[cfree3]

Does the tag bag on the driver side inflate when the coach is in travel mode? You said it does not in level mode. Just wanting to confirm.

One, you can start and run the engine without the alternator. Make sure all positive cables you have disconnected are insulated and not touching ground. Merge the battery banks. The engine will run just fine. If you are only producing 90 psi with the 120 compressor, then it may not be enough pressure to raise the left rear with the slide out. The slides being out require a lot more pressure on the left side because of the leverage of the weight. Also it does not take nearly as much pressure in the front bags as the rear to raise the coach.

Two, the reason you may be seeing different behaviors between travel and raise mode is something that HWH/Newell does with 120V pump wiring. Normally, the pump is wired through a common well pump switch that is usually set to come on at 70 psi and turn off at 90 psi. So if you are in travel mode without the engine compressor running the max pressure you will see is 90 psi. I don't think that is enough to raise the driver rear with the slide out. HOWEVER, if you put the HWH control panel in Level, and you press any button to raise the coach or it goes into Autolevel, the HWH panel activates a relay by the 120V pump that bypasses the pressure switch. It will produce up 150 psi of pressure in that mode. I know, I proved it by exploding an air bag. So, in manual you may indeed have more pressure to work with.

Will you confirm that the tag axle switch on the dash is in the middle position?

The travel solenoids may be stuck closed. There are two ways I can think off to check this. The first is mark the connectors, then unscrew the right and left solenoid assemblies from the manifold and swap them. Be aware that any air pressure in the rear bags will escape when doing this so let the coach completely down before unscrewing them from the manifold. If the problem follows the solenoid then the problem is identified.

The second way is to let the coach down. Unscrew the two airlines on the back of the manifold. Unscrew the one closest to the bulkhead first. Turn the air compressor back on. If the HCV is working then air should come out of the line you just unscrewed. If you have air at that line, then screw it back on the manifold. Unscrew the other line, the one going to the air bag tank. Air should now come out of the fitting on the manifold if the coach is in travel mode and ignition on. If it doesn't then you have a stuck solenoid valve.

As far as the two solenoid valves on the tag. Yes it is possible that something is going on there, but I would definitely eliminate the other possibilities first. Here is why. Both of those solenoids are three way. In there unactivated mode, the switch in the middle position, they are set to pass air straight through. If the reduce pressure mode is activated, then the reduce three way is changed to the alternate position which blocks the path from the drive bag air tank and opens the tag bag tank to exhaust to atmosphere. If this were the case you should be able to hear air escaping from the solenoid. If the increase pressure solenoid were stuck in the alternate position, the tag bag would inflate to the pressure supplied by the compressor.

There are a few more things to try or consider.

Is is possible that the tag bag was plumbed incorrectly when it was replaced. This history of the rear dragging is concerning.

I would also chock the coach from pancaking me, and do the following. Crawl between the drive tire and the tag tire facing the drive tire. Take a little grease or gojo and lube the knob that the lower part of the vertical HCV attaches to. You want to slide the arm off of the axle mount. With the coach in travel mode and ignition on. move the vertical arm up about 1.5 inches. That should cause air to flow into the air bags. To continue the test, move the arm down about an inch below the mount. You should immediately hear air exhausting from the HCV. I don't mean to be cavalier about being under the coach and messing with the air bags, but if you are between the tires, the coach can't sit on you.

Hope this helps, and thank you for establishing a baseline.

The answer to the question is that the left tag bag does not inflate in either travel or lift mode. The left drive bags are lifting totally on lift mode but not travel mode. My question at this point is at the 6 pack, the air line going into the travel solenoid is supplied by the air coming from the HCV...correct? Then how does it leave the 6 pack?? Does it go out the lift solenoids to the supply tanks? It would help if there were directional arrows on the direction of air flow through the schematic in the various modes. Thanks.