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Hi speed cooling fan trouble

Brett_jjj

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Can anyone sugggest anything else I can try before I go buy another ECU,and can anyone confirm the above mentioned blue/white wire is meant to have, and stay at 5 volts when the hi fan is commanded on by the ECU.This problem is really pissin me off.Usually its just a faulty relay or bad connection that causes these sorts of problems but everything,(relays ,wiring etc). all checks out ok when tested
 

admir87

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hi mate, i'll get out my multimeter today and let you know what everythings meant to be on with no fans, and whats on with low/high
 

Cheap6

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Can anyone sugggest anything else I can try before I go buy another ECU,and can anyone confirm the above mentioned blue/white wire is meant to have, and stay at 5 volts when the hi fan is commanded on by the ECU.This problem is really pissin me off.Usually its just a faulty relay or bad connection that causes these sorts of problems but everything,(relays ,wiring etc). all checks out ok when tested

See what admir87 comes back with but the PCM should be switching the high speed fan relay pin 85 to earth. Power to pin 86 will be from the ignition switch. Convention - and the VT wiring diagram I have - says that 85 is the power and 86 the earth. It seems that they are swapped around in VS. No big deal except when checking the circuit: i.e. subsitute 85 for 86 and vice versa for the VT tests. I should have picked up on that when you were saying that the 86 pin has power with the ignition on.

If the blue/white wire is the correct one it should have zero volts at the PCM with the fan switched on (= PCM transistor switched to earth) and battery voltage with it off but ignition on and relay in place (open circuit in the PCM = PCM transistor not switched on). Sounds like it is the PCM but best to be sure.

Disconnecting the coolant temp. sensor throws a temp. sensor fault code and switches the fans on. The 68 ohms (100 ohms would probably do) resistor dummies in a signal equivalent to a coolant temp. high enough to switch both fans on = same thing. Using the Tech 1 will do the same thing. Any of the three methods to switch the fan will achieve the same result.
 

Brett_jjj

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Theres definitely 5v on the blue/white wire at the relay terminal 85 and doesnt change from 5v,its the
same when measured at the ECU on the blue/white wire.5v and doesnt change at all when the hi fan is commanded on,either with the tech 1 or by disconnecting the sensor wiring and starting the engine.I tried it both ways.No difference.It doesnt change to battery voltage at all either.Just constantly stays at 5 volts.
 

Brett_jjj

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Can someone please help me out and check out something on their car for me with a multimeter.I need to know what voltage terminal 85 on the hi speed cooling fan relay has, (the large relay),I need to know what the voltage is when the engine is off(key in on position,motor not running),and also with the engine running with the temp sensor wires removed(unplugged), and the cooling fan going at hi speed.(removing the temp sensor wires will start the low,then hi speed cooling fan.)I cant get on to the people I know that own VS's, so I cant check out another car,so any help would be appreciated.Thankyou.
 
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Ron41

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Brett, I am not to good with this stuff but I just checked mine, with ignition on motor not running I got 0.10 on 85 [ multi meter set 20 ohms ], took the coolant sensor wirring plug off started it but will not go to high speed with relay out, only with relay in, so can't test it mate.
 

Cheap6

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Brett, I am not to good with this stuff but I just checked mine, with ignition on motor not running I got 0.10 on 85 [ multi meter set 20 ohms ], took the coolant sensor wirring plug off started it but will not go to high speed with relay out, only with relay in, so can't test it mate.

He wants the voltage. Set the MM to 20V. You can check the voltage with the relay connected by partly lifting it out of the terminals.
 

admir87

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hi mate, sorry for the delay... ok checked mine, did 2 checks both with engine ON. one with engine fans off. the other one i disconncted the coolant temp sensor and waited for high speed to come ON.

first test with fans OFF,(at high speed relay connected)
pink black wire had 13v
orange wire had 13v
blue white wire had 13v
orange blue wire had 0v

with engine high speed fan ON(waited for it to kick in after disconnecting the temp sensor)
pink black wire had 13v
orange wire had 13v
blue white wire had -0.22v or 0.22v
orange blue wire had 13v


(for both tests both high and low relays are connected and working)
didnt have time to check what each one is but im sure you sorta figured it out by now
i'll check the low speed wires tommorow and let you know the same for it
 

Ron41

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It was on the 20 Volts scale [ buggered why I said ohms for ], I just lifted the relay and from 85 it read 0.4 to 0.5 going back and forward from those 2 numbers whilst the high fan was on.

I hope this helps Brett.
 
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