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EJ20T Radiator fan runs constantly


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'93 Legacy Wagon

Like I said : radiator fan runs constantly.

 

The temperature gauge always gets to (and stays) at normal.

 

I read some posts about yuccky connection to the temp sensor at top front of block and sure enough mine looks pretty rough but seems to work OK.

 

Fluid levels OK and no leaks.

 

Am I missing something? Is there yet another temp sensor I'm not aware of?

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the ECU electrical connectors for D-check mode (diagnostic check) are probably connected. These are the connections up under the dash, near the ECU. probably 1 green single wire connectors, or 1 black single wire connector. disconnect them.

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the ECU electrical connectors for D-check mode (diagnostic check) are probably connected. These are the connections up under the dash, near the ECU. probably 1 green single wire connectors, or 1 black single wire connector. disconnect them.

Hi. Thanks. Will check but problem appeared without my interfering with the ECU connectors.

Have a gremlin maybe :rolleyes:

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wasn't a SUB but had a similar problem on a Tempo -

 

turned out the temp "switch" on the block failed shut and the relay stayed "on" and the fan ran continuously.

 

you might check the relay too - there has to be one somewhere. usually they don't fail "engaged" but it happens

I have a Subie CD of tech publications and had a good gander through it looking for just such a relay.

If there is one I cannot find it :(

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'93 Legacy Wagon

Like I said : radiator fan runs constantly.

 

The temperature gauge always gets to (and stays) at normal.

 

I read some posts about yuccky connection to the temp sensor at top front of block and sure enough mine looks pretty rough but seems to work OK.

 

Fluid levels OK and no leaks.

 

Am I missing something? Is there yet another temp sensor I'm not aware of?

 

First, If you looked at asensor on the top front of the block, you were looking at the oil pressure sender.

 

There are indeed 2 temp sender. 1 for the gauge, one for the ECU. They are both on the back side of the engine installed into the crossovertube. Below and a bit to one side of the throttlebody.

 

The single connector one is for the gauge.

 

The one with 2 connections is the one for the ECU, and the one that controls fan function. Test it for resistance, should change smoothly with engine temperature. If it has zero or infinite resistance it's shot. If it fails, the ECU turns the fans on as a failsafe.

 

Also, by chance, Sorry if this is dumb ? But you don't have you're Defrost or Air Conditioning on do you? That will make the fan run any time they are on.

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