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Dualxeon64

Engine fans don't turn on mr2link tst185

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Which model car is this in? The sw20's factory wiring has the radiator fans controlled independently from the ecu - non AC models its just a temp switch in the radiator, AC models its a temp sensor that feeds back to the AC module and this controls the rad fans.

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Its a 91 toyota mr2 turbo model. The fans work and come on fine when I put the factory ecu in but the only time they come on with the link ecu is when I turn on the AC now.

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On the 185 ECU we have no outputs wired for Fan control, As we are expecting them to be controlled as per cj's response above.

Can you confirm if they are actually wired back to the ECU?

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How are you testing this? If its by switching the AC on, thats likely because the "AC is active" signal from the ECU isnt getting back to the AC computer (AC amplifier in the toyota manuals), so the AC amp probably isnt turning on the fans in response.

There are no wires directly from the ECU to any rad cooling system. 

The only wires from the AC amp to any engine related systems are:

(on 3sgte's)

1)AC Amp receives a tacho signal from the ignitor. It uses this to disable ECU above a certain rpm, so this has no impact on cooling fan behaviour.

2)ECU receives an input signal from the AC clutch relay so it knows then the AC amp has turned on the AC clutch.

(on non turbo's)

1) ACT signal from ECU to AC amp when grounded disables AC - ie at high RPM

2) ACA signal from AC amp to ECU to tell the ECU when AC is active (for idle control) - pretty sure it grounds it when AC is active

 

Best guess... you have the ACT pin grounded because of a config in the LinkECU, and you are testing the fans by turning AC on. In this scenario, the AV wont actually turn on and so the fans probably wont either.

At idle it can take quite a long time to get the radiator up to temp to have the fans come on normally. If you want to force a test, mess with the water temp sensor in the radiator - either pull it out and put it in boiling water while still connected (if you can block up the hole), or disconnect the sensor and it should turn the fans on (if that fails, try shorting the pins instead).

 

 

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