The only way they turn off is to disconnect 12v battery or remove Fan #2 relay (removing #1 or #3 they still both stay on) If the battery is connected and Fan #2 (5pin) relay are both connected both fans will stay on until the battery dies The relay is good and I even swapped out for a couple others I know to be good. Would the coolant temp sensor be the next place to start? Would seem odd if that were the case with no key in the ignition but I'm not super familiar with these cars. Also, engine coolant temp reading on scanner is reading correctly. There are no codes or any other issues with the car, its a 2003
Thanks, still not making a ton of sense considering both fans are staying on with the key out. Maybe you can see something I'm missing?
Power to the radiator fan relay on most newer vehicle (Prius) comes directly of the battery positive. All is needed is a ground for the relay to activate the radiator fan motor. There is three plus possibilities for that power to also be supplied to the condenser fan in the event of component or circuit failure. Your are looking for a circuit ground allowing one or both of these control relays to close. It could be either a circuit ground (wire) or a control component (sensor or switch) within the grounding circuit to complete the ground circuit. I am pressed for time now, but will look at the wiring diagram this PM to see if I can be any further help. Later, Peace.
Odd, considering your drawing shows that if Relay 3 is removed then there is NO current path for the AC fan (A1) to run. Any way, Normal line up as shown in static drawing: Neither fan is running until water temp switch makes up. Once water temp switch makes up, relay 3 closes, placing 12v power to fans A1 and R1 (which show to be in series), causing both fans to run on what I would imagine to be low speed (each will drop ~6v). If AC Pressure switch A3 shuts, it energizes relay 2 and 1. When Relay 2 shifts contacts, it cuts off fan R1 and connects fan A1 directly to ground so it will run at full speed (12v). Relay 1 shuts and applies full 12v power to fan R1 so R1 now runs at full speed. So item one would be are the fans running at full speed or half speed? If both fans are still running even when relay 1 is removed, then power has to be coming from Relay 3. Yet, if relay 3 is removed and both fans keep running, it's not possible per the drawing as Relay 3 is the sole source of power for fan A1. If both fans stop only after relay 2 is removed, this would be due to relay 2 interrupting the current flow patch that is only used when relay 3 is shut for slow speed operation of both fans. Relay 3 is only shut when the temperature switch is closed or something else is grounding out that wire, simulating the switch being made up. The only things in that circuit are wires and the AC amplifier I have to admit that I'm a bit curious if the drawing is labeled correctly.
I was a bit puzzled by it too but it is the correct diagram for all Gen1 Prius as far as I know. Gen2s are much different. I can remove relay 1 and 3 at the same time, as long as 2 is in both fans will run. I haven't had the car for long but I do believe it is full speed, I ran the car for a while with the AC on and the speed never changed. I even took out the 2 30A fuses (RDI and CDS) and the fans still run. Starting to think it may be the ECU....could a bad AC pressure switch or Temp sensor even cause the fans to run constantly with the key out?
TMR-JWAP - I agree, something is mis-labeled or the routing on the drawing is not totally correct. Without relay 3 grounded via the temp switch, the condenser fan will not run (as depicted). Something else is the path to ground. System wiring integrity needs verified via voltage and voltage drop checks. I might suggest removing Relay 3 and check for power at pin 3 receptacle in the box with relay removed, should be zero. Possible power short across pins 5 and 3 (or other source of power to pin 3) would allow current flow to A1 and through Relay 2 (in unactivated condition) to operate R1. Although I think that would take out the 30A CDS fuse, anything is possible. Just looking for something outside the box. PS- What is the operation of the AC amplifier. Does it control fan speed?
I think the drawing is labeled correctly. For factory wiring anyway, if not always for wiring as 'modified' by collisions, rodents, or hurried mechanics. Any recent history of collision or repair work around the front of the car? When the fans are running and the key is off, what are the voltages to ground at A1 pin 2, A1 pin 1, R1 pin 2, and R1 pin 1? -Chap
