CTIS...soo close to working properly

[aw113sgte]

How does the Spicer PCU control the steers vs the rears? Multiposition solenoid? I can get the fronts to dump with pressurizing the deflate line with air, but not the rears.

They are all connected, I wouldn't be surprised if you have some valve stem cores in your rear wheels.

 

[Reworked LMTV]

They are all connected, I wouldn't be surprised if you have some valve stem cores in your rear wheels?

No valve stems. Mine is a 6x6. How does the PCU sample air pressures on the front and rear wheels

 

[GeneralDisorder]

No valve stems. Mine is a 6x6. How does the PCU sample air pressures on the front and rear wheels

What he was referring to is someone putting Shrader cores into the wheel valve stems on the back wheels. Normally the Shrader core is in the CTIS wheel valve but can also be installed into the tire valve stem. Doing so will prevent them from deflating (will still inflate).

 

[Reworked LMTV]

What he was referring to is someone putting Shrader cores into the wheel valve stems on the back wheels. Normally the Shrader core is in the CTIS wheel valve but can also be installed into the tire valve stem. Doing so will prevent them from deflating (will still inflate).

Yes, I did find one in a front tire.

 

[Ronmar]

How does the Spicer PCU control the steers vs the rears? Multiposition solenoid? I can get the fronts to dump with pressurizing the deflate line with air, but not the rears.

All the axles are plumbed together. There is a dump valve for each axle that connects to each hub/wheel.

The line out of the PCU runs down to a T connection right behind the transmission on the passenger side. One leg of the T runs forward to the front axle dump valve(right side of trans).. there are 2 lines out of it to left and right front hubs.

The other leg of the T goes to the rear dump valve located on the rear side of the crossmember over the rear axle on a 4X4.

On a 6X there is another T back there that goes to the 2nd dump for the 2nd axle.

If one axle is not dumping with less than current tire pressure applied to the line from the PCU, but greater than 5PSI(to keep wheel valves open), you may have a clogged line, bad/stuck dump valve or bad wheel valves or connections to the tires...

 

[Reworked LMTV]

All the axles are plumbed together. There is a dump valve for each axle that connects to each hub/wheel.

The line out of the PCU runs down to a T connection right behind the transmission on the passenger side. One leg of the T runs forward to the front axle dump valve(right side of trans).. there are 2 lines out of it to left and right front hubs.

The other leg of the T goes to the rear dump valve located on the rear side of the crossmember over the rear axle on a 4X4.

On a 6X there is another T back there that goes to the 2nd dump for the 2nd axle.

If one axle is not dumping with less than current tire pressure applied to the line from the PCU, but greater than 5PSI(to keep wheel valves open), you may have a clogged line, bad/stuck dump valve or bad wheel valves or connections to the tires...

Thank you. Dump valves are new. Thinking a line too.

 

[Ronmar]

Like I mentioned above, you must feed them enough air to hold the wheel valves open, but less than the current tire pressure to get them to dump. A good way to do this is disconnect the output line from the PCU and connect an air pressure regulator and a source of compressed air. Whatever you set that regulator to, the tires should match, either by adding air from the regulator or dumping air out of the dump valves to get down to the pressure being applied by the regulator. This is a great setup to hold the system at pressure and look for leaks…

 

[Reworked LMTV]

Like I mentioned above, you must feed them enough air to hold the wheel valves open, but less than the current tire pressure to get them to dump. A good way to do this is disconnect the output line from the PCU and connect an air pressure regulator and a source of compressed air. Whatever you set that regulator to, the tires should match, either by adding air from the regulator or dumping air out of the dump valves to get down to the pressure being applied by theto tj regulator. This is a great setup to hold the system at pressure and look for leaks…

Found lose fittings at dump valves and at the diaphragm manifolds at the wheels. Used a small bore pipe cleaner from Amazon to check the hoses and fittings all the way to the hub. No blockages.