Peterbilt 387 no guages

Hello

I purchased 2007 Peterbilt 387 with C15. The primary air buzzer stays on and the air pressure stays at zero. There is NO air leak anywhere. I changed the primary air gauge on the dash and still the same issue. I also changed the pressure switch which is located inside the dash still not working. Anyone had this issue before? Thank you

 

few questions, let’s get them out of the way. Even if they seem Obvious.
Do you actually have air? I am assuming so but that is important. Both sides? Primary and secondary?

Also should be a set of tanks under the passenger and driver cab mounted on the frame check them for air just in case. That is important because there is a back flow air diaphragm valve that if it’s stuck might be the culprit but usually not.

lastly underneath the truck the box that gets all the information is next to the transmission on the drivers side. Mine is anyways. I would check there also. Usually it’s not gauge when it’s electronic in my experience. Usually it’s information to or from the brain to the gauge.

I am not familiar with the air pressure switch under the dash. Unless you mean tractor trailer release valves or buttons.

 

Thank you Chris. Primary and secondary air tanks are full. I was told it might be the low pressure sensor which is in this picture that I have attached. The sensor that hooks up to this valve under the cab next to the green hose. PART#830-0005-000. I will check underneath the truck the box that gets all the information also. Thank you

 

No worries. Also it’s about the size of a large phone and has about 3 air fittings going into it. Inside the frame rail.

 

The pressure switch on the tractor protection valve under the cab is the brake light switch on 387.

Ditto on the interface module as suspect problem with the gauges. Check power to it as well.

 

I changed the brake light switch which is inside the dash.