Cant turn off low coolant alarm LLM

[DuraBurb]

Well the title says it all, I have a Duramax in a SUV and for what ever reason GM has seen fit to wire the "low coolant" switch from the engine coolant resioir into the A/C control modual. Yep you read it right, the A/C head unit. If I swap the diesel dash for the gasser I still get the same alarm so I'm sure its comming from the engine, if I swap the a/c controler out then the alarm goes away but it wont support the rear a/c. Can't find the engine output for the alarm is there any way to get at it.

Eric

[ScarabEpic22]

Welcome to the site Eric, I took a look at your vids and site a few months ago. It would be sick having a 2500 Burb with a DMax inside! Better yet, an Escalade... :D

Are there any DTCs you can turn off? Im grasping at thin air here, if not then you might have to find out what resistance the A/C switch is expecting and install a resistor or something to fool the A/C module so it thinks the level's fine. Not the best way, but with swaps you have to get creative right?

Mind posting the tune, I cant take a peek til Sunday but it might help others track your problem down. Wonder what the boat swap guys are doing about this, Ross/Paul?

[GMC-2002-Dmax]

The sensor is probably a either normally closed and becomes open when the sensor reads low coolant or is normally closed and goes open.

See if you can "trick" it.

[DuraBurb]

The signal is just a ground return (bk/wh on one side of the NO switch and the return is lt gn) it goes back to the a/c controller of all things, go figure. The return signal goes to pin 14 on the j2 black plug. The only thing I can figure is GM did it to shut down the a/c in a low water condition via hard wire, but it doesn't exist on the gas engine. Seems odd to me.
I suppose the boat and other swappers dont worry about it because they dont likely use the stock dash and this is just an alarm not a DTC and doesn't throw a code. There isn't any tune on it, all stock less the antitheft. I also tried swapping the BCM for the P/U to test that notion and still got the alarm so now I know for sure it is coming from the ECU.
So in short, the a/c/ control modual takes the signal, acknowledges it and turns that into some sort of mysterious data sent over the buss to the ECU, if the signal is lost then the a/c controller dosent send that signal via the buss and then the ECU tells the DIC via the buss to alarm the message "COOLANT LEVEL LOW ADD COOLANT". Can the programmers of efilive give us access to the alarms as well as DTC's? Would that be a big deal?

Eric

[DURAtotheMAX]

eric why cant you just jumper the connector going to the low coolant level switch on the surge tank....?

[DuraBurb]

Hey Max, nice to see you here too. Actually it is hooked up and works fine if I use the P/U a/c controler (as it understands the input) but then you loose rear a/c because that modual is mechanialy different. I may have to do some cloning work, the EFILIVE programers said shutting off alarms is out of thier scope and cant help me. I don't know.

[ScarabEpic22]

Sounds like your only options is to figure out what resistance/voltage the AC controller wants to see from that sensor and mimic it. Anything but the ECM, PCM, or TCM is out of EFILive's scope Im afraid.

But hey, Ill take full tuning support and no BCM/etc controls. VW/Audis only get access BCM/rando modules with their VAG-COM hardware/software, no tuning support (unless you shell out big bucks for precanned stuff).

[DuraBurb]

Well the controller is seeing the right input it just dosent know to send notification out on the buss so the ECU can know weather or not there is a signal comming in. There is nothing to mimic since it is all hooked up and functioning. The folks at EFILive say they only work with DTC code stuff not alarms, so if I can't just shut off the alarm from the ECU I guess I'll have to hack the a/c control software and find a way to enable the feature, may-be with TechII.

[ScarabEpic22]

I know its working on the truck, but the ECM has no idea its working. Mimic the signal the ECM wants to see and it wont throw the alarm, if you want the alarm to function have it output to something aftermarket (no idea what sorry).

[DuraBurb]

Hmmm, mimic the o.k. signal from the a/c controller....
That just might work but who understands the communication protocol on the GM buss so I can figure out a way to create a data packet signal that should be coming from the a/c control module. Now theres a real mystery.

Eric

[ScarabEpic22]

Hmmm, mimic the o.k. signal from the a/c controller....
That just might work but who understands the communication protocol on the GM buss so I can figure out a way to create a data packet signal that should be coming from the a/c control module. Now theres a real mystery.

Eric

Very true, wish it was a dumb sensor that simply outputted a certain voltage and/or resistance that could be fixed with resistors/etc.

Thinking in a different direction, what happens when you use the p/u AC unit? No rear air support, does that mean nothing works or just AC doesnt work? Wonder if this would be easier to overcome?