High speed thermo fan

[4ONTHETREEVS]

Hi all. I have a VS 11 97 UTE V6 auto.
My high speed thermo fan kicks in as soon as the key is on. I've had the mechanic run the scan tool and confirmed the low speed fan is coming on at set temps as per Holden states.
The temp probs resistance changes as per manual says The high speed relay is getting a out put from the ecu.
I've swapped high and low relays with no change.
I've currently pulled the high speed relay out and just running on the low speed fan as normal.
Anything else I may have missed or you could suggest to check.
Thanks

 

[ephect]

Ecu Coolant temp sensor, the vs has two,
one is for the gauge which is 1 wire
One is for the ecu which is 2 wire, this is the one to check.

Check the plug is still connected, unplug and replug it. Turn ignition to reds to see if it's fixed it. If not, you may have to change it.

 

[woteva]

Just checking your AC is turned off ?

 

[gtrboyy]

Should only turn on if in limp mode,ac on or over certain temperature.

If no fault codes maybe something weird to do with ac like switch or wiring earthed out

 

[BlackVXGTS]

Have you displayed your error codes? Post up any codes that are displayed. I've also attached diagnostic charts from the Holden VS Service Manual. Not sure why there are three items. There may be some duplication but I haven't had the time to look at them.

Checking error codes VR/VS (Revised)

Checking your Computer for Faults (VR - VS) Locate the diagnostic connector under the the steering column on the drivers side. Grab a paper clip and bridge pins number 5 & 6 'black' and 'white with black stripes' respectively on the ALDL (Assembly Line Diagnostic Link) connected which are...

forums.justcommodores.com.au

 

[4ONTHETREEVS]

There isn't any codes coming up on the mechanics snap on scanner but It can read all the fuel trims, temps etc. Which he said temps are all normal and the low speed kicks in what Holden set it at. (With high speed relay removed).
I've tried with the ac button on and off but high speed fan runs as soon as the keys on.
The ac works as normal gets icy cold and does its cycles.
I know the temp gauges are not very accurate but it's never been over half even just running low speed.
There is a very new radiator in the ute and just a wild guess but I'm wondering if the previous owner had heat issues and some how maybe bridged some wiring to run the fan full speed all the time. is there a way to test that.

 

[Jolls]

Check the wiring to the sensor conector. If that has deteriorated due to heat it can cause a short there that makes the ECU think the temp is high and run the fan to cool it down even though there is no requirement. That is what I have experienced on the VY anyway.

Cheers n Beers
Jolls

 

[4ONTHETREEVS]

I'll check that next I had a look at the fuse block loom but it seems untouched and oem so I'll remove the engine cover and trace wires more likely to be effected from heat. I plugged the temp plug into a gm temp sender I have spare from my holley sniper kit and no difference but could be a short further back like you said.

 

[jeepster]

Unplug the engine coolant sensor. It is hard to get at under the serpentine belt and DFI module. If your multimeter has small probes, measure the voltage on the plug with ignition on. It should be 4.9 to 5 volts. If not, you have wiring harness fault.

 

[4ONTHETREEVS]

Unplug the engine coolant sensor. It is hard to get at under the serpentine belt and DFI module. If your multimeter has small probes, measure the voltage on the plug with ignition on. It should be 4.9 to 5 volts. If not, you have wiring harness fault.

Thanks mate I've just checked then and confirmed it has spot on 5.0v dc. At the plug pins.