CTIS 5 flashing lights, no air leaks, no mechanical faults.

[Coffey1]

Mine will dump air when tires get hot and build pressure past set point.
It don't stay on long.

 

[Hawkdriver]

Coffey1 thanks sir I will check that.

 

[Coffey1]

Your very welcome sir.

 

[Hawkdriver]

Okay I have read all the threads and done some testing on my CTIS and this is where I am at. When pressure reaches 120 I hear noise from the pcu air dumps out of the front and rear exhaust valves and then the infamous 5 flashing lights. I can hear a small amount of air always exhausting from the lower threaded hole on the bottom of the pcu. Not sure if that's normal.

I have checked all solenoids and they all read .45 or higher. Took the pcu apart cleaned it and put it back together. All tires seem to hold air and all schrader valves have been removed from wheels. I'm at the end of my ideas. Only things that are left are the transducer or that leaking air from the bottom of the pcu

Any ideas?

Dan

 

[Alexsha]

Leaking air is always the best bet. If the system detected a leak it will go to 5 lights.

 

[crcarson26]

I am having a very similar 5 flashing lights on my 1998 M1088. Read through parts of the manual up to where it asks to verify leaking lines. I found a significant leak at the Pressure Protection Valve on the wet tank. I have attached a pic below. Does anyone know where I can find one of these? Can it be replaced with a newer model rather than the original NOS part? Looks to be just a simple adjustable pressure regulating valve. Any thoughts or suggestions are welcome!!

 

[tennmogger]

I have two that leak. With the screws at the ends, the cover warps and loses the seal and air leaks out. I cut a thin gasket and installed gasket with sealer. It's a very simple over-pressure valve but watch out for the big spring when you take out the screws. You don't even have to take the assembly off to work on it. Just clean out the housing and gasket the top cover when you reassemble.

Don't know a source but did find out by accident that this is the same over-pressure valve used on a 406 Unimog!

An over-pressure valve holds back air until a pre-determined (set with the bolt) pressure is reached in the primary circuits, then opens and provides air beyond, to other less vital circuits.

 

[Keith Knight]

Re open this old thread. I’m in a M1078A1 2003, my CTIS has been working without any issues all tires holding air. In the last 7 months I’ve driven over 10,000 miles and this morning I turned the CTIS on and highway light blinks like normal then I can here the valve in the dash start to do its normal thing but then the sounds stop and the 5 lights start flashing. Because I can hear it attempt to check pressure makes me think it’s an air leak. So would a small leak on this over pressure protection valve cause all 5 lights to flash.

 

[Keith Knight]