Oasis Zone 2 Fault - fuse good, no power to pump

[MCRV Passion]

Baffled here, I confirmed fuse ok, "assumed" pump bad so replaced and now I diagnose to find no power at pump terminals yet though fuse good. The fuse terminals appear very solid.

Spoke with tech assist at ITR and no assist beyond likely fuse terminals must be loose. But they look and feel solid. Hate the thought of pulling control board and replacing it.

Anyone have the wiring diagram showing fuse to pump logic (or) know what is between the fuse and power to pump??

Thinking they have a relay or what could it be preventing power to pump??.

I have looked at all the great resources in Oasis links and the internal wiring diagram but not seeing anything about fuse>pump wiring

[ptw]

Are you getting a green light on the zone board for the Heat Loop Pump? The power goes from the relay to the fuse then the pump. Red indicates blown fuse but only when the power is on to the pump.

[MCRV Passion]

My “zone fault” = red lights come on when call for heat in Z2 furnace mode at coach display and control board.

[Mr. T]

When I had my summer loop pump replaced, the technician verified the pump was bad by connecting wires from a battery (off what looked like a cordless drill) to the pump.
After watching what it takes to replace them, I'll be doing it myself if it happens again.

[ptw]

Originally Posted by MCRV Passion

My “zone fault” = red lights come on when call for heat in Z2 furnace mode at coach display and control board.

The red light is a blown fuse indicator. The fuse is in the panel that I pictured in my previous post. The red light is wired across the fuse terminals. The light comes on when the pump relay is closed and there is an open across the fuse.

If you look close in the pictures I previously posted, the bottom left fuse is pulled for the summer loop pump and the red light is illuminated.

[MCRV Passion]

Thanks, if that’s the case then it seems I’ll have to pull the control board and see why/how the fuse terminals can be open when a good fuse is in there.

Continuity confirmed thru fuse and even switched fuse 1,2 and still Z2 goes red.

Hate to pull board as such very tight fit dang it. Z2 on my rig is just bathroom so may just do without until I get back to home base in April.

[alank]

I'm speaking from Aqua Hot knowledge here, but the units are similar. In the Aqua Hot, the pumps are turned ON and OFF by a switch in the ground wire, not the 12V wire. You say the fuse is good, so measure the motor wire voltage, at the motor, to a ground terminal on the OASIS, not the ground wire on the motor. See if the motor terminal has 12V. If it does, connect the motor ground terminal to an OASIS ground terminal (bypassing a ground switch) to see if the motor runs. If it runs, look back up the ground wire to see where the ground connection isn't being made.

If the other motor is running, you could connect a jumper from the running motor ground wire to the non-running motor ground wire, to see if it runs. That would also indicate the ground wire isn't getting connection somewhere.

[MCRV Passion]

I’ve checked voltage at motor terminal + to chassis ground and 0. I plugged new pump into Z1 terminals and it works.

No voltage is getting to the motor, seems due to fuse not passing it. Sure wish they provided schematic on fuse/relay/ thermostat so I understood the path.

[BonS]

Originally Posted by alank

I'm speaking from Aqua Hot knowledge here, but the units are similar. In the Aqua Hot, the pumps are turned ON and OFF by a switch in the ground wire, not the 12V wire.

The Aqua Hot is low side switched but the Oasis is high side switched.

[flyboy013]

Inside the Oasis distribution box where the clear PEX lines enter/exit there is a temperature sensor attached to the water line. This temperature sensor is in line such that the power to the summer pump passes through it. The pump only gets power (ie turns on) when the water is not warm enough. This could explain why you have power at the fuse and not the pump itself.

I would recommend tracing the wires connected to the summer loop pump. One of them goes to this temperature sensor. Check for voltage on the other side of this sensor. And/Or disconnect and check switch continuity. If you have power on the other side of the sensor (or no continuity), you may be able to temporary bypass it to verify that all is good with the rest of the system.

Here is a picture that ITR had provided me a few months ago with I was troubleshooting an summer pump related issue.

[MCRV Passion]

Thanks for detail but unless I misunderstand your reply my issue is with #2 zone heating pump. Zone 1 & DHW zone works ok. Summer stat would not be part of the current path that I can see.

[flyboy013]

Sorry for the last post. I drafted it offline and posted it to the wrong thread.

I do have some suggestions for troubleshooting.

The oasis board has circuitry to determine if the fuse is blown. Since you have verified that the fuse is good, then there must be an issue with the board itself. Depending on your skill level, this is something you may be able to troubleshoot and repair yourself.

While we don’t have the schematic for the circuit board, it was stated that the power flows into the relay, then through the fuse and then out the board through one of the connectors to the pump.

You stated that power “though fuse [was] good“ and that the fuse terminal was also solid so you may have already done this first check that I am suggesting. The top of the each fuse has a test point that you can touch with a test light or multimeter probe. I would suggest checking to see if there is any voltage on either side of the fuse. If not then perhaps the relay is bad. I would attempt to use the probe on the relay leads to determine if there is voltage entering and exiting the relay. My thought is that the relay may have gone bad or solder connecting the relay or fuse connector to the board may be bad. While it’s unlikely, it does happen and your issue definitely sounds like a problem with the board given that the red LED is on and you have confirmed that the fuse it good.

I would also do a continuity test from the pump’s 12V wire back to the board. I would test between the pump to the fuse terminal. If that fails you can repeat the test testing various intermediate points (ie connectors). While we don’t have a wiring diagram you should be able to disconnect the 9 or 12 pin connector feeding the distribution module and do a continuity test to determine which pin on the connector is for the zone 2 pump. From there you have the wire color in the harness from that connector back to the oasis circuit board. You could do another continuity test from the intermediate connector to the connector at the board. And then from that connector to the fuse terminal.

I think best case scenario is that you have a loose or broken wire somewhere between the board and the pump (although that doesn’t explain the red LED). Worse case there is an issue with the board which would require a little bit of solder or perhaps the replacement of a relay.

Again I think the first order of business would be to test the voltage at the fuse test points to verify if the problem is before or after the fuse.

[MCRV Passion]

Great advise, I confirmed fuse terminal voltage in and also that pump wire lead from board to pump all ok.

I don’t want to tackle repair of control board so I’ll have to seek price on new control board I think at this point.


I’ll pull it out when I’m home to see if it’s just fuse terminal at back of board, if not that new board it’ll be now.

[Sugaree]

Originally Posted by Mr. T

When I had my summer loop pump replaced, the technician verified the pump was bad by connecting wires from a battery (off what looked like a cordless drill) to the pump.
After watching what it takes to replace them, I'll be doing it myself if it happens again.

Trust me…it will fail again. We have already been through 2 pumps over the past year. Definitely order replacement pumps through ITR as RV dealers are marking them up significantly.