Garnet SeeLeveL II 709-N2K NLP

Questions and Answers

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Rachel Sanchez DVMAug 20, 2025
Why is there a signal power problem with my Garnet SeeLeveL II 709-N2K NLP?
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  Brian HallAug 20, 2025
  A signal power problem with Garnet Tank Equipment may be due to several factors, including a sender detached from the tank, excessive buildup inside the tank, faulty wiring to the sender, low battery voltage, or a defective sender. Typical signal power should be between 50% and 60%, with a minimum of 20% required for proper operation. P00 represents 100%.
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Erica WebbAug 22, 2025
What to do if my Garnet SeeLeveL II 709-N2K NLP displays an Error?
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  lindarichAug 22, 2025
  If you see an 'Error' message on your Garnet Tank Equipment display, it indicates signal corruption between the sender and the display. This can be caused by bad wiring, faulty senders, or multiple senders programmed with the same settings. To resolve this, check that all senders are programmed correctly. If the programming is correct, try replacing the sender that is causing the error.
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Paul GonzalezAug 25, 2025
What to do if Garnet SeeLeveL II 709-N2K NLP readings jump or are inaccurate?
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  Terry NunezAug 25, 2025
  If your Garnet Tank Equipment readings are jumping or inaccurate, it could be due to 120VAC interference causing stalls and gaps in the readings, or resistance between multiple ground circuits in your RV. Always ground the senders and the console to the same ground circuit to resolve this issue.
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Sara BrownAug 26, 2025
What to do if dual Garnet SeeLeveL II 709-N2K NLP displays don't read the same?
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  aaron32Aug 26, 2025
  If you have a dual console system and the two Garnet Tank Equipment displays show different readings, the most likely cause is a bad console ground. Ensure that both console grounds and the sender grounds are connected together using ground wiring.
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Connor McknightAug 28, 2025
How to avoid damaging Garnet Tank Equipment display due to excessive current?
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  rachelbradshawAug 28, 2025
  To prevent damage to the display or pump switch of your Garnet Tank Equipment due to excessive current, especially with large pumps that can draw over 10 amps, you must use a relay. This will prevent the display console's printed circuit from overheating and causing permanent damage.
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Robert LynchAug 30, 2025
What to do if my Garnet SeeLeveL II 709-N2K NLP freezes?
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  mendozarobertAug 30, 2025
  If your Garnet Tank Equipment system freezes or becomes unresponsive, try rebooting it. Shut off the 12V power to the system for a few seconds, then turn it back on.
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Heather FordSep 1, 2025
What to do if Garnet SeeLeveL II 709-N2K NLP Tank Equipment shows water level after draining?
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  Kenneth JonesSep 1, 2025
  If your Garnet Tank Equipment indicates a residual or non-zero water level even after the tank is completely drained, it may be due to a convex or sloped tank bottom, or the close proximity of metal to the sender being misinterpreted as water. Temporarily install the sender using duct tape or masking tape to check the tank level before final positioning.
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ashley72Sep 3, 2025
What to do if Garnet Tank Equipment operation is erratic?
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  candersonSep 3, 2025
  If the operation of your Garnet Tank Equipment becomes erratic or stops completely, ensure that all wiring connections are solid. Avoid using spade connectors, as they degrade over time. Use insulated crimp-on butt connectors or solder and insulate the wire connections.
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Maria StephensonSep 5, 2025
What does 'Stacked senders' mean on Garnet SeeLeveL II 709-N2K NLP Tank Equipment?
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  John SullivanSep 5, 2025
  The 'Stacked senders' message on your Garnet Tank Equipment indicates that the display is programmed for a single sender, but double-stacked senders are connected. The display has not been configured to recognize two senders. To fix this, either change the senders or reprogram the display as needed.
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Stephanie HolmesSep 7, 2025
What does 'No top sender' or 'No bottom sender' mean on Garnet Tank Equipment?
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  tracey88Sep 7, 2025
  If your Garnet Tank Equipment display shows 'ntP' or 'nbo', it means the display is programmed for double-stacked senders, but only one sender is reporting. 'ntP' indicates only the bottom sender is reporting, while 'nbo' indicates only the top sender is reporting. Correct the programming on the sender to resolve this.

Summary

SAFETY INFORMATION

Pump and Heater Switch Safety Precaution

Details safety warnings regarding fused power circuits and potential need for relays for pump/heater switches.

OPERATION GUIDE

Reading Levels and Voltage

How to check battery voltage and tank levels for fresh, grey, black, and LPG.

Calibration Procedures

LPG Sender Calibration

Step-by-step guide to calibrate the LPG sender, requiring the LPG tank to be full.

Alarm Configuration

Program Alarm Set Points

Detailed steps for programming high/low alarm set points for each tank.

Display Modes and Sender Management

Primary;Secondary Display Setup

TROUBLESHOOTING GUIDE

Error Codes and Sender Diagnostics

Lists error codes and explains sender signal power/height diagnostics.

Wiring Diagnostics - Open Circuit

Open Circuit Troubleshooting Flowchart

Flowchart to diagnose and resolve open circuit issues in sender wiring.

Wiring Diagnostics - Short Circuit

Short Circuit Troubleshooting Flowchart

Flowchart to diagnose and resolve short circuit issues in sender wiring.

Troubleshooting & Installation Tips

System Unresponsiveness and Erratic Operation

The SeeLevel II™ is a series of holding tank monitors designed for Recreational Vehicles, providing accurate and reliable level measurement for various tanks.

Function Description

The SeeLevel II system monitors tank levels (Fresh, Grey, Galley, Black, and LPG), battery voltage, and offers diagnostic capabilities. It uses flexible self-adhesive sender panels attached to the side of holding tanks, which auto-calibrate to the tank's height. The display unit receives information from these senders via a two-conductor wire and shows levels in percent on a 3-digit LED display.

Tank Level Monitoring:

Displays levels for Fresh, Grey, Galley, and Black tanks from 0% to 100%.
LPG (if equipped) uses an existing electrical sender and shows levels from 0% to 100%.
Continuous display mode is available, indicated by a decimal point on the right, updating once per second. This mode automatically shuts off after 5 minutes or can be manually ended.

Battery Voltage Monitoring:

Measures RV battery voltage with a resolution of 0.1 volt.
The display shows the battery level in volts.

Diagnostic Capabilities:

Senders transmit diagnostic information to detect sludge buildup, damage, or delamination.
Error codes are displayed for wiring issues (disconnected, shorted, cut) or defective sender panels.
Sender diagnostics include "Sender signal power" (indicating signal strength through the tank wall) and "Sender height" (number of receive segments).

Connectivity (Model Dependent):

Bluetooth®: Allows checking tank levels, battery voltage, and LPG levels on compatible smartphones/tablets via a free app. Includes one programmable alarm output.
RV-C Bus Communication: Compatible with RVs having an RV-C network. Senders use default source addresses (72 for tanks, 73 for LPG) and SPN-ISB instances. Includes one programmable alarm output.
NMEA 2000 Network: Model 709-N2K NLP is NMEA 2000 compatible, making tank levels and capacity available on the NMEA Bus. Reports as NMEA device class 75 (sensor communication interface) with function code 150 (fluid level).

Alarm Output (If equipped):

A single common alarm output can be programmed to indicate high/low sewage, water, or LPG levels.
Multiple alarms can be assigned to the output.
The alarm can be connected to an indicator light or used to prevent toilet use when the black tank is full.

Important Technical Specifications

Display: 3-digit LED, showing 0-100% for tank levels and 0.1V resolution for battery.
Sender Type: Flexible self-adhesive printed circuit board.
Sender Stacking: Multiple senders can be double-stacked for tank heights from 4" to 25".
Power Circuit: All power circuits must be fused. Maximum current rating for pump switch is 7.5 amps (some models 10 amps), heater switch 10 amps. Relays may be required for higher amperage pumps/heaters.
RV-C Connector: 4-pin connector (Open, CAN-Hi, CAN-Lo, Ground).
NMEA 2000 Connector: 4-pin connector (+Voltage, CAN-Hi, CAN-Lo, -Voltage).
Manufacturer Code (NMEA 2000): 873.
Product Code (NMEA 2000): 15197.
NMEA Database Version: 2.200.

Usage Features

Operation:

Reading Levels: Press the corresponding tank button (FRESH, GREY, BLACK, LPG) or BATT button. The display shows the level for about 5 seconds before shutting off.
Continuous Display: Press a tank button twice to enter continuous display mode.
Holding Display: Hold the BATT or LPG button to continuously display the reading.

Configuration:

LED Brightness: Adjustable from minimum (b-1) to maximum (b-4) by holding BATT and GREY (or BLACK for 709-2P) buttons.
Number of Senders: Programmed by holding the tank button and BATT button. Options are 0, 1, or 2 senders per tank (0 senders remove tank from RV-C/Bluetooth data).
LPG Sender Calibration: Requires the LPG tank to be full. Hold LPG and BATT buttons until "CAL" is displayed.
Tank Capacity (709-N2K NLP only): Programmed by holding the tank button and BATT button. Displays capacity in US gallons, adjustable with GREY (increase) and FRESH (decrease) buttons.
Battery Voltage Calibration: Requires a 13.0 Vdc supply. Hold BATT button while applying power.
Alarm Set Points (Bluetooth models only): Programmed by holding the tank button and BATT button. Allows setting high/low alarm points (0-99%), trip polarity (high/low level), and inclusion in common alarm output.
LPG Failure Polarity (if equipped with LPG): Configurable as "fail to full" (FEF) or "fail to empty" (FEE) by holding the LPG button.
Primary/Secondary Display Mode: Configurable for dual display systems to avoid reading errors. Primary display initiates scanning, secondary passively listens. Alarms are inactive on secondary displays.
Enable/Disable LPG Sender (RVC and Bluetooth models only): Hold LPG and BATT buttons until "En" (enabled) or "dIS" (disabled) is shown, then toggle with LPG button.
Hardware/Software Revision Check: Hold BATT and FRESH buttons to display version number (e.g., "4.10").

Maintenance Features

Troubleshooting Guide:

Error Codes:
- OPN (Open circuit): Sender unresponsive, open circuit in wiring, or sender not connected.
- Sht (Short circuit): Blue communication wire shorted to ground.
- Err (Error): Signal corruption due to bad wiring, bad senders, or multiple senders programmed the same.
- SEr (Stacked senders): Display programmed for single sender but double-stacked senders connected.
- ntP (No top sender): Programmed for double-stacked but only bottom sender reporting.
- nbO (No bottom sender): Programmed for double-stacked but only top sender reporting.
- CAL (Calibration failure): Memory failure for battery voltage or tank sender signal values.
Sender Diagnostics:
- Signal Power: "P" followed by a number (e.g., P26 for 26%). Typical is 50-60%, minimum 20%. POO is 100%. Low power indicates detached sender, sludge buildup, bad wiring, low battery, or defective sender.
- Sender Height: "h" followed by a number (e.g., h 6 for 6 segments). Indicates the number of receive segments. Fewer segments than expected means sender needs cutting or replacement.
Wiring Diagnostics Flowcharts: Detailed steps for diagnosing open and short circuits in sender wiring.
RV-C Diagnostics: FMI (Failure Mode Identifier) table for messages broadcast over the RV-C bus (DIS or OFF, ERR, BOT, TOP, NTP, NBP, SIN, OPN, SHT).

Troubleshooting & Installation Tips:

System Freezes/Unresponsive: Reboot by cycling 12V power.
Erratic/Stopped Operation: Ensure solid wiring connections (use crimp-on butt connectors or solder, not spade connectors).
Dual Display Discrepancies: Ensure both console and sender grounds are connected to a common ground circuit, not relying on metal chassis.
Readings Jump/Inaccurate:
- Check for 120VAC interference from nearby wiring.
- Ensure proper grounding of senders and consoles.
- Residual/Non-zero water level: May be due to convex/sloped tank bottoms. Reposition sender (raise for convex, measure opposite drain for sloped).
- Metal Proximity: Keep metal objects (frame, brackets, pipes) at least 2" away from the sender face.
- Tank Wall Thickness: Excessive thickness (>3/8") can cause zero readings.
- Sender Position: Ensure sender top is 1/4" to 1/2" from tank top (allowing for wall thickness) for 100% reading.
- Sludge Buildup: Clean black/grey tanks with RV liquid chemicals (e.g., Tissue Digester, Sensor Cleaner, Happy Campers Holding Tank Extreme Cleaner) if levels are inaccurate when empty.
Sender Delamination: Ensure proper tank surface preparation (clean with alcohol/acetone, smooth surface, warm tank if <60°F). Support wiring harness to prevent pulling on sender.
Protecting Senders: Apply auto body undercoat (e.g., 3M Professional Grade Rubberized Undercoating) to exposed senders. Avoid lacquer, enamel, or plastic paints.
Display Mounting: Ensure smooth, adequately sized cutout in panel. Use non-conductive mounting spacers if mounting to metal to prevent short-circuiting.
Pump/Heater Switch Protection: Adhere to current limitations (7.5A/10A). Install appropriate fuses (7.5A automotive style) on +12V red wire if not provided. Use relays for high-drain pumps.

Warranty & Service:

One-year warranty on hardware for defects in material and workmanship under normal use.
Warranty claims require contacting the installation dealer or Garnet Instruments directly for a Returned Material Authorization (RMA) number.
Returns must be freight prepaid. Repaired or replaced at Garnet's discretion.