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Topic: HWH Aux Pump does not come on. (Read 597 times) previous topic - next topic

HWH Aux Pump does not come on.

1994 U280.

The HWH leveling system works fine with engine running. With engine off, control panel works but the aux pump will not come on to raise the coach. Dumping works fine. I found 2 fuses labeled HWH under the dash, both are good. This has all the aspects of a blown fuse to the pump. When I push an up arrow on the panel I can hear some solenoid action but no pump.

Anyone know of another fuse location? Manual says a 20A inline fuse at the pump but I can't find it. Or maybe it is a problem other than a fuse?
1994 U280, Build 4490
Deming, NM.

Re: HWH Aux Pump does not come on.

Reply #1 –
Do not know your system, but if the pressure switch fails, it could be the reason the compressor does not run, would look there first, then start with a VOM, and see where the Voltage went or stops.

Re: HWH Aux Pump does not come on.

Reply #2 –
Quote from: Twig –
1994 U280.  Anyone know of another fuse location?

Do you have the wiring diagrams for your coach?

If so, look on the one titled "U280-U300 Automotive Wiring Diagram" (B-2126).  On the top right side of the page, there are 3 big round devices marked "90A".  Directly below them are 7 circuit breakers, in two rows.  One of these circuit breakers (second from the top in the right-hand row) is for the "HWH COMP".  They are resettable...if it is "tripped" there will be a little plastic button sticking out the side.  Push this in to reset the circuit breaker.

On my coach, this panel is located in the large center cargo bay, on the wall right next to the charger-converter.  Covered with a sheet of white fiberglass.  Lots of heavy electrical cables going under it.  Use caution when working in this area - some of the connections may be "ALWAYS HOT".
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Surely, no age has been more fraught with insecurity than our own present time."

Re: HWH Aux Pump does not come on.

Reply #3 –
The circuit breakers behind the fiberglass cover are all good. The pressure switch is clicking so it must be ok. When I put 12V to the connecter that the orange wire hooks to on the pressure switch, the pump will come on and level the coach. However, I have to remove the 12V jumper to get the pump to stop.

Interestingly, the BROWN wire hooked to the pressure switch goes through a connector and the schematic says it goes to the 12V signal at the control box. But it doesn't and never has. It has been cut and the harness removed for some reason. It has always run like this without trouble.

So.......now the troubleshooting has me at the point where I cannot find WHERE the 12V comes from to tell the compressor to come on. On one post of the solenoid is a constant 12V fed by a blue wire. I see no other wires coming from anywhere except the ground.
1994 U280, Build 4490
Deming, NM.

Re: HWH Aux Pump does not come on.

Reply #4 –
I have an inline fuse very near the compressor in my 2002.  I used to remove it before I installed a switch.  It wasn't very hidden, tho.
The selected media item is not currently available.Brad & Christine Slaughter
Was:  1990 U280 36'
Was:  2002 U270 36' (With a bathroom door) Build #5981
Is:  2021 Leisure Travel Van Wonder 24RL
2015 Jeep JKU, 2003 S10 QC 4x4 or 2017 C-Max
Lake Havasu City, AZ (or Gillette, WY)

Re: HWH Aux Pump does not come on.

Reply #5 –
No inline fuses. The main thing here is not locating a control signal from anywhere. I can run the pump by applying 12v to the pressure switch but cannot for the life of me figure out how it gets there automatically. Motor won't turn on in either automatic or manual operation of the control panel. Otherwise, everything is normal.
1994 U280, Build 4490
Deming, NM.

Re: HWH Aux Pump does not come on.

Reply #6 –
Do you have the HWH Repair Manual for your system?  If not, they are located here:

HWH Service Manuals

My coach uses the 600 Series (ML11148) - marked "Foretravel Motor Homes".  Under "Repair Steps", see Part 4, Sec. E, "The compressor will not run when pushing up arrow".

If you have already read this manual, then disregard.
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Surely, no age has been more fraught with insecurity than our own present time."