with the AC fan switch and the Aux fan switch... so which is which?

I'm having a hard time finding it in the tsrm
 

Kckazdude

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Mar 16, 2007
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The earleir (87 & 88?) harnesses dont have the connector for the A/C fan switch. I was confused but found as many pics as I could of earlier models to confirm my suspicion of this. All of the 3 port t-stat housings are on 89+ cars. As are all of these pics referenced.
 

Kckazdude

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Mar 16, 2007
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Yup you confusled my mind.
I have a turbo harness (2 knock sensors, shorter TPS lead, 4 lead AFM) and no blue A/C fan switch connector. After reading all the way through gtsfirefighter's build thread I see he also doesnt have the connector. Found a few others after a day of searching through build threads. Checked at the ECM connector and it is blank on that end.
 

jetjock

creepy-ass cracka
Jul 11, 2005
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Redacted per Title 18 USC Section 798
The GE in that thread shows two ports while the GTE shows three. Since the TEWD and TSRM tend to agree with that it appears to be a N/A versus turbo issue concerning the number of condenser fans, specifically the pusher fan. Also if auto or 5 speed. Mine 87T manual looks exactly like the pic Grim Jack posted.

That said there are several mistakes in the TSRM concerning condenser fan operation. There's also wiring variations in condensor fan operation between early and later model years. For example the earlier years only have two fans and don't have headlight integration for the pusher. Hell, my 87 TEWD doesn't even show some of the wiring and switches associated with the AC system. I had to figure it all out. The books are somewhat of a mess when it comes to this and a few other things. Anyone whose had to deal with the factory alarm schematic in the 87 TEWD knows what I mean.
 

Kckazdude

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Mar 16, 2007
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I have noticed that the switch seems to also concern the pusher fan that I have seen on some cars and not others. At first I thought it was a turbo/NA difference. I have seen turbo cars that didnt have this fan though. I have the pusher fan and the front harness from a 87 turbo car that I was planning on installing. Now I am thinking on ordering a new engine harness from Toyota. Wasnt really planning on it but this third port issue is worrying me now.

Here is the post I was refering to about Kens engine.
 

jetjock

creepy-ass cracka
Jul 11, 2005
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Redacted per Title 18 USC Section 798
Oops, the switches are labeled correct. Guess my eyes aren't what they used to be. Post edited.

I see what you mean about Ken's thread. I was looking at the first post/photos. Appears he swapped housings later on. It's confusing.

Something I've never bothered to figure out is the story on the upper switch. It's supposed to disable AC operation when coolant temp reaches 234 F and is connected only to the AC amp but is not labled as switch number 2 in the TEWD. It *is* labled as such in the TSRM though. Plus that switch shouldn't control fan operation yet mine does, along with the other switch on the blue connector. Worse, the switch that controls fan operation is labeled as number 2 in the TEWD when it should be labeled as number 3, which is not shown anywhere on the schematic.

I dunno. Appears it took Toyota time to get all that sorted out and the books don't match up. Whatever the case I use the 234 F switch as a high temp alarm so I don't have to watch the gage. I wired a Mallory Sonalert to that line under the dash to let me know if coolant temp ever gets that high. Been there for years but fortunately has never come on.