Grey Waste Tank Sensor Wiring

Hello everyone,

I need help figuring out a wiring problem I'm having with my grey tank sensors wiring, (it's a problem that I created!!).

I replaced my grey tank sensors with Horst Miracle Probes, which was a little more work than I anticipated because I had to drill new 3/8 in. holes on the other side of the tank due to having no clearance at all between the tank and the trailer frame to remove the wiring and to remove the old sensors.

Anyway, after installing the new sensors in the newly drill holes, I used new wires to connect to the existing wires, which I should have just stripped and joined together and be done!! Instead I decided to remove a jacket that joined all 4 sensor wires together to investigate and see what was in there. Bad choice I made taking that jacket off!! because was in there are the 4 sensor wires and 3 small resistors.

I thought, ok let me put it back together and use electrical tape to insulate each wire/resistor separately just in case they are not suppose to be contacting each other; I should have taken some pictures right there and then!!, because as soon as I started taping them they came apart/detached from wherever they were soldered or attached!!

Now I have no idea where the end of the 2 resistors shown in the photo go to.

Does anyone know why there are resistors in the sensor wiring? Maybe to reduce voltage? If so to what?

Were they soldered somehow in a daisy chain?

The Light Gray wire with the connector screw cap connects all 4 wires and then goes up thru the floor to the inside of trailer.

A while back another forum member had a tank sensor wiring question due to a broken wire at that Same/Similar attaching point.
Here is the link:

https://www.hilotrailerforum.com/f27...or-wires-5165/

Forum member Treeclimber suggested to him to "strip them back, twist them together and solder".

I supposed that would eliminate that plastic junction, although I think there may be some type of resistors in there also like in mine.

Would that be safe to do (join them together, no resistor)?

Would eliminating the resistors burn/short something out? What purpose are they serving?

I have attached some photos that may give you a better idea of what I'm talking about.

Thank you for any help with this and sorry for the long post.

Angel - I just looked online for a sensor installation video and found this one: There's some others too. In this one, he talks about a "wiring harness" you should probably get that will replace the one in your trailer. It has that funny looking little connector that's in the wiring that Treeclimber replied to. So, I suspect if you just get the harness, you can attach it to your sensors and then connect the other ends to the trailer wiring.

- Jack

Here's another video that has the same kind of wiring harness. I'm of the opinion that you don't really need those resistors, and I don't know what they're for. I doubt seriously that you'll burn anything out without them. Possibly, your sensor panel inside the trailer needs this voltage reduction, and if so, you may have to replace that panel too.

- Jack

qucik check on what the resiusters are used fir
Electrical resistors are passive components that provide electrical resistance to current flow12345. Here are some key points:
Definition: A resistor is a two-terminal element that limits and regulates current flow in electrical and electronic circuits.
Measurement Unit: Resistance is measured in Ohms (Ω).
Function: Resistors are used for various purposes, including limiting current, dividing voltage, and generating heat.

We just got back from a six day camping trip, and I'm happy to report that after drilling new holes on the grey waste tank to install the new Horst Miracle Probes Tank Sensors, there are no leaks and the panel is registering each tank level sensor correctly!! It always showed either 1/2 or 3/4 full even when empty (thank goodness, just a little piece of mind knowing tank level).

Thank you Jack for pointing me to that YouTube video of the tank sensor wiring harness.
And thanks to everyone for your suggestions.

As I mentioned on this post Hilo installed resistors on the wiring harness to the tank sensors (which I accidentally broke when taking things apart, oops). I figured it out, the resistors are Daisy Chained together from one sensor wire to the next with different Ohm values.

The new wiring harness that Jack suggested and that I ordered Does Have Resistors built in (I guess to protect the panel inside). The only issue I ran into was that my Hilo has four sensors 1/4 full, 1/2 full, 3/4 full and Full and the grounding sensor probe wire. The new wiring harness only has three wire connectors for 1/3 full, 2/3 full and Full, plus the grounding probe wire...yikes!!

I measured the ohm resistance on the originals and ordered some with similar values, I then daisy chained that 4th sensor probe to the sensor probe next to it. Everything seems to be working really well!! Yay!!

Great work Angel! It's amazing what one can do with a little thought. Glad you got them working - I've been happy with the Miracle Probes in my trailer since I installed them.

- Jack