Ctis and ABs help please!?

[AzOutback]

Hey guys,

New to the forum, and fairly new to fmtvs
I just bought a 1088a1 and started having CTIS problems almost immediately. It would work some days and others the controller would just blink at me. I could unhook it and leave it off for a while, and it would go back to working as normal.
Lately, however I bought another CTIS controller and put it in. The first time I put it in it worked very well, but the second time I used it something, I assume a solenoid started smoking under the dash. Unplugged it and shut everything down, but could not find what was smoking. Since then, I’ve tried to use it, but all it does is either blink consistently, and the ABS light is on or it will try for a little bit and then the highway and run flat blink
Help please, I just need a place to start. I’ve never had to go further with the CTIS then replacing the controller on any of my LM TVs.
Thanks in advance

 

[GeneralDisorder]

You installed an older CTIS controller with power on the J1939 pins and have smoked the J1939 termination resistors. The older modules can only be used on A0 trucks or other older applications. They only use the J1708 bus and the pins for the J1939 were, at that time, undocumented and just happen to have power on the pins later used for the low voltage J1939 high and low circuits.

Your original controller is likely fine. The blinking indicates a fault and no controller is going to work on that truck till you correct the fault. Usually it's from trucks sitting and the tires drifting too far apart for the controller to cope with. Air all your tires up to the SAME pressure and try the original controller again after you replace the burnt out termination resistors. One is under the PDP and is sometimes hiding so look VERY thoroughly. The other is next to the ECM in the engine bay.

For lasting results you probably need to at least rebuild the wheel valves, rebuild the PCU, and find/fix all leaks in the system. Also check for any plugged vents for the PCU under the passenger side of the dash, and any tires that aren't holding need to be fixed. The system treats all the tires AS IF THEY WERE A SINGLE TIRE so a leak at any tire is a leak that will confuse and potentially fault out the CTIS controller.

You should get a laptop with a J1939 interface and download the free Dana software to talk to the controller and find out exactly what it's on about - after you fix the coms resistors of course. Can't communicate without the termination resistors.

 

[Keith Knight]

He is spot on, sounds like a lot to do but well worth the time and effort. Having a proper working CTIS is great and underrated.

 

[Ronmar]

Yep, your ABS light is because the data bus end resistor is fried And it cannot communicate properly… If I recall there is more than one in the system, but I forget their locations.

back to your original problem what exactly was flashing on your first controller? Specific LED’s or all 5? I agree you original controller is probably OK. Basically the CTIS controller is controlling the tire pressure in these very large air bombs we roll around on, using a single combined pressure sensor and a stopwatch… it is expecting certain things to happen in a certain time frame and it WILL fault at the drop of a hat… Most all fault conditions are due to leakage and failure to meet a expected goal. If it doesn’t do anything,(doesnt try to test pressure) it could be the wet tank pressure switch, and eventually it times out because the tank never gets above 117PSI. Do your air gauges get to 125, as that is where the governor should put them. If it faults immediately after the wet tank reaches pressure(125 on the pri/sec gauges dryer vents) after startup. it may have failed its atmospheric pressure test. If it closes the control solenoid, pressurizes the system and tries to test tire pressure and faults, you may have a leaking/low tire and since the sensor does not see a stable pressure as the fuller tires send air to the low tire, it will fault… other types of faults could be during a fill where it is expecting gains in pressure at each check but a leak prevents it from seeing what it expects to see after a certain amount of fill time…

best way to look for leaks is to apply shop air and with the ign on/engine off, jumper the control solenoid to seal the system and briefly jumper the supply solenoid to give it a shot of air to pressurize and open the wheel valves. Then while it is setting with all the system pressurized go look for leaks. Start at the dump valves right side of the transmission and over rear axles. Any air coming out of the dump valve vent ports indicates a leak somewhere in the system and the dump valves are venting tire air to try and match the decreasing system pressure caused by the leak…

you should want to put together a diagnostic laptop and comms adapter/interface… You will need it eventually to talk to engine, trans, ABS or CTIS…