Anyone know how the coolant temp gauge works?

Does anyone know the actual signal that goes from the ecu to the gauge cluster on a 1grfe truck? I can tell you that both wires that go to the coolant sensor connect to the ecu and then its a one wire connection to the Cluster. Im trying to figure out how to drive the gauge with just the sensor alone....If its even possible. Its one of the last features i'm trying to figure out how to make work. thanks for any help.

 

Unsure of this exact application, but in general, the sensor just varies the voltage that is sent to the gauge. The gauge is then "calibrated" to rise or fall based on that voltage. But if it going through the ecu first, the ecu could be sending a different voltage to the gauge to get it to read the right temp.

 

yeah see thats what im curious about is how i can if even possible make the sensor standalone with the gauge...it may not be possible without some kind of converter box though...

 

Im pretty sure there were changes at one point from the early trucks to the later trucks (12+) as the 12+ now operate the temp gauge via canbus. Earlier trucks I think they did it directly from the sensor via analog, A poke into wiring diagrams will let you know this.

Question is what are you trying to accomplish OP?

 

why not just get an aftermarket gauge. what are you trying to do here...

 

Simplest solution to add a temperature gauge is to just run a Scangauge or any other OBD2 active reader that can read the temperature directly from the ECU. Not sure why you'd want to run an analogue gauge for temperature off the stock sensor, it won't be a simple process and no guarantees it'll give an accurate result. If you're really sold on a dedicated gauge, just cut the upper radiator hose and insert a water temperature joint pipe to hold the sensor that will come with your gauge. $20 in parts and the upper hose carries the hottest fluid awayfrom the engine anyways.

 

There is a discrepancy between 05-11 trucks and 2012+ trucks and the way they operate indeed. @JustDSM believes the canbus broadcast signal ID is different between earlier and later gen models as my coolant gauge currently does not work. I am using a workaround to that by using an AEM 30-0311gauge which obtains it's coolant signal direct from the PCMs OBD2 link.

OP, it's best not to mess with the gauge honestly unless you have in depth experience and knowledge in CAN networks.

 

lol I can personally say by the time that needle moves the coolant is already boiling

 

A digital or analog aftermarket gauge is a good investment to have on these trucks then. I always did hate how our coolant gauges are sort of a dummy gauge. They definitely don't read the temperature right like the vehicles of yesteryear actually did.

 

yup almost all "temp gauges" on vehicles these days have a vague zone where the needle doesnt move much between 175-220* as this is normal operating temps. Then the gauge will move quickly above and below that!

Still definitely curious as to the OPs needs.

 

I’m just trying to get the temp gauge to work, it just bothers me that it sits at zero. I have a very accurate readout from hp tuners in my laptop of actual temp, and I’m putting a UltraGauge in for a permanent readout... it’s really just a looks thing that bugs me. But I can say at least the 06 cluster is not canbus. It’s a signal from the ecu on one wire directly just for coolant. Just wasn’t sure if anyone knew what that signal was. Anyone local got a truck I can test with? Lol, figure if I remove the cluster and check voltage coming to the cluster I can at least determine the range the stock gauge runs off of while an engine is running and warming up.

 

I would test myself but my engine is here
not in the truck so...lol

 

I hear ya. The looks thing bugs me too, but if you are getting a readout from the PCM, nothing has been previously modified, and the gauge is at zero then I am going to presume that you have a bad cluster and the only way around that is either repairing the dead stepper motor or replacing the gauge assembly as a whole.

 

oh things have been heavily modified...

 

I'm guessing the cluster itself might be where the signal is turned dummy. Companies made the decision time ago to make all pressure and temperature gauges useless in the name of reducing idiot service visits. Most of my family worked for GM at one point and dealers were tired of people coming in because they felt the gauge was slightly off without even knowing what they were looking at.

 

'12+ trucks are have the cluster temp gauge displayed directly from the CAN BUS. '05-'11 trucks have an analog output from the ECU to the cluster.

 

Paste an orange "needle" halfway, get an OBD device and $5 pro app to see the actual temperature. I see you're getting Scangauge, that should do it. The needle stays the same from 170°F to well into the 220's. Like an earlier poster said, if the needle moves, it's already too late.
What bugs me, and if you have a modified engine should bug you too, is no oil temperature sensor.

 

Now it all makes sense.

Want to race?

Its not oil temp he should be worried about in that LS engine, it's oil pressure.

 

I'd take either one, preferably both.

There is the oil pressure idiot light. About as helpful as that coolant temp gauge...

 

Oh whelp.... ya, uh, you win.