1SLwLS1

iTrader: (6)

The other day I finally got around to doing the fan switch mod and wired up my LED's to the center console and switch under the dash. To the best of my knowledge, the PCM hasn't been modified to turns the fans on at a lower temp, but that may be something tuners do?

To the question, is this post accurate? I am going to ASSuME that the PCM derives the coolant temperature from the sensor in the head. My logs show that the temperature never gets above 212*F in the summer heat, which shouldn't even trigger the low fans. I have that switch mounted to the passenger rear port and an Autometer unit reading the driver side head port. They are within 5*F of each other.

So, is it safe to assume the A/C pressure is what is always triggering the fans, outside the DTCs? I have also turned the AC off while cruising down the road when the fans were on (A/C off about 2 minutes) and they didn't turn down to low or off. I figured that with 2 minutes of 70 MPH cool air rushing over the condenser, it would of dropped the pressure beneath the cutoff point, but maybe not.

joecar

Depending on your year/model, that post is true if your PCM has not had the fan temperatures edited (fans low speed turn on temp; fans high speed turn on temp).

Yes, from ECT sensor at front of driver side head.

Yes, if your cooling system is in good condition the fan trigger temperatures may not be reached.

AC pressure triggers fans only if AC is being requested and AC refrigerant pressure meets trigger point... i.e. with AC off the fans will not be on due to AC, but for some other reason.

You need a scantool to see what ECT sensor is reporting, this is what the PCM is using to decide if fans should be turned on.

1SLwLS1

iTrader: (6)

Well then, my trigger temperatures must of been edited then as I have used my phone and my laptop to verify the temperatures as well as taken several logs. I guess I need to pony and purchase the REAL editing software to get more information

ssduane

iTrader: (3)

any chance the fans are just spinning enough to power the LED light to iluminate? I've heard of this before, if the LED is directly wired to the fans and not grounded off the relay to control fans.

joecar

It seems like alot of money now, but you will not regret it at all

1SLwLS1

iTrader: (6)

No, they only get a signal if the PCM signal wires are grounded.

The list of expensive stuff never stops