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Discussion Starter · #1 ·
Hi guys,

I am replacing my gauge cluster with a Dakota Digital gauge. It does not have a fuel gauge, so I decided to add a low fuel light (if possible).

I have a basic indicator light which is an LED with two leads.

I understand that the fuel gauge works based on resistance. Does the Vrod (2007) work on that principle? Also, how do I connect an indicator light to that wire so that it lights up when the float is at a specific point?

Thank you in advance for your help. :cheers:
 

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...
...I am replacing my gauge cluster with a Dakota Digital gauge. It does not have a fuel gauge, so I decided to add a low fuel light (if possible).

I have a basic indicator light which is an LED with two leads.

I understand that the fuel gauge works based on resistance. Does the Vrod (2007) work on that principle? Also, how do I connect an indicator light to that wire so that it lights up when the float is at a specific point?...
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Starting in 2007 the VRSC fuel level gauge switched to a sonar "time of flight" level sensor. The IM (instrument module) provides both the driver for the sonar tube and the readout circuitry that interprets the voltage signal from the sensor. I can't think of any way that this level sensor can be used without the IM circuitry.
 

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...I made a typo in my post and the bike is a 2006. So I am pretty sure that is that standard resistant float system.
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Even the older variable resistor version would require a non-trivial special circuit design with a regulated voltage source and additional solid-state components to trigger your LED warning light. You might be able to use one designed for automotive applications since the early fuel level sensor is similar to that used for cars. The VRSC sender used from 2002 to 2006 has a resistance of ≈ 50 Ω when full and 300 Ω when empty. The low fuel light goes on when the resistance rises to ≈ 150 Ω.

In the linked device you would connect the Y/W (yellow with white stripe) wire from the sender to the TAN wire of the device. The other wires are pretty straight forward:
BLACK goes to a ground wire (most black wires on the bike but make sure by testing).
PINK goes to a fused power source. I'd connect to the O/W (orange with white stripe) accessory circuit wire.
YELLOW goes to the negative side of your LED. The other end would connect to the O/W wire (or whatever other wire you use to power the device).​
I haven't tried this so there's no guarantee it will work. The description and instructions don't mention what the fuel level sender resistance should be nor does it mention what type of light it uses but I think it's an amber LED.

After looking a little more, I found another source in England (but it looks like they ship to the US). The company is Spiyda and they sell several versions:
Miniature version with pigtail leads.
Miniature version with screw terminals.
Enhanced version with high output (over kill).

They provide pdf installation instructions and from what I can read this should work with the VRSC resistive sending units. (The sender has high resistance when empty).
 

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Discussion Starter · #5 ·
Thank you!

I understood that there was a resistance factor, It looks to me that when the resistance rises to a specific point the device completes the circuit to the light.

Can I measure the ohms from the sender to calculate when I want the light to go off?
I replaced the tank with the larger version from Unlimited Engineering so the light on the fuel gauge goes on a bit early. I am assuming that when the resistance rises to 150Ω, the float is not necessarily slightly passed half way or 3/5.

Then try to find a device that will fit?

I get that this is all hypothetical, along with the assumption I can find a device with the specific specs I am looking for.

Thanks again
 

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Discussion Starter · #7 ·
Yes, and thanks again. I noticed that after you mentioned it.

I did do a little research and the device is called a comparator circuit, or at least based off of that design.

They are way cheaper on ebay and such than the lower fuel warning "module" that they are selling, but it is not completely clear on how those work.

Thanks again! You were really helpful. I will try to post how it all works out.
 

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Discussion Starter · #8 ·
Just an update on this project.

The gauge is mountable and wired up but I can not get a reliable fuel light.

The spydia product while it seemed promising does not work reliably, and I can't figure out why. I have contacted their "tech support" and while the guy Chris was trying his best to be helpful in confirming all of my assumptions, the module does not adjust reliably at all.

I know I could just use the odometer, but that will annoy me at this point.

I have lost a bucket of time trying to get this to work and I have become a bit discouraged.

https://drive.google.com/file/d/175PoHHA54EvzT9ZNbhPvnOELQSIIwAkY/view?usp=sharing
 

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Mromaus. I assume you are using the stick and float from the older V-Rods for your level indicator. If yes, then a post by Steppenwolf shows how to correct a design flaw in it which results in erratic readings. Here is a LINK to that post.
'
Be aware: DO not let the float fall off the bottom of the stick or you will destroy some very delicate electrical contacts inside the float. The bottom of the stick has a hole in it. Stick something in that hole to prevent the float from falling off.
 

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Discussion Starter · #10 ·
Thanks Rusty for the help.

I am not convinced this is the issue here, since I manual move the float and the resistance changes reliably and predictably.

The issue seems to be the comparable circuit that does not adjust reliably. If I place the float at full which is at 65 ohms, or empty 260 ohms the light remains on. I wired the circuit as instructed so that it reacts to high resistance.

The module supplies power to the ground until resistance increased. Once the resistance increases to a specific level the module is supposed to cut power to the ground allowing the light to turn on. If the light is on and I move the float to full reducing the ohms, the module does not seem to be cutting the voltage to the ground.

I thought of some different considerations to mount the phone with use of the original gauge. After my last post of frustration.

This is $600 worth of stuff and I can't seem to complete the project because of this one issue. If I can't get this to work I will just have to sell the stuff to try to make some money back I guess. Thankfully I did not cut up the harness and made a plug for the gauge, so it directly plugs into the original receptacle.


Any one interested in a Dakota Digital 3016 gauge? Pre wired plug and play? ?


Thanks guys, I have given up yet, but I'm getting there.
 

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Thanks Rusty for the help.

I am not convinced this is the issue here, since I manual move the float and the resistance changes reliably and predictably.

The issue seems to be the comparable circuit that does not adjust reliably. If I place the float at full which is at 65 ohms, or empty 260 ohms the light remains on. I wired the circuit as instructed so that it reacts to high resistance.

The module supplies power to the ground until resistance increased. Once the resistance increases to a specific level the module is supposed to cut power to the ground allowing the light to turn on. If the light is on and I move the float to full reducing the ohms, the module does not seem to be cutting the voltage to the ground.

I thought of some different considerations to mount the phone with use of the original gauge. After my last post of frustration.

This is $600 worth of stuff and I can't seem to complete the project because of this one issue. If I can't get this to work I will just have to sell the stuff to try to make some money back I guess. Thankfully I did not cut up the harness and made a plug for the gauge, so it directly plugs into the original receptacle.


Any one interested in a Dakota Digital 3016 gauge? Pre wired plug and play? ?


Thanks guys, I have given up yet, but I'm getting there.
Are you giving the unit sufficient time to stabilize between adjustments? They have an anti-slosh function that will require you to wait 3 minutes in between any adjustments made.
 

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Stppenwolf's fix resolves a issue of erratic readings. Two Copper? plates, one just lays on top of the other, get electrically dirty resulting in erratic readings. Soldering the connectors together cured my erratic problem.
 
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