Lower Temperature Coolant Temperature Switch For ST185

On my 94 Toyota Supra Turbo, I installed an OEM Toyota coolant temperature switch on the bottom of the radiator that is rated to come on 8 degrees Celcius sooner than the original one.

The original one switches the fan on at 98 C then turns it off at 93 C while the replacement switches the fan on at 90 C and then turns it off once the coolant temperature cools to 85 C. The replacement # is 89428-33010

According to the diagram on amayama.com https://www.amayama.com/ru/catalogs/toy ... mputer-337
, this same switch will fit the All-Trac.

I think I am going to get one for my Celica.
 

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Roreri

Active member
That’s a nifty idea. I’m always thinking about how hot the 3SGTE trends. I wonder if this would help somewhat or whether it would just mean the fan is always on.
 
On my supraforums.com post I wrote:

"I installed the radiator temperature switch 89428-33010. It looks identical in dimensions compared to the original. It also comes with the rubber O-ring. The radiator fan now cycles on and off as it should. However, as expected, it comes on sooner and seems to stay on longer. If you don't mind this trade off, then this is a nice option if you want the fan to come on at a lower temperature."
 
At least for the 1990 USDM All-Trac, the part number for the engine coolant temperature switch is 89428-15030 (which is not on the table supra-raleigh provided).

According to the service manual, the switch turns the fans on at 93 C (199 F) and turns the fans off at 83 C (181 F). That would make this original All-Trac engine coolant temperature switch much closer to the replacement switch supra-raleigh found than the original engine coolant temperature switch specs for his 1994 Supra.
 
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