First place to start would be to hook up a scan tool to check for DTC'S - diagnostic trouble codes an viewing input data ( parameters ) from the coolant temp sensor to the PCM / ECM - engine computer ,the computer energizes the cooling fan relay to turn on the fan. , then view wiring diagrams to see what all is involved in the cooling fan (s) electrical circuits an testing the electrical circuits with a DVOM - digital volt ohmmeter . Not sure what plug your talking about , no plug i know of . Unless they mean the the socket the fan relay plug's into . There are video's on youtube on how to check from the socket the relay plug's into. Two battery power supply's , one control from the Engine computer , an one load (fan) . If you pull the relay out of the fuse / relay box an look on the bottom side of the relay you will see four numbers , 30 - 87 an 85 - 86 . Pin 30 has battery voltage , pin 87 goes to the fan . If you take a piece of 12 gage wire an jump pin 30 to 87 if the fan is good it should turn on . Pin's 85 & 86 are the control side of the relay , one of these should have battery voltage an the other goes to the ECM - engine computer , the ECM when it see's high temps from the coolant temp. sensor it supply's a ground to that circuit energizing the relay to turn on the cooling fan. Which engine does your car have ? 2.2 or 2.0 L the 2.0 l has two relays an two cooling fans .
Cooling Fan Control 2.2L (L61)
The engine cooling fan system consists of one cooling fan and one relay. The relay is powered by the battery positive voltage circuit and controlled by a switched ground from the engine control module (ECM).
During operation, the ECM supplies the ground path for the cooling fan relay through the cooling fan relay control circuit. This energizes the cooling fan relay coil, closes the relay contacts, and supplies battery positive voltage from the cooling fan fuse through the cooling fan motor supply voltage circuit to the cooling fan. The cooling fan motor is grounded through its own ground circuit.
The ECM commands the fan on under the following conditions:
• Engine coolant temperature exceeds approximately 106°C (223°F).
• A/C refrigerant pressure exceeds 1310 kPa (190 psi).
• A/C is requested and vehicle speed is below 100 km/h (62 mph) with A/C pressure above 1413 kPa (205 psi).
• AF23-5 Transmission fluid temperature exceeds 130°C (266°F).
• VT25-E Transmission fluid temperature exceeds 140°C (284°F).
• When the engine coolant temperature exceeds 100°C (212°F) at key off, the fan will run for up to 108 seconds.
The ECM commands the fan off under the following conditions:
• Engine coolant temperature drops below approximately 100°C (212°F).
• Throttle position is greater than 95%.
• Vehicle speed exceeds 113 km/h (70 mph)
Cooling Fan Control 2.0L (LSJ)
The engine cooling fan system consists of 2 electrical cooling fans and 3 fan relays. The relays are arranged in a series/parallel configuration that allows the powertrain control module (PCM) to operate both fans together at low or high speeds. The cooling fans and fan relays receive battery positive voltage from the underhood junction block. The ground path is provided at G105.
During low speed operation, the PCM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. This energizes the cooling fan 1 relay coil, closes the relay contacts, and supplies battery positive voltage from the cool fan 1 fuse through the cooling fan motor supply voltage circuit to the left cooling fan. The ground path for the left cooling fan is through the cooling fan s/p relay and the right cooling fan. The result is a series circuit with both fans running at low speed.
During high speed operation the PCM supplies the ground path for the cooling fan 1 relay through the low speed cooling fan relay control circuit. After a 3-second delay, the PCM supplies a ground path for the cooling fan 2 relay and the cooling fan s/p relay through the high speed cooling fan relay control circuit. This energizes the cooling fan s/p relay coil, closes the relay contacts, and provides a ground path for the left cooling fan. At the same time the cooling fan 2 relay coil is energized closing the relay contacts and provides battery positive voltage from the cool fan 2 fuse on the cooling fan motor supply voltage circuit to the right cooling fan. During high speed fan operation, both engine cooling fans have their own ground path. The result is a parallel circuit with both fans running at high speed.
The PCM commands Low Speed Fans on under the following conditions:
• Engine coolant temperature exceeds approximately 106°C (223°F).
• A/C refrigerant pressure exceeds 1310 kPa (190 psi).
• After the vehicle is shut off if the engine coolant temperature at key-off is greater than 140°C (284°F) and system voltage is more than 12 volts. The fans will stay on for approximately 3 minutes.
The PCM commands High Speed Fans on under the following conditions:
• Engine coolant temperature reaches 110°C (230°F).
• A/C refrigerant pressure exceeds 1655 kPa (240 psi).
• When certain DTCs set.
When the request for fan activation is withdrawn, the fan may not turn OFF until the ignition switch is moved to the OFF position or the vehicle speed exceeds approximately 10 mph. This is to prevent a fan from cycling ON and OFF excessively at idle.
https://www.youtube.com/watch?v=Mru8BbTGDwM&t=327s
Get a multi- meter so you can test the fan and coolant sensor
SOURCE: 1990 miata cooling fan and a/c fan
a multimeter is good but can give you a false reading . i would check with a test light first
SOURCE: Cooling fan wont work
The water temp sensor is located near the thermostat housing. This sensor is what tells the ECM to turn the fan on/off. The water temp sending unit is located near the same area. You know you have the correct sensor is because the water temp sensor has a 2 prong plug. The water temp sending unit only has 1 prong.
SOURCE: cooling fan won't come on.
HI. I have prepared some steps for you to follow.This will aid you will the troubleshooting.
Step1
Check for broken wires or loose connectors around the fan circuit.
Inspect connectors at the fan motor, relay, sensor or heat sensitive
switch, and the Electronic Control Module (ECM)--your car’s computer
control system. Also, make sure to check for a possible blown fan fuse.
These are common and overlooked troublesome spots that may cause a fan
to fail.
Step2
Run and bring the engine to warm temperature. With the engine running, use a voltage test light to check for power
to the motor fan. Be extra careful and make sure to keep your hands and
tools away from the belt, fan or any other engine moving parts. If
voltage is reaching the fan motor, the test light should glow.
Step3
Turn off the engine after you see the light glow. Apply direct voltage to the fan motor from your car
battery using a pair of spare wires. If the fan fails to operate,
replace the fan motor. If the motor operates, your problem is in the
motor connector.
Step4
Locate the heat-sensitive switch or heating sensor if the fan motor
operates with direct voltage and the test light did not glow. You
should find the sensor in the radiator, engine block, or thermostat
housing.
Step5
Measure the resistance across the heating sensor with the multimeter.
With the engine at cool temperature (engine off), it should register
infinite resistance; with the engine at warm temperature (engine off),
you should read low resistance. If both readings state infinite
resistance install a new heating sensor, that’s the cause of your
failing fan.
Step6
Check the action of the fan relay if the heating sensor is registering
variable resistance. Your service manual should specify the power and
ground wires according to color codes and the proper way to test it. If
the fan relay fails the test replace it with a new one.
Step7
Check the connections going to the ECM after you determine the fan
relay is working properly. If you find broken wires or loose
connectors, make the necessary repairs. If you suspect a defective ECM
take your vehicle
to a service shop for a computer analysis. In most cases, the ECM is
rare to be the cause of a failing fan. The above steps should take you
to the root cause of your problem and help you fix the cooler fan.
Please rate and god bless..
where is the cooling fan relay located on a 92 taurus
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