Hi speed cooling fan trouble

[Brett_jjj]

My Hi speed circuit on the cooling fan wont work,the low speed one works though.It comes on with the AC,it comes on at half way like usual when sitting idling,but when I unplug the temp sensor wiring from the temp sensor it wont go from lo speed to high speed like it should,it just stays on low speed.It should(once disconnected) after 12 seconds turn on to low speed,then after around 6 seconds go to hi speed.I have swapped relays etc,no difference,checked the engine fan fusible link,all ok.I connected 12 volts to the fan,tried it on both pins in the plug and it worked fine.This one has me stuffed,am I missing something.

[RX25SE]

Relay clicking when it tries to cut in?

Are you getting temp readings and fan relay status from the tech 1?
Can the tech1 do and actuation test?

I've seen a bad earth near the battery, the one on the inner guard, preventing the hi fan from coming on.

[Brett_jjj]

No relay noise at all.The Tech 1 was how I found out it wasnt working.It just commands the lo and hi speed fans on or off.Temp readings are fine.The lo speed works fine,just no hi.I will check out the earth youve mentioned and see what I find.

[Brett_jjj]

Well, no difference.The earth is clean and tight,I loosened it and tightened it again just to be sure of a good contact.Still no hi speed.Battery terminals are also clean.The Tech 1 cartridge I have has no menus for fan relay status.Just fan on or off.Hi or lo.

[hako]

Maybe you have a problem with your cooling fan motor or the wiring to the motor/relays - when the A/C comes on it switches the high fan on according to the manual. You say that it switches the fan to low??? When you hotwired the fan did it work at 2 speeds? (you dont specifically mention this).
I know these 2 speed fans wear out because my wrecker removes them from the wrecks and stores them in the office.

[Brett_jjj]

It just sounds like its on low speed all the time.(usually fairly noisy on hi speed)Even when hotwired it didnt seem to change much which I just put down to the way Id connected it to the battery,(used thin little wires as jumpers),but the two different terminals in the fan plug both worked.I might get another fan and try it.I thought the AC turned the low speed fan on ,maybe its just going to hi and not lo.Althought when I connected up the tech 1 and command fan on/off, it turns the low speed on,but wont turn the hi speed on.

[hako]

What happens when you pull the hi or lo speed relay out?

[Brett_jjj]

I will go and try it.

[Brett_jjj]

I started the engine and removed the lo speed relay,nothing,so replaced that,and removed the bigger hi speed relay,nothing,so I removed them both,nothing at all.Not even on at low speed.I gave it a while with each relay removed too.I know it was working a month or two ago,It was going from lo to hi no problem when the sensor wiring was removed,and nothing has been stuffed around with at all.Nothing has been touched.

[hako]

I reckon it's that Tech 1 you bought off Ebay...get rid of it....to me.
Fusible links?

[Brett_jjj]

The gregorys says that the lo fan is controlled by the BCM and ECM and the Hi speed controlled solely by the ECU.That explains why theres a low speed fan test in the BCM menu on the tech 1 as well as in the engine /ECU menu.Im gonna try another fan motor in the morning ,see what that shows.Checked the fusible links all ok. Thanks for the help fellas,I will post how I get on with another fan motor.

[Cheap6]

You might like to try the tests I suggested in a recent post in VT-VX. VS and VT/VX are very similar in how the fans operate.

Both Cooling Fan's Not Running? Help

[Brett_jjj]

Thanks ,will try that.

[admir87]

when aircon is switched ON, only the low speed fan is turned ON...
also low speed fan will turn on when the coolant temp sensor detects 104C

then low speed will switch off once coolant gets to below 99C

high speed only comes on if coolant temp ever gets to over 110C

low speed is controlled by the ecu, which gives a signal to the bcm to turn the relay ON
high speed is controlled solely by the ecu.

get yourself some jumper wire, disconnect the fan connector and connect the low speed straight onto the battery and an earth for the negative on the connector. make sure that low speed comes on

as for the high speed, you need 12v to both low and high speed on the connector and an earth for both negative connectors ( you cant just put 12v on the high speed side of the connector, it doesnt work like that). See if high speed works

once you rule out the fan motor go to the high speed relay, swap it for a spare,(pretty sure the highbeam or heater or something is the same relay as the high speed fan) once you swap it, disconnect the coolant sensor plug and see if low speed then high speed kick in now

then it could be anything from ecu to coolant sensor

sorry for the ramble

[Brett_jjj]

I will retest the fan like you have said with both terminals getting the 12 volts,and the other 2 earthed ,I did one at a time and it didnt look like the fan changed speed,now I know why. Thanks heaps to everyone for all the help,will post what I find out tomorrow.

[Cheap6]

as for the high speed, you need 12v to both low and high speed on the connector and an earth for both negative connectors ( you cant just put 12v on the high speed side of the connector, it doesnt work like that).

With the low speed fan relay (5 pin) in place, both high and low speed windings will be switched by the high speed fan relay. That's why the 5 pin relay is used (and why I suggested it be in place when testing).

[Brett_jjj]

Following Cheap6's link I tried to jumper the larger relay pin socket no's 87 and 30.Nothing, except the ignition stays on when the key is turned off.Triple checked the pin numbers and connections, all ok.And when I connected the large relay pin no 86 to earth ,sparks showered everywhere.I hope it hasnt fried anything,also the small (5 pin)relay is numbered from 1 to 5 not 86, 87 etc,so I left it alone not knowing what each terminal is for I didnt jumper anything on it.I tried connecting both terminals on the fan connector to 12 volts and both earths,When one live wire is removed it drops to lo speed, so the 2 speeds are working,although it does a fair bit of sparking when the jumper wires are connected/disconnected to the pins.The jumper wires I used are fairly heavy gauge and they were getting hot when the fan was running.Im going to get another fan later so I can try it,I will post what I find.I dont want to take it to an auto electrician,most of em just like to bypass the original wiring and relays and run new wiring and relays etc,which makes a mess of the wiring in my opinion.Id rather have the original stuff fixed.

[admir87]

ye the sparks are normal from when you connect the motor on both terminals, happened to me too....
so your fan is fine....

have you replaced your high speed relay?

and when you pull the connector off the coolant sensor, are you getting 12v to the high speed relay?

[Brett_jjj]

Theres 12v available to pin sockets 86 and 30 with the key on, on the hi speed relay.With key off there is 12 v available at pin socket 30 only.
The small lo speed relay has 12v available at pin sockets 5 and 1 with key on,and 12 v available at pin socket 5 only with key off.I havent had a chance to check the voltages available at the pin sockets when the sensor wiring is removed and engine running.Will do that in the morning.I checked the hi speed fan relay terminal sockets though whilst commanding the hi fan on and off with the tech 1 and there was no difference to any voltages on any pin sockets.
******** me picked up a spare VN fan today instead of the VS one I have,I didnt even take any notice of it being different until I got back into town.I will go get the VS one in the morning.But today the fan was working on 2 speeds when I used jumpers to test it though,so it might not be that anyway.Ive also tried about 5 different large hi speed relays, and swapped over the small lo speed relays,same same.The Tech 1 says that the BCM and ECU/PCM are commanding Hi fan on,so I just dont know.This one has got me stuffed.It might be a job for a holden stealer er dealer.

[admir87]

i got a feeling that there is no need for the high speed fan to come on at all, thats why its not switching on (the temp isnt getting over 110C )

once you do the, engine running and disconect the temp sensor connector, test, you will see if both are working.... low speed switches on, then a couple seconds later high speed switches on.

[Brett_jjj]

Ive already tried removing the temp sensor wiring with the engine running a few times now for the test you mention,the fan starts as normal after approx 12 seconds ,but doesnt change to hi speed like its meant to approx 6 seconds later.I just dont know,Ive used different relays,the fan works on both speeds when jumpered to the battery,theres no fuses or fusible links blown,the fan switches on with the AC no worries,and also switches on when temp gauge gets to half,which is normal for it to do.and no wiring has been disconnected or tampered with.And lastly when the fan is commanded on with a tech 1 the low fan speed works,but the hi fan speed doesnt.

[Cheap6]

If instead of connecting a jumper wire from the 86 pins to earth you use a test light or voltmeter you will be able to see if the switching side is OK or not. There should be battery voltage at the 86 pins with the relays not being switched by the PCM or BCM, ignition on for high speed, no voltage with them switched via either Tech 1 or fooling the coolant temp input.

If the voltage drops with the switching, the fault is on the switched side (or in the relay but you've already checked that by swapping it).

If the 86 pin voltage at the relay doesn't drop, look for the voltage (+ drop) at the PCM terminal. If it's got the voltage but not the drop it's in the PCM. No voltage is a broken wire.

If you need to ID the 5 pin relay pins, 30-87a has continuity across it (open circuit when switched), 30-87 is open circuit (closed circuit when switched), 85-86 should have a resistance of ~75 ohms or so. Pin 85 is the one with power to it (to differentiate between 85 and 86).

Theres 12v available to pin sockets 86 and 30 with the key on, on the hi speed relay.With key off there is 12 v available at pin socket 30 only.

If there is power to the 30 terminal on the high speed then jumping that to the 87 terminal should turn the high speed on. If not then the wire from the 87 terminal is not reaching earth. That should be spliced into the same wire that earths the low speed winding so the fault would be between the splice and the relay terminal (the low speed switching works).

[Brett_jjj]

Thanks mate, Im going to have another go at it this morning,some lowlife knocked off the spare VS fan I had,so I cant check that,although this one Im using showed up fine when jumpered to the battery.

[Brett_jjj]

The terminal 86 has 12v available with the hi speed off,when hi speed is commanded on nothing changes with terminal 86,it stays at 12v.

[admir87]

one of the terminals always has 12v, its the constant, with engine on

that might be the 86

its the signal terminal that will get 12v when the fan is commanded to come on, but dont know without looking which terminal it is