COOLING FANS connection

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mintcat
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COOLING FANS connection

Post by mintcat »

After installing EJ205 from JDM Forester SF5 there were some problems left, and one of them - make SUB FAN working.
As I understand: 99-00 Forester, like 98-00 WRX's has two 2-speed fans and their ECU's have two pins for 4 relays - 2 MAIN FAN and 2 SUB FAN relays, it switches ON both main and sub fans relays #1 (1 speed of fans) when coolant reaches certain temperature, then enables relays #2 when speed of the vehicle is insuffitient for effective cooling and both fans start working at 2 speed.

here's the scheme
Image

But according to service manual first gen Legacy's have only 1 pin for switching only 1 FAN at only 1 speed.
FAN switches to 2nd speed only when A/C tells it to.
Image

Right now I've made custom radiator diffuser and mounted 2 single-speed fans, and tired of thinking how to connect it :(
mintcat
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Re: COOLING FANS connection

Post by mintcat »

Ok, I got something.
Just have drawn the scheme.
Seems like ECU in BC/BF Legacy really operates only 1 speed of both fans. 2 speed is controlled by A/C only.
Image
Legacy777
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Re: COOLING FANS connection

Post by Legacy777 »

It looks like you have this sorted out, but just to throw in additional comment the second speed on the fans is tied into the pressure (trinary) switch of the AC system. This is the switch that screws into the AC receiver drier. So depending on if you still have AC or not that second speed could work or you could manually wire up a switch if you really wanted that extra cooling.
Josh

surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT

If you need to get a hold of me please email me rather then pm
mintcat
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Re: COOLING FANS connection

Post by mintcat »

I've wired EJ205 ECU FAN1 wire to fan control relay, as it was in stock setup in this Legacy, so ECU starts both fans when it needs to. FAN2 pin on ECU left not connected. But now there's one problem left - when temperature reaches some point ECU starts both fans (those aftermarket fans are single speed btw), and doesn't swithes them off, while engine is running. I have to stop the engine and wait for 3-5 mins for coolant temperature drop, and ECU doesn't switch 'em ON.

PS: ECU keeps fans ON even when thermostat is closed and radiator is really cold. Temperature gauge shows normal temperature, there's no any overheatings. Water pump is new and the thermostat too. Today I've replaced coolant temperature sensor, but problem persists. Some people recommend to install 10-30 Ohm resistor in coolant sensor line to ECU - it will make ECU switch fans with temperature higher (for 2-6 'C) than default.

I haven't yet install OBD connector to ECUs harness, so there's no way to read sensors data with K-line adapter right now.
Legacy777
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Re: COOLING FANS connection

Post by Legacy777 »

Can you provide a little detail on your setup? Do you have a vehicle speed sensor input to the ECU? If not that could cause the fans to stay on.

I wouldn't recommend using a resistor to alter the coolant sensor as that can cause a lot more issues. Before you do anything more, install the OBD II connector so you can check the ECU for codes and look at the data/switches. I am curious to see what the ECU thinks the coolant temp sensor is and if it's really calling for the second speed fan control to come on.
Josh

surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT

If you need to get a hold of me please email me rather then pm
mintcat
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Re: COOLING FANS connection

Post by mintcat »

This car initially was Legacy BC2, FWD, EJ18S SPFI.

Setup:
Engine - JDM EJ205 (240hp) with wasted spark ignition, 550cc stock injectors. TD04L turbo. ECU 22611AE831. Wiring harness integrated into stock Legacy's harness. NPS and VSS connected properly, speedo gauge (cable driven) not working, because I have 3pin VSS connected to the ECU, so it's not a problem right now, there is a plan to install 3rd gen legacy comb.meter.
Tranny - TY754VBBBA, 4.11 ratio (taken from 3rd gen Legacy). Rear Diff (marked JP) - 4.11 ratio with simple viscous lsd.
Main radiator - brand new aftermarket 30mm radiator.
FANS - two single speed high perfomance aftermarket fans with custom hand made aluminium diffuser, fAN1 - connected to speed1 main fan and FAN2 - to speed1 sub fan. ECU turns them on simultaneously because I left stock legacy's fan control scheme, where both of the fan relays are connected together and wired to "FAN1 RELAY" ECU pin , so "FAN2 relay" pin on that ECU is not used.
Car has no Air Conditioner, because of ex-owner decision to get rid of it.

I suggest that heater core is clogged, because the air from the heater feels slightly warm (not hot:(), unlike my other subies heater. So I'll try first to flush heater core, and if no result - to replace it ASAP. It's possibly the reason why hot coolant is not circulating properly and stays in water tube under intake manifold and ECU thinks that engine is going to overheat.
But water temp gauge on comb.meter panel says OK, pointer is in the middle and never goes higher. It's strange, because coolant sensor is combined type (3-pin sensor) so it measures temperature for both ecu and gauge.

ECU has no errors in memory, CEL - working properly, but didn't ever blink. Idle is little unstable, but I assume that's because of dirty injectors and old spark plug cords, I didn't check TPS voltage yet, will do it tomorrow.

PS: recently I swapped heater core hoses, because they were initially connected contrariwise, and coolant was flowing in wrong direction through the heater core. Now feels little better, but problem persists. I've replaced coolant sensor too, but it didn't help.
Legacy777
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Re: COOLING FANS connection

Post by Legacy777 »

Does the engine have one coolant temp sensor or two, one for the dash and one for the ECU?

How do you have the VSS output connected to the ECU? Did you tee into the existing wire or did you cut the existing wire and connect the VSS output to it?

Do you have a scan tool or some other device to read/view the ECU parameters? I'm assuming that ECU has OBD2 communications so if you can verify some of the parameters with a scan tool that would tell you what the coolant temp readings it sees are as well as confirming the VSS readings are working.
Josh

surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT

If you need to get a hold of me please email me rather then pm
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