tl;dr -
I used -40 to 320 as my range for everything, though apparently the sensor range is -40F to 419F according to the FSM. Using a lower value doesn't really hurt you, it just changes the range displayed (and limits the max value) - which can be helpful if you're using analog-style gauges in OBD Fusion). If you set it to -40F to 250F and the temp hits 260F I believe it will just continue to read 250F.
As far as alerts, I really don't worry until my A/T temp is over 240F, and even then I interpret the info below to mean Toyota doesn't get concerned until you're above 275F. Coolant temp I've never seen higher than maybe 215F. All of them will run 195-200F when you're in 4th gear cruising on the highway when towing, or when you're in 6th but not towing.
More details than you probably want...
The A/T system will apparently trigger the "A/T Temp" light if the "No 2 ATF Temperature Sensor" detects an ATF temp of 150C/302F. It will go off below 275F. I assume "No. 2 Sensor" as the FSM describes it is probably the "A/T Oil Temp 2" (which is somewhere in or after the torque converter). The trigger at 302F is why I chose 320F as my max value... it wasn't until right now that I saw 419F in the FSM
Side note: If the ATF temp >266F, the TC will actually lock-up in 3rd gear as well, not just gears 4-6. I also believe the vehicle will downshift you to 3rd (there's a "shift point too high" symptom). Recover is below 230F. I've never experienced it, just read it in the FSM - highest I've ever seen the TC was about 255F, which I saw going over one mountain pass this month. AT pan reached 238F for a short while.
From the FSM. Highlights in red are mine
DESCRIPTION
The Automatic Transmission Fluid (ATF) temperature sensor is on the transmission, just in front of the oil cooler inlet pipeline.
If the ECM detects an abnormally high ATF temperature near this sensor, it illuminates the warning light.
HINT:
- The temperature of ATF easily rises when towing, climbing hills, in traffic, etc.
- If the ATF temperature sensor becomes short-circuited, the signal that indicates that the ATF temperature is 150°C (302°F) or higher is input into the ECM.
Vehicle conditions when the sensor is normal and when the sensor is short-circuited are indicated in the table below.
| NO. 2 ATF TEMPERATURE SENSOR STATE | DETECTION CONDITION | SYMPTOM | RECOVERY CONDITION |
|---|
| Sensor is normal | ATF temperature higher than 150°C (302°F) | ATF temperature warning light remains on | ATF temperature below 135°C (275°F)*1 |
| ATF temperature higher than 130°C (266°F) | Shift point too high | ATF temperature below 110°C (230°F) | |
When conditions (a) and (b) are satisfied.
(a) ATF temperature higher than 130°C (266°F)
(b) Engine coolant temperature higher than 95°C (203°F) | Lock-up at 3rd gear*2 | ATF temperature below 110°C (230°F)*1 and engine coolant temperature higher than 95°C (203°F) | |
| Sensor is short-circuited | Any conditions |
- ATF temperature warning light blinks or message is displayed in combination meter
- Shift point too high
| Symptoms still occur |
| Engine coolant temperature higher than 95°C (203°F) | Lock-up at 3rd gear*2 | Symptoms still occur | |
HINT:
*1: When the ATF is normal, it decreases to below 135°C (275°F) within 5 minutes with the shift lever in P or N in an idling state.
*2: When the ATF temperature is normal, transmission lock-up occurs in 5th or 6th gear with the shift lever in D or with the S6 range selected, in 5th gear with the S5 range selected, and in 4th gear with the S4 range selected.
| DTC CODE | DTC DETECTION CONDITION | TROUBLE AREA |
|---|
| P2742 | The No. 2 ATF temperature sensor resistance is below 25 Ω (0.046 V) for 0.5 seconds or more (1-trip detection logic). |
- Short in No. 2 ATF temperature sensor circuit
- No. 1 transmission wire (No. 2 ATF temperature sensor)
- ECM
|
| P2743 | No. 2 ATF temperature sensor resistance is more than 156 kΩ for 0.5 seconds or more and either of the following conditions is met (1-trip detection logic): |
- Open in No. 2 ATF temperature sensor circuit
- No. 1 transmission wire (No. 2 ATF temperature sensor)
- ECM
|
| Condition (A) 15 minutes or more have elapsed after the engine start when engine coolant temperature or intake air temperature is -29.375°C (-20.875°F) or less. | | |
| Condition (B) 10 seconds or more have elapsed after the engine start when engine coolant temperature and intake air temperature are more than -29.375°C (- 20.875°F). | | |
MONITOR DESCRIPTION
The ATF temperature sensor converts the ATF temperature into an electrical resistance value. Based on the resistance, the ECM determines the ATF temperature, and the ECM detects an open or short in the ATF temperature circuit. If the resistance value of the ATF temperature is below 25 Ω*1 or higher than 156 kΩ*2, the ECM interprets this as a fault in the ATF sensor or wiring. The ECM stores a DTC, and the ATF temperature warning light blinks or a message is displayed in the combination meter.
HINT:
- *1: 150°C (302°F) or higher is indicated regardless of the actual ATF temperature.
- *2: -40°C (-40°F) is indicated regardless of the actual ATF temperature.
- The ATF temperature can be checked on the Techstream display.
WIRING DIAGRAM
Refer to DTC P0711 .
INSPECTION PROCEDURE
NOTICE:
Perform the universal trip to clear permanent DTCs .
1. DATA LIST
HINT:
Using the Techstream to read the Data List allows the values or states of switches, sensors, actuators and other items to be read without removing any parts. This non-intrusive inspection can be very useful because intermittent conditions or signals may be discovered before parts or wiring is disturbed. Reading the Data List information early in troubleshooting is one way to save diagnostic time.
NOTICE:
In the table below, the values listed under "Normal Condition" are reference values. Do not depend solely on these reference values when deciding whether a part is faulty or not.
(a) Warm up the engine.
(b) Turn the engine switch off.
(c) Connect the Techstream to the DLC3.
(d) Turn the engine switch on (IG).
(e) Turn the Techstream on.
(f) Enter the following menus: Powertrain / Engine and ECT / Data List.
(g) According to the display on the Techstream, read the Data List.
Engine and ECT
| TESTER DISPLAY | MEASUREMENT ITEM/RANGE | NORMAL CONDITION | DIAGNOSTIC NOTE |
|---|
| A/T Oil Temperature 2 | No. 2 ATF temperature sensor value/
Min.: -40°C (-40°F)
Max.: 215°C (419°F) |
- After stall test: Approximately 80°C (176°F)
- With engine cold: Equal to ambient temperature
| If the value is -40°C (-40°F) or 215°C (419°F), the No. 2 ATF temperature sensor circuit is open or shorted. |
HINT:
- When DTC P2742 is stored and the Techstream output is 150°C (302°F) or higher, there is a short circuit.
- When DTC P2743 is stored and the Techstream output is -40°C (-40°F), there is an open circuit.
Check the temperature displayed on the Techstream in order to check if a malfunction exists.
| TEMPERATURE DISPLAYED | MALFUNCTION |
|---|
| -40°C (-40°F) | Open circuit |
| 150°C (302°F) or higher | Short circuit |
