patrick335d

Hi guys.

I got a question and i think i came to the right spot, there should be bright minds here.
i got an GMPP LS376/525 in my truck, with the original ECU and harness.

I have a big CBR radiator with 2 x 25 amp Spal fans.
the blue wire actuates 2 x 40A ralays in parallel to supply the fans.
Now the thing is that the fans come on at the standard value 207F, then pull the temperature down all the way to 150F and dont stop.
only way to stop the fans is to kill the motor and restart it.

Shouldn't be there a switchoff level eg 180F or is the output configured for a frequency drive or PWM?

thanks.

Project GatTagO

iTrader: (7)

Are you using the GMPP harness and E67 ECU? If so, that set-up just cycles the fans on/off. I would double check your wiring. As I recall the ECU provides a ground trigger to the relays. Maybe they are grounding on something else and keeping the fans on?

Regardless, I don't see how even if the fans stayed on the temp would drop to 150 degrees. The thermostat (if stock) is 187 degrees and would shut the water flow through the engine.


Andrew

patrick335d

yep i have the original ECU and harness p/n 19259261.
in the fusebox of the harness there is a 20A output for the cooling fan, blue wire.
i never seen fuses on a ground.
anyway the gm manual is limited on info.
first i thought that is installed too light relays and that the contact remained sticking due to the high current. but now with 40A relays it remains the same.

thermostat is 165, engine only is this temperatures on idle. engine is used on a lot of wot with relative low vehicle speed. and pre running in a hot desert.

patrick335d

I had the HP Tuners on, I can switch on and off the fans in the Scanner, under the VCM controls. they switch on and off, so it isnt the relays sticking.
I lowered the starting point, but it still does the same.
the fans start running at 190F and will keep running till i Kill the engine.

any thoughts?

Russ K

iTrader: (1)

Post your tune, and I'll take a look at it.

Russ Kemp