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The problem is the fans do not turn on and off automatically. I suppose the ECU or the radiator control module is supposed to activate the relay for the radiator fan and another question when the radiator fan turns on, the condenser fan is supposed to turn on as well, correct? When I put the the radiator fan directly on the relay it turns on, but the condenser fan doesnt. Could it possibly be because the condenser fan relay is bad that would cause radiator fan not to come on? My main concern is where is ECT switch A supposed to go? on the intake? Somebody who had this car cut off the blue/red wire and black wire, but I do not know the reason for that. Would that be the reason why the radiator fan wont turn on? My last guess would be the radiator fan control module.
Re: Where is ECT Switch A blue/red wire on prelude 93
Originally Posted by ross2004
Switch A is at the thermostat housing, and that's what controls the radiator fan. All it does it pass ground through to the radiator fan relay.
I suppose there is 4 sensors? since its labeled ECT switch A, and did not know where it went, I decided to connect it with ECT switch B. But my main problem is the condenser fan does not turn on, just the radiator fan. Are they supposed to turn on at the same time? I am using direct power to radiator because I believe the radiator module does not activate the relay and it will only turn on the radiator fan. Until my alternative radiator fan relay and sensor comes, I will use that instead.
Re: Where is ECT Switch A blue/red wire on prelude 93
With the ignition to ON or START, if the coolant temperature is above 199 degrees F (or 203 degrees F for H22A1) at engine coolant temperature switch A (located on the thermostat housing – connected to the lower radiator hose), then the switch will close, which should turn on both cooling fans (radiator fan and A/C condenser fan).
With the car running, if the A/C is turned on, both cooling fans should run, regardless of the coolant temperature at the Switch A.
When you shut off the car and the coolant temperature is above 223 degrees F at the engine coolant temperature switch B (located on the housing connected to the upper radiator hose ), the radiator fan will run until the temperature drops at Switch B (which opens the switch) or up to ~ 15 minutes.
Both Switch A and B are normally open type of switches, and close when the coolant temperature is above the respective temperatures.
If you were to disconnect the 2P connector to the coolant temperature Switch A, and jump the connector with a piece of wire or small paper clip, then turn ignition to ON (II); both fans should run.
Re: Where is ECT Switch A blue/red wire on prelude 93
Originally Posted by tech8
With the ignition to ON or START, if the coolant temperature is above 199 degrees F (or 203 degrees F for H22A1) at engine coolant temperature switch A (located on the thermostat housing – connected to the lower radiator hose), then the switch will close, which should turn on both cooling fans (radiator fan and A/C condenser fan).
With the car running, if the A/C is turned on, both cooling fans should run, regardless of the coolant temperature at the Switch A.
When you shut off the car and the coolant temperature is above 223 degrees F at the engine coolant temperature switch B (located on the housing connected to the upper radiator hose ), the radiator fan will run until the temperature drops at Switch B (which opens the switch) or up to ~ 15 minutes.
Both Switch A and B are normally open type of switches, and close when the coolant temperature is above the respective temperatures.
If you were to disconnect the 2P connector to the coolant temperature Switch A, and jump the connector with a piece of wire or small paper clip, then turn ignition to ON (II); both fans should run.
So youre telling me if I jump the 2P on ECT switch and the radiator fans dont turn on I might have an open to what is connect to the lower radiator hose? I tried that and they did not turn on. I havent checked if they even have power, I havent jumped ECT switch B yet. But I did try the fan switch and nothing happened. However if I jump the relay location it does turn on, thats why I believe something is not turning on the relay and I tried a known working relay and it did not work either. What else could it be if its not the sensors fault? I dont see where ECT switch A goes yet, but you said its supposed to turn on without it. Again, only the radiator fan will turn on. On the first pic I took, from what im understanding is that, that is where its supposed to go, but there is already one there. So maybe its somewhere near there?
Re: Where is ECT Switch A blue/red wire on prelude 93
Re-read tech8's post, it's about as clear as it can be said. If the previous owner was in there cutting up wires, who knows what the problem truly is. Follow the lower radiator hose to where it meets the engine in the rear. That's the thermostat housing, Switch A is threaded into it. Here's an easy way to check if it's working or not if you have a multimeter: engine cold, there should be no continuity across the two pins. Once the engine is hot, 199/203F, the internal switch closes and you should then have continuity. If you don't, you'd got a bad sensor. If you do, now it's time to start tracing the wiring and seeing what's really going on.
Re: Where is ECT Switch A blue/red wire on prelude 93
If you jumped the disconnected 2P connector to Fan Switch A with the ignition turned to ON, and the fans do not run, that means there is an Open (break) in the circuit.
You need to understand the circuit and do various testing on the wires to narrow down the cause(s).
Look at the circuit diagram you posted. This is an example of part of the fan circuit:
The radiator fan relay has four terminals with four separate wires connected to it.
The relay has a coil that gets energized when power (+) is applied on the Yellow wire from the Radiator Fan Control Module and Ground (-) from the Blu/Red wire coming from Fan Switch A. If you jump the 2P connector for Fan Switch A, ground suppose to come through the black wire and then through the Blu/Red wire.
When the relay coil is energized, it closes the switch (think of it like a draw
bridge) and allows power (+) from Under-hood Fuse No. 47 through the relay to the radiator fan motor.
Things you would have to check:
Is Under-hood Fuse No. 47 okay? Is power going through to that relay terminal in the fuse box?
Is there power on the Yel wire from the Radiator Fan Control Module with the ignition turned On?
Is there Ground continuity on the Blk wire and Blu/Red wire?
is there Ground continuity on the radiator fan motor’s ground wire?
Re: Where is ECT Switch A blue/red wire on prelude 93
start with simply unpugging the fan switch A connector and turn the ignition to on and stick a paperclip in the connector, see if that turns the fans on
Re: Where is ECT Switch A blue/red wire on prelude 93
Ok just to clarify, on the pic 1 that shows the thermostat housing. If that is not the blue/red wire, are you saying that, that connector connected to that sensor does not go there? I dont see where there would another sensor on that theremostat housing, unless it is the one showing on the pic 1.
Re: Where is ECT Switch A blue/red wire on prelude 93
You took really crappy pictures... so I am taking a shot on the wire colors plugged into the sensors that you have asked about. It appears that you have a grey 2 wire plug plugged into the fan switch at the thermostat housing (first pic)... with a green wire and a red wire. If this is so, that is plugged into the WRONG location. It should be plugged into the ECT sensor which is found under the distributor. You have another grey 2 wire plug already plugged into the ECT sensor (second pic)... it appears to have a white or yellow wire and a blue/red stripe wire taped into it. This plug should be plugged into the fan switch at the thermostat housing. As a test, you should be able to bend a paper clip into a "U" shape and connect the two pins of this plug while the key is on and the fan should come on.
For future reference, it would be in your best interest to offer up clear pics of what you are asking about WITH a description of the wire colors of the plug in question so that you can get help more efficiently. Also, if the plugs wiring shows any signs of being altered, spliced or replaced... specify this so that those trying to help may offer additional information or ask you to test continuity on the wires.
Re: Where is ECT Switch A blue/red wire on prelude 93
Ok, I plugged in the blue/red and black wire to that thermostat housing. And it appears that somebody adapted the wrong wires to it. It was using a yellow and Green/Black wire. Does anybody know where these two would go? Also I tried jumping the blue/red and black wire together and it did not turn on. Im starting to think that the fan module is not allowing the sensors to close. I forgot to mention, I am turning the car on with a button switch because it wont crank.
Re: Where is ECT Switch A blue/red wire on prelude 93
Originally Posted by tech8
If you jumped the disconnected 2P connector to Fan Switch A with the ignition turned to ON, and the fans do not run, that means there is an Open (break) in the circuit.
You need to understand the circuit and do various testing on the wires to narrow down the cause(s).
Look at the circuit diagram you posted. This is an example of part of the fan circuit:
The radiator fan relay has four terminals with four separate wires connected to it.
The relay has a coil that gets energized when power (+) is applied on the Yellow wire from the Radiator Fan Control Module and Ground (-) from the Blu/Red wire coming from Fan Switch A. If you jump the 2P connector for Fan Switch A, ground suppose to come through the black wire and then through the Blu/Red wire.
When the relay coil is energized, it closes the switch (think of it like a draw
bridge) and allows power (+) from Under-hood Fuse No. 47 through the relay to the radiator fan motor.
Things you would have to check:
Is Under-hood Fuse No. 47 okay? Is power going through to that relay terminal in the fuse box?
Is there power on the Yel wire from the Radiator Fan Control Module with the ignition turned On?
Is there Ground continuity on the Blk wire and Blu/Red wire?
is there Ground continuity on the radiator fan motor’s ground wire?
Fuse #47 has power on both legs. But I tried continuity from fuse 47 to the first leg terminal on the relay and didn't get continuity.
I also check the Blk wire and it does have ground continuity and the Blu/Red wire has continuity to the Third terminal and the Fourth terminal reads about 300. So maybe, a bad fuse box?
The way I look at the relay terminal:
1 2
3 4
*Update: I checked for continuity from fuse 47 to terminal 2 and it has continuity.
I haven't checked the radiator module, is there anyway to check if it has power without having to take it off. I believe its hard to get to? The only thing I can think of is that the radiator fan module is not getting power from the ignition. Also, checked ground continuity on radiator fan and it does have ground.
Re: Where is ECT Switch A blue/red wire on prelude 93
1. Is there power coming into the relay terminal via the Yel wire with the ignition turned On?
2. The radiator fan control module is located under the passenger foot-well carpet, next to the ECM.
Re: Where is ECT Switch A blue/red wire on prelude 93
Originally Posted by tech8
1. Is there power coming into the relay terminal via the Yel wire with the ignition turned On?
2. The radiator fan control module is located under the passenger foot-well carpet, next to the ECM.
I believe yellow wire would be the first terminal, and no there is no power in that terminal. And I would have to check the yellow wire from the fan control module tomorrow.
Re: Where is ECT Switch A blue/red wire on prelude 93
The yellow wire and green/black wire are likely the reverse light switch pair. It seems obvious at this point that you have some wiring demons, so you are going to need quality wiring diagrams and start checking continuity between the ECU and each plug on the engine itself to verify proper sensor connection.
As for the fan, I would unplug the two wire connector right at the fan motor itself and connect two temporary wires to it and touch the two individual wires to the terminals on the battery directly. If the fan spins up, you will have to begin to work back from there. Finding the correct fan switch plug will help diagnose the fan control issue as well.
Re: Where is ECT Switch A blue/red wire on prelude 93
I found something interesting on the main relay, somebody tried to put ground on the black wire on the main relay. I took it off, because I believe that is for fuel pump not ground. And here is the pic:
Black - 0.1v Blu/Red - Ground Green/Black - 10v
Yellow - Ground Blk/Yel -10v Yel/Blk - 10v Yel/White - 10v
I found this website for the wiring diagram for the prelude 93: https://rusefi.com/wiki/index.php?ti...a_Prelude_1993
*Update: I checked continuity from ECU pin 12 to the white/green cable on fan module and no continuity for some reason. It does have 5v on pin 12 though. Also, there is continuity from the yellow wire on the fan module to the terminal 1 on the relay.
Re: Where is ECT Switch A blue/red wire on prelude 93
The Wht/Grn wire at terminal no. 6 of the radiator fan control module suppose to always be Hot (have power), power comes from under-hood Fuse No. 45 (15A). -- There is an issue there is you only have 3 volts on that wire.
Blk/Yel wire at terminal no. 2 should have power with ignition ON.
Blk/Yel wire at terminal no. 7 should have power with ignition ON/
Re: Where is ECT Switch A blue/red wire on prelude 93
Originally Posted by tech8
The wires that suppose to have power at the radiator fan control module should be approximately 12 volts.
I was looking at one of Daniel Sullivan's video and the only thing I can think of is that I have an open somewhere in that circuit. I gave the car back to the owner, he will just be running with direct power on his fans. Im just curious what could have caused the voltage drop.
10-26-2017, 02:43 PM
Where is ECT Switch A blue/red wire on prelude 93
