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Disconnect the line at the PCU i mentioned earlier that feeds down to the dump valves and wheel valves, and using a blowgun on that line, give it a brief shot of 60 PSI air. That shot of air should open the wheel valves and all the tires should equalize at the same pressure. As long as you...

he said they are dumping to 10PSI... it must be mostly blocked, as the system must build enough pressure to open the wheel valves in the first place... so air is coming from some place(leaking wheel valve, leaking PCU supply solenoid). a system open to atmosphere would have trouble building...

Quick fix, on the back side of the pressure control unit under the passenger dash on the port labeled C I think, disconnect the line to the wheels. The other line is the pressure input from the wet tank. The pressure line typicallt has a T right where it comes thru the floor as that air also...

woops, missed the 1078 2000 model. cat 3126 should have an ex brake butterfly assembly connected to the turbocharger output...

What year and model truck are we talking about? On the LMTV, Not retarder, exhaust brake... The retarder is a hydraulic brake system built into Allison 3000/4000 series transmissions as an option. The MD3070 AWD trans we use is incapable of it as the transfer case occupies the space on the...

The tire lift cranes sometime get stuck in the up position, are you referring to that?

Wow, an actual bad relay! Cool, that doesn’t happen very often:)

in the drawing I attached that same 12v should also be on k10 pin 87 and is what feeds thru the relay to pin 30 when k10 energizes, to light the brake lights. it may be you have a bad connection somewhere along the source path from K6. it delivers measurable voltage unloaded and enough current...

K-30 and 31 are for feeding 24v commercial trailer lights via the 10 pin rear connector. You can remove them if you wish… pull K10 and connect a meter from pin 86 to 85(ground). You should see 12v there when you step on the pedal… You can bypass the light switch by jumping pin K to C which...

K6 is a good sign, means the switches are OK. from K6 it passes thru the light switch and activates K10. K10 switches the light output from flasher to brakes. Flashers working means K10’s de-energized contacts(30-87A) and all the rest of the light circuit is also OK. So I suspect you have...

What truck do you have? The brake circuit is different between the A0 and A1…

mine is already separated and that upper frame rail(now my floor assembly) is still light enough to be lifted… Have you sourced that part?

Could have been the PTO gears wearing in…

You should see something on the tcase drainplug if it is that C6 thrust bearing. Allison wants a small fortune for that composite washer:O

Well its connected to the TCU because thats where the speed signal comes from(output speed sensor down in the transfer case). The signal also feeds the CTIS controller that counts pulses to trigger its overspeed response. Since you have more than halved the pulses from the trans at any given...

In the end its a cat tune, so it is as probably as safe and reliable as any other cat product run at that level of output:) How hard you run things ultimately comes down to you...

Once the pump is pushing fluid, it does not take all that many pumps to make anything move if things are working right. again, this could be as simple as the hoses are connected backwards on one of the pumps… that is a good idea to confirm pump operation, connect a cylinder directly to the...

If the hand pump pumps fluid out its pressure port, it shouldn’t take all that long to prime/fill lines and start building pressure/doing work. The hand pump is sealed/has no vent port. As the hand pump pushes out fluid, it pulls a vacuum in the reservoir and should draw fluid in from the AOP...

Yea its got about a 4’ dipstick:)

step 1 establish you have a source or pressurized oil. Even if the AOP is shot, and they often are, the hand pump should work, they are pretty robust units, but also easy to test. Remove the line from the lower port on the hand pump(pretty sure that is the output) cap/block its output and see...