RV Holding Tank Sensor Wiring Diagram (How To Wire – Guide)

When it comes to wiring, you just connect two points and forget about it. However, what makes wiring difficult is the location of those two points and the route of the wire. That is not easy to deal with at times.

When your holding tank monitors malfunction, it could be because a wire has broken loose, become frayed, or simply broke. Wiring is easy as all you usually have to do is remove the old wire and connect a new one. It just takes time to make the right connection.

To learn more about this topic, just continue to read our article. It has the information you need to handle this situation when it happens to you. Take a few minutes to see how this important information helps you out with a difficult issue.

Holding Tanks Make Mistakes


It is not a perfect system and the holding tank sensors can be one of the most frustrating aspects of RV life. When they go bad or something is blocking the sensor, you do not get an accurate read. That keeps you guessing and wondering if you need to dump or not.

There are several reasons why holding tanks make mistakes and you are probably well aware of at least two of them. Something is blocking the sensor or the sensor has gone bad.

It is not always easy to tell when a sensor goes bad and you would need inaccurate readings after several cleaning attempts to realize that is the problem. But there is a third major way that sends your holding tank monitor an inaccurate reading.

The wires have broken, become frayed or there is a loose or no connection. Rewiring is easy if the problem is just one wire. But when you have to deal with several wires then you need to know more about wiring and which color goes where.

The upcoming wiring diagram should help you with that problem. Holding tanks are not wired as you may expect and some owners have been surprised by finding only 5 wires connecting all holding tanks to the same monitor. They thought there would be at least 15 wires.

While this simplifies the problem, you still have to make the right connections and do proper routing to get the sensors working again.

How To Wire RV Tank Sensors


This can be tricky as the sensors are wired a little differently between models. For example, if your holding tank monitors thirds, then the wire harness will only have 3 wires attached to the harness. If it monitors quarters then you will have 4 wires to deal with.

The good news is that all wires are attached to a central red signal connection. That has 4 wires or 3, leading into it and one or two leading to your panel. When a sensor is bad, you have to replace the whole harness at that point.

First, you remove the old harness. Then replace it with the new one. The third step is to make sure you have the harness in the right position as colors matter. On e the three wire harness the yellow goes to 1/3 full; the green wire goes to 2/3 full; and the orange wire to the full sensor.

Just attach the wires in that order. For a 4 wire harness, the order should be yellow, green, orange, and red. You know how to attach wires. Just make sure the connections are tight.

Be careful as the signal wire is usually red. It is the sole wire going from the harness to the monitor. A white ground wire may be placed somewhere on the holding tank but it is not attached to the harness.

Holding Tank Sensor Wiring Tips


There are not many tips for this project simply because the wiring is wiring. There is only one way to do it and the only tips you would need would be for routing. And that option may be done for you because of the design of the RV.

The best tip we can give is to make sure your connections are done right, they are tight and not in any danger of being hit by anything that comes underneath your RV.

Make sure to have a little slack in the wiring so that bumps and jolts do not damage the wires. The wires should be easy to attach to the sensors as they come with looped connectors that are crimped into place on the wires.

Keep in mind that RVs are wired differently so look to see if there is a better way to route those wires when you are underneath your RV or trailer.

RV Holding Tank Sensor Wiring Diagram

RV-Holding-Tank-Sensor-Wiring-Diagram (2)

We are going to link you to a couple of websites that have wire diagrams. The reason for this is that they both have multiple diagrams you may find useful as you work on your holding tanks.

They also have some good instructions to help you do this project easily. The first website is here and the second one is here. Also, if you want to read what KIB has to say, click here. Then scroll down to post #6 to read their letter to one owner. It is too detailed and long to place here for you.

Those diagrams should help you but if not, a good internet search should get you other options for you to use.

Some Final Words

Wiring is easy it is the positioning and location of the wires and their connections that make it hard. Sometimes you have to lower the holding tanks to access the harness and that can get expensive.

Take your time as this is not a very time-consuming task. The set up is not that complicated either as you will have the old harness to guide your work. Just make sure you study the wires before removing them.

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