Does your 4Runner have a transmission thermostat?

[Burgi]

My transmission on my sr5 4x4 is absolute dog poop. Constantly slamming gears, jerks, bucks etc. I went to check the transmission fluid which requires you to pin the thermostat. I don’t have a thermostat. I went to the dealership and looked under a bunch of Tacomas and 4Runners and they all have transmission thermostats. The dealer didn’t have any sr5 models but I looked at TRD OR and a limited and they have thermostats. Did they forget to install one at the factory? Can anyone with a 4x4 sr5 take a look at theirs? Thank you


Mine

TRD OR

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[Dr_Al]

I don't know about the 4Runner but my Tundra has the heated radiator line that goes from the engine to the cab heater core and then to the transmission. It's job is to heat up the transmission. Once it's at temp then keeps the temp at a specific temp. My Tundra also has an external radiator (part of the towing package) that adds extra cooling. That has a thermostat that has to be bypassed so trans oil flows to it when checking the oil level. The Tundras that don't have the extra cooler don't have the thermostat. By looking at those pictures I'm guessing you don't have a thermostat.

 

[Burgi]

I don't know about the 4Runner but my Tundra has the heated radiator line that goes from the engine to the cab heater core and then to the transmission. It's job is to heat up the transmission. Once it's at temp then keeps the temp at a specific temp. My Tundra also has an external radiator (part of the towing package) that adds extra cooling. That has a thermostat that has to be bypassed so trans oil flows to it when checking the oil level. The Tundras that don't have the extra cooler don't have the thermostat. By looking at those pictures I'm guessing you don't have a thermostat.

thanks for the reply. I looked all through the cooling system and can’t find one anywhere. I do not have an extra cooler either. All I have are the radiator and an intercooler for the turbo.

 

[mmjsport]

I'm curious if we could add a theromstat and how much of a difference it would make.

 

[Vincenzo]

If you plan on towing, your vehicle is the perfect candidate for an external cooler.

 

[bkw777]

I don't know where the physical sensor is, but the dash has a display option that shows transmission fluid temp and oil temp. SR5 4WD

 

[IconicFJ]

It would be amazing if I could get a few users to reply to this with their 6th gen 4runner model year and packages. And whether or not their truck has a transmission thermostat or not. This PDF outlines the 3 equipment types these 4runners can come with. My question is which models come with what parts?

My 2026 TRD ORP comes with the bottom option, "model with oil cooler assembly" and it doesn't have a thermostat.

 

[127.0.0.1]

what do you mean pin the thermostat ?

if you want to check fluid level there is a start/shift procedure and the system will let you know when the fluid is warm enough but NOT 113degF or higher. if higher than 113F you cannot accurately set the level need to let it cool down and start over

toyota suggests you start at 68degF (cold basically) then if you do the below the D indicator will let you know when you can check the level with the standpipe in the drain plug hole

ADJUST AUTOMATIC TRANSMISSION FLUID TEMPERATURE (when Not Using the GTS)

NOTICE:

• Make sure to switch to automatic transmission fluid temperature detection mode within 60 seconds after starting the engine.
• At the automatic transmission fluid temperature detection mode, the D shift indicator illuminates for 5 seconds before it flashes when moving the shift lever to P or N if it is an appropriate temperature or higher.D Shift Indicator at Automatic Transmission Fluid Temperature Detection Mode
  

  	Below Automatic Transmission Fluid Level Adjustment Temperature	Automatic Transmission Fluid Level Adjustment Temperature	Above Automatic Transmission Fluid Level Adjustment Temperature
  Automatic Transmission Fluid Temperature (GTS Display Temperature)	35°C or less (95°F or less)	35 to 45°C (95 to 113°F)	45°C or more (113°F or more)
  D Shift Indicator	OFF	ON	Blinks

again, a drain and fill is done cold. you only need it barely warmed up under certain
circumstances. if you drain more than 50% the fluid you need a TON more done

---
How to get into fluid temperature detection mode ? a shifter dance


(a) Turn the ignition switch off. [#2]

(b) Depress and hold the brake pedal.

(c) Start the engine.

NOTICE:

To reduce load, make sure that all electrical systems, such as the air conditioning and audio system are off.

(d) Slowly move the shift lever from P to S, from S to 1st, and then back to P.

HINT:

• Keep the shift position in each position for approximately 3 seconds.
• Slowly move the shift lever to circulate the automatic transmission fluid through each part of the automatic transmission assembly.
  
  
  

• (e) From the shift position in D, move the shift lever between N and D within 1.5 seconds for 12 seconds or more continuously to switch to automatic transmission fluid temperature detection mode. NOTICE: Do not pause for more than 1.5 seconds. HINT: The automatic transmission fluid temperature detection mode will be activated by moving the shift lever between N and D within 1.5 seconds for 12 seconds or more continuously.

  *a Shift Position *b Indication of Shift Position *c Automatic Transmission Fluid Temperature Detection Mode *d 12 sec. or more *e 2 sec. *f Less than 1.5 sec.

  (f) Check that the D shift indicator comes on for 2 seconds and then turns off.

 

[Rotor-RPM]

It may be my lack of understanding things in general but wouldn’t having a thermostat-less transmission mean that your always running it cooler cause it’s always flowing?
I could be completely out to lunch here though sorry.

Im 23000km and I haven’t noticed any issues with the shifting on my SR5. Everything from -30c to +30c has been great.

 

[Bindul]

My transmission on my sr5 4x4 is absolute dog poop. Constantly slamming gears, jerks, bucks etc. I went to check the transmission fluid which requires you to pin the thermostat. I don’t have a thermostat. I went to the dealership and looked under a bunch of Tacomas and 4Runners and they all have transmission thermostats. The dealer didn’t have any sr5 models but I looked at TRD OR and a limited and they have thermostats. Did they forget to install one at the factory? Can anyone with a 4x4 sr5 take a look at theirs? Thank you


Mine

TRD OR

Toyota intentionally excludes the transmission thermostat on base SR5 models because they lack the additional external transmission cooling system found on higher trims like the TRD Off-Road and Limited.

 

[Burgi]

what do you mean pin the thermostat ?

if you want to check fluid level there is a start/shift procedure and the system will let you know when the fluid is warm enough but NOT 113degF or higher. if higher than 113F you cannot accurately set the level need to let it cool down and start over

toyota suggests you start at 68degF (cold basically) then if you do the below the D indicator will let you know when you can check the level with the standpipe in the drain plug hole

ADJUST AUTOMATIC TRANSMISSION FLUID TEMPERATURE (when Not Using the GTS)

NOTICE:

• Make sure to switch to automatic transmission fluid temperature detection mode within 60 seconds after starting the engine.
• At the automatic transmission fluid temperature detection mode, the D shift indicator illuminates for 5 seconds before it flashes when moving the shift lever to P or N if it is an appropriate temperature or higher.D Shift Indicator at Automatic Transmission Fluid Temperature Detection Mode
  

  	Below Automatic Transmission Fluid Level Adjustment Temperature	Automatic Transmission Fluid Level Adjustment Temperature	Above Automatic Transmission Fluid Level Adjustment Temperature
  Automatic Transmission Fluid Temperature (GTS Display Temperature)	35°C or less (95°F or less)	35 to 45°C (95 to 113°F)	45°C or more (113°F or more)
  D Shift Indicator	OFF	ON	Blinks

again, a drain and fill is done cold. you only need it barely warmed up under certain
circumstances. if you drain more than 50% the fluid you need a TON more done

---
How to get into fluid temperature detection mode ? a shifter dance


(a) Turn the ignition switch off. [#2]

(b) Depress and hold the brake pedal.

(c) Start the engine.

NOTICE:

To reduce load, make sure that all electrical systems, such as the air conditioning and audio system are off.

(d) Slowly move the shift lever from P to S, from S to 1st, and then back to P.

HINT:

• Keep the shift position in each position for approximately 3 seconds.
• Slowly move the shift lever to circulate the automatic transmission fluid through each part of the automatic transmission assembly.
  
  
  

• (e) From the shift position in D, move the shift lever between N and D within 1.5 seconds for 12 seconds or more continuously to switch to automatic transmission fluid temperature detection mode. NOTICE: Do not pause for more than 1.5 seconds. HINT: The automatic transmission fluid temperature detection mode will be activated by moving the shift lever between N and D within 1.5 seconds for 12 seconds or more continuously.

  *a Shift Position *b Indication of Shift Position *c Automatic Transmission Fluid Temperature Detection Mode *d 12 sec. or more *e 2 sec. *f Less than 1.5 sec.

  (f) Check that the D shift indicator comes on for 2 seconds and then turns off.

on all Toyotas when equipped with a transmission thermostat you need to pin it when checking/adjusting the level.

 

[AZGOLD]

If it is under warranty, why are you even messing with it

 

[127.0.0.1]

on all Toyotas when equipped with a transmission thermostat you need to pin it when checking/adjusting the level.

that info is direct from TIS on any trim, 2025 2026 4runner

 

[MStarmer]

26 ORP, no thermostat.

 

[Burgi]

If it is under warranty, why are you even messing with it

because the dealership was absolutely useless and offered no help. I ended up selling the truck almost a year ago so no more worries now.

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