Vn V6 thermo fan not working

[merlinsteve]

Hi all.
I have a very annoying and strange problem.
My thermo fan stopped working and the car almost overheated. I stopped and waited. when the car was cool I went on and I heard the fan come on.
2 days later it did it again.
I have replaced the temp sensor with a new one. I tested the relay and it works.
Fuse is ok
I manually tripped the fan from the connector and that worked.
Did the same from the relay connector. All good.
Tripped the coil side or the relay and Yep the fan works.
Going through the manual I worked my way back to the computer.
Back probing the connectors I could see the resistance of the temp sensor and it was changing as the car warmed up.
I disconnected the computer connectors and using a wire from the battery manually tripped the fan from the computer connector. so I KNOW the wiring is ok between the 2.
So according to the manual it is either bad connections or the computer.
fast forward to a month later and I install a second hand but tested computer (with MY memcal) and still no thermo fan.
I am going to physically remove and dress all the connectors but like I said before the thing ran from the computer connector so there is a circuit there.
Any suggestions would be appreciated as I can't afford to go and pay someone to fix it for me.
Thanks
Steve

 

[merlinsteve]

anyone with any ideas???


Please!

 

[holden_89]

mate best thing to do ive found with my own and alot of mates with the fan just bypass the fuse and relay and re-do the wiring from ya fan to a switch. this is a common problem with alot of commodores, apparently its got something to do with a fault in the thermostat. been told by a few mechanics just wire a fuse and switch along the positive and earth the other end. takes like 10mins. when ya car starts to heat up hit the switch then when its cool turn it off simple =p

 

[304runner]

anyone with any ideas???


Please!

Yeah I have an idea...Use the search bar the forums supply's you!

 

[merlinsteve]

Hers an idea, I tried the search engine first and nothing acceptable.
I don't want to bypass something I want to FIX it.
hence asking the question of a forum where hopefully someone would have an idea. I know it is easy to bypass and thanks holden_89 for the suggestions as they are helpful in band aiding the situation and can get me moving whiles I actually fix the problem.
but as this seems to be a common problem I thought that shock horror someone might have actually gone looking for it and fixed the issue and could say have you tried XYZ. that would be helpful even if it doesn't fix the issue it eliminates something and then in future when someone does search the forums there is some things to try.

heres what I have tried in fault finding.
I can back probe the ECU and trigger the fan from there. I have replaced the ECU just in case.
I can manually switch the relay from a lead from the battery.
I have connected a variable resistor to the temp wiring and changed the resistance in the hope of triggering the fan. this didn't work from the temp sensor wiring OR by back probing the computer with it so I don't think it is the sensor, it is new anyway so most likely not.

I have looked through the manual and found that the power for the switched side of the relay comes through the heater circuit. the heater doesn't work so maybe they are related? I have to go and check.
so I ask again does anyone have any ideas about where I could look or check?

 

[DieselBob]

Try the A/C when you switch it on it should trigger the fan relay.
If it does its a problem on the engine side.
Might be a problem with the MEMCAL if you've got a spare try that too.