CTIS Principles of Operation

[Russ Knight]

Is there a document (TM or otherwise) here that someone can link me to regarding exactly how the CTIS system works? I've read there is a speed signal generator attached to the transfer case. Could that perhaps be used to supply a speed signal to a cruise control module?

Russ

 

[Coffey1]

There is a over speed sensor.

 

[Coffey1]

1. Start truck
2. When truck builds air to 120 psi a pressure switch will close
3.euc will command pcu to do a tire pressure check.
4.a pressure transducer will tell ecu what the pressure is in tires by converting pressure into a electrical single. Then ecu will command pcu to open supply valve or dump valve to meet setting on ecu.

5. Over speed sensor will command ecu to switch to correct pressure settings if speed goes above safe speed for tire pressure setting.

 

[74M35A2]

Above is correct. Additional is CTIS checks tire pressure every 15 minutes unless in run-flat mode, which then checks it every 15 seconds. Delivery lines are bled down to 0psi during normal driving as to not pressurize hub seals continuously. Wheel valves take air to inflate and deflate (strange but true).

Yes, one can use the speed sensor signal generator as input into a cruise control module. I don't think anybody has the pulses/mi decoded yet, have "heard" 29,999, but unsure. Not hard to do with a scope or even a hand held DVOM with Hz function. Drive 60mph (mile per minute), ready the freq, then do the simple math.

 

[Russ Knight]

What would be awesome would be a system with a set point that could monitor and control tire pressure. Wonder if that could be done via a small plc?


Sent from my iPhone using Tapatalk

 

[74M35A2]

That's what CTIS does.

 

[Russ Knight]

I mean a programmable set point. Also, if I wanted to install a pressure gauge in the cab, where is the best place to tap into the outgoing air supply?


Sent from my iPhone using Tapatalk

 

[74M35A2]

The factory 5 set points is a lot to begin with. You can change the factory set points, but we have not cracked it yet, these modules may be OTP (one-time-programmable), as we can't yet get the factory diag tool to communicate with them.

If you want more than that, easiest way is to do a manual valve control panel with gauges like several here have.

Yes, could also be done with a PLC.