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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...

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)...

I have heard of people finding those. Would kind of tend to interfere with the deflate cycle on that tire I think:)

Or it just has some crap in it allowing tire air to leak past...

Hadnt helped anyone with this issue either. Hope it works

No that sounds about right. Should be just a loud honkish whoosh. The more you push on that relief, the higher the pressure in the manifold should be, which would lessen/slow the dump whoosh because the pressure would be closer to the tire pressure... as the dump port closes, it can make some...

well you could unscrew the pressure sensor, connect a low pressure gauge and manually run a deflate with jumpers and see what pressure the relief holds the system at like I do on my manual system to monitor tire pressure…

Mine runs about 7PSI when deflating. 5.5 seems a bit low and closing in on the point where the wheel valves close… If you held a little pressure on that relief with your fingertip, you should see an increase in that deflate pressure…

I dont think the troubleshooting guide goes as far into it as you have. They the assumw the controller is ok, so they say If 5v from controller is ok, replace the sensor. Was recently helping someone with a failure and worked our way to the pressure sender also...

Well a 24p manual might show you if there is a difference in part numbers on the PCU components between the different trucks. I would not think there would be though, as the relief pressure really needs to be that low(just above the pressure that opens the wheel valves) to deliver the fastest...

I believe they are absolute so at .05v per PSI, 14.something psi atmospheric pressure should yield .7 something volt return. Dont forget garbage in=garbage out. Those voltages above assume a proper 5.00v input. A different input would yield a different response per pound when divided by 100...

You should be able to probe the sensor wires to see ground, 5v from the controller and whatever the return voltage the controller is seeing coming out of the sensor. Of course it needs a good wiring path between controller and sensor…

Ok, that was one of my other questions, does it fill to the correct pressure. It uses a 0-5v 0-100PSI sensor. It has 3 wires. It gets ground and 5VDC from the controller and it returns 0-5v to the controller based on the pressure it sees. when you were working on the PCU did you remove the...

That doesn’t sound like a very aggressive deflate. it looked like it ran a full deflate cycle then faulted as it checked pressure. If that relief were partly plugged, it would not vent the manifold down to that low 6-7 PSI. The dump valves dump based on pressure differential, if the relief...

The brass relief would be the place I would look. When it starts a deflate cycle you should get an initial woosh out of the relief as it vents pressure down to its set pressure(~6.5psi). It will then vent air slow and steady as it purges the air being fed back from the dump valves to maintain...