Change thermo fan on/off temperature

[emilebos]

Hi all,

Am looking to lower my factory thermo fan on/off temperature settings on an LS1 02 WH Caprice. At present fan 1 comes on at 107c, would like to drop this down to 97c along the lines of what my LS1 VU ute has had set for years and works a treat.

Have an 82c thermostat fitted to both.

Wondering what software applications are available to make the change? Have heard of the HP Tuners application, but it’s sooo pricey!!! Guessing there should be other software or app options available to edit fan temp settings, does anyone have more info on how to do this?

[R8HSVHRT]

Just go to a local tuner easy fix

[emilebos]

Just go to a local tuner easy fix

Haha, yes, that would be the easy option, but I’d rather work through this and learn how to edit the tune myself.

And it’s all sorted now! Further researched a cost effective solution and ordered in an OBDX Pro GT dongle and connected it to the PCM via the free software application ‘PCM Hammer’. All good so far, downloaded and saved the factory tune to a .bin file, and will edit and write back the updated tune later this week by using another free software application ‘Universal Patcher’ :woot:

[emilebos]

Hi all, need some tips on what to check next. Have an 02 WH Caprice LS1. I’ve had it a few months now and am currently working through sorting out why my cooling fans are not engaging at the low speed setting at idle? They do come on at stage 2 at around 108c but not at stage 1 which should be around 98c if I compare to what my 02 VU SS is doing.

I’ve read the PCM tune which is factory std, and find the low speed fan setting is in there with a 98c trigger, as is the stage 108c trigger, but the fans are not coming on at 98c? Both fans clearly work as the stage 2 trigger confirms this. Have swapped out the low speed fan relay and replaced the fans 30A engine bay fuse, but still no joy??

So have basically run out of ideas based on my limited experience, so hopefully you guys can help out with some tips on what else needs checking.

https://i.imgur.com/IZxpnWG.jpg

https://i.imgur.com/fJQ06LE.jpg

[duke5700]

Low speed goes through the BCM. The BCM puts negative on the coil for the low speed relay as per the workshop manual. It works with VCM Suite/HP Tuners as far as variable configuration. As an example, mine is set at 92°C and off at 88°C for first stage.

You will need more nuanced information from PCM Hammer forum, possibly on Fakebook these days. Forums are going the way of the dodo.

[emilebos]

Would never have guessed the BCM plays a part in the low speed fan settings. Don’t really know much about the BCM, is it programmable like the PCM?

Read some more about this on the US forum LS1tech.com, seems a few ppl are asking why BCM as well..

https://ls1tech.com/forums/conversions-swaps/1368314-cooling-fan-wiring-question-anyone-who-has-used-ls1-holden.html

[duke5700]

It is all done via the PCM I believe as far as Low/High Speed for the fans. It must do it over the comms bus between the two. I've not looked into it. BCM is done by Tech2 mostly.

Based on that thread you linked, it suggests that the BCM must respond to the PCM saying that the negative has been closed for the high speed fans to work. In any case this sounds like you've an issue with a negative somewhere.

I would set the low speed fans to ON via the scanner (if you have it, otherwise set the low speed fans to 80°C) then check for continuity to the negative on the negative side of the relay. There is a constant 12V supplied to the positive side of the coil. So should see 12VDC+ on the BCM side of the control relay until the negative is switched, then you should see 0VDC.