2007 Columbia low air warning won’t go off.

After stopping for the day, I started the truck back up to run the microwave and when I did, the low air light and warning chime would not go off. The air pressure is good. So are the switches in the manifold behind the trashcan.

Does anyone have a schematic for the low air circuit and how it’s tied in with the AC?

 

It is infuriating to try to find a wiring schematic online. You have to sift through a gazillion spammer link farms to find anything useful.

Does anyone here own a Columbia of any year and have access to DTNS Connect?

 

Yep, that’s basically it, minus the park brake cutout switches.

The primary and secondary low air warning switches themselves are good. Closed above 60 psi... I checked them with an ohmmeter.

From what I gather, and I haven’t been able to find a schematic, those two switches control ground to a circuit leading directly back to the ICU. The strange thing however, when the switch is open, there is about 1.5v less than battery voltage on one wire—about 12.3 volts. As soon as the switch closes, it falls to zero.

Along with this problem I have a code 146 sid 11 fm 5 that showed up at the same time. As well as my scan gauge intermittently showing no data.

While checking the switches, I saw Qualcom wiring under there that was just cut and laying loose. I’m thinking that may be problem—data wires that are shorting on something.

 

I’m guessing a 3?? It’s an ‘07. How would I tell the difference?

 

Ok, so mine is an ICU3.