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1991 Corolla DLX 4AFE, 1994 Camry LE 5SFE, 1995 Avalon XLS 1MZFE, 2004 Sienna XLE/LTD, 2011 Camry LE
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Toyota refers to these coolant temperature sensors in a variety of ways but the one on the radiator is often referred to as
WATER TEMP. SW (FOR COOLING FAN) in most of their 5SFE schematics, and ENGINE COOLANT TEMP. SENSOR (WATER TEMP. SENSOR) (FOR COOLING FAN) on the 1MZ-FE V6 engines. These sensors are used to switch the radiator fan and condenser fans ON/OFF when the coolant temperature reaches a certain temperature, approximately 190 deg F.
 

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Discussion Starter #3
Another question.

When I unplug that connector and the fans come on, then is the sensor connected to the radiator at fault?
Because my fans do not work at all when it is connected to that sensor.
 

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Another question.

When I unplug that connector and the fans come on, then is the sensor connected to the radiator at fault?
Because my fans do not work at all when it is connected to that sensor.
Not necessarily - only if your coolant temperature is already above ~190 deg F would that seem logical. I'm not positive but the 2000 V6 Camrys had the hydraulic fan control, so you have some extra components in that system that complicate matters somewhat, such as a Cooling Fan ECU feeding to the ECM. Just be careful or you might possibly fry some computer circuitry. The E5 fan control switch on the Camry V6 is similar to the Avalon V6's, that is to say the E5 Fan control sensor was up on top of the engine by the front cylinder bank valve cover. That's the switch that usually fails because there is much more heat on the top of the engine - I'll include the location diagram and schematic to help you. Bear in mind this schematic and component location guide are for a 1992-1996 Camry, but your 2000 should be pretty close.
329561
329562
 

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Not necessarily - only if your coolant temperature is already above ~190 deg F would that seem logical.
My understanding is fan should always turn on when rad temp switch is disconnected - assuming relay is operating.
 

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THE COOLING FAN ECU RECEIVES VARIOUS SIGNAL, I.E., THE ENGINE RPM SIGNAL FROM THE IGNITER, COOLANT TEMPERATURE SIGNAL FROM THE ENGINE COOLANT TEMP. SENSOR (WATER TEMP. SENSOR), A/C REFRIGERANT PRESSURE SIGNAL FROM A/C SINGLE PRESSURE SW.

THE COOLING FAN ECU JUDGES THE ENGINE BASED ON SIGNALS FROM ABOVE MENTION, DRIVES THE SOLENOID VALVE AND CONTROLS THE SPEED OF THE COOLING FAN STEPLESSLY

FAIL–SAFE FUNCTION:
WHEN THE MALFANCTION IS DETECTED BY THE ENGINE COOLANT TEMP. SENSOR (WATER TEMP. SENSOR) OR SOLENOID VALVE, THE FAIL–SAFE FUNCTION OF THE COOLING FAN ECU JUDGES THE SITUATION TO ALLOWS THE COOLING SYSTEM TO CONTINUE OPERATION.
 

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A 2 A/C SINGLE PRESSURE SW:
2–3 : OPEN ABOVE APPROX. 15.58KG/CM2 (221.2PSI, 1527KPA)
CLOSED BELOW APPROX. 12.56 KG/CM2 (178.4PSI, 1231KPA)

C14 COOLING FAN ECU:
1–GROUND : APPROX. 12 VOLTS WITH THE IGNITION SW ON

9–10 : 2.5 VOLTS AT 20°C (68°F) AND IGNITION SW ON
1.2 VOLTS AT 80°C (176°F) AND IGNITION SW ON

8– 4 : 10–14 VOLTS AT A/C PRESSURE SW ON (OPEN)
0–3 VOLTS AT A/C PRESSURE SW OFF (CLOSE)

4–GROUND : ALWAYS CONTINUITY

E 5 ENGINE COOLANT TEMP. SENSOR (WATER TEMP. SENSOR) (FOR COOLING FAN):
1–2 : 1.5K AT 80°C (176°F)
0.7K AT 110°C (230°F)
 

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My understanding is fan should always turn on when rad temp switch is disconnected - assuming relay is operating.
So yes, disconnecting the E5 sensor (on the top of the engine - V6) should allow the fans to run continuously in fail-safe mode, if there are no other faults present in the Radiator/Condensor Fans circuitry. So daochoua inquiring about the sensor on the bottom of the radiator (on V6 model) is most likely the dashboard temp sensor for the dash indicator gauge, and the ECT sensor would feed the EFI/ECM computer for air/fuel ratio computations. I don't have the schematics for the 2000 V6 Camry, this is just from memory from years past, troubleshooting Avalons and Camrys from the 90's. Somebody might wanna double check me on this, but I'd check the E5 sensor on top of the engine. It's a thermistor and they do go bad occasionally, the nominal readings are in my post above.
 

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Discussion Starter #11
My understanding is fan should always turn on when rad temp switch is disconnected - assuming relay is operating.
Yes it runs when I disconnect the rad temp switch.
I replaced the part with a new one. The fans work now when AC is turned on.
Still have an overheating issue. What else could it be? The thermostat sensor?
 

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Yes it runs when I disconnect the rad temp switch.
I replaced the part with a new one. The fans work now when AC is turned on.
Still have an overheating issue. What else could it be? The thermostat sensor?
Replace the thermostat, if it's not opening you will get overheating. Also check for coolant leaks around the radiator cap and expansion tank (black plastic tank on top of aluminum fins), as well as the cooling fins. Replace the radiator cap if it does not operate within the parameters for normal operation. You can pressure check your radiator system, or maybe one of the autoparts stores will lend you the pressure tester and information on how to use it safely and correctly. NEVER work on a hot engine/radiator!
 

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Discussion Starter #13
Replace the thermostat, if it's not opening you will get overheating. Also check for coolant leaks around the radiator cap and expansion tank (black plastic tank on top of aluminum fins), as well as the cooling fins. Replace the radiator cap if it does not operate within the parameters for normal operation. You can pressure check your radiator system, or maybe one of the autoparts stores will lend you the pressure tester and information on how to use it safely and correctly. NEVER work on a hot engine/radiator!
I replaced thermostat. No leaks around the radiator cap since I too bought a new radiator cap. I'll just have to get the pressure check tester and see if it leaks anywhere.
 
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