Fuel and Neutral Light??

[Shaggy33]

Just been out on my 1999 Husky and noticed after riding for a bit that the fuel light and neutral light were both on! I filled up with fuel but but this didn't solve it!
I think the neutral was flickering which says to me the switch in the gearbox may be playing up but can't understand why the fuel light is on.
Any ideas on how to solve it appreciated.

 

[K7MDL]

Just been out on my 1999 Husky and noticed after riding for a bit that the fuel light and neutral light were both on! I filled up with fuel but but this didn't solve it!
I think the neutral was flickering which says to me the switch in the gearbox may be playing up but can't understand why the fuel light is on.
Any ideas on how to solve it appreciated.

Speaking from an '07 which might be the same as your '99, the neutral light depends a ground from your switch. So either the switch is broke, flooded, or a wire is shorted to ground (pinched).

The fuel sensor on my '07 is a thermister type (FI models are different). It is close to 1300 ohms when covered by fuel in my garage (60 degrees F). When uncovered it drops to about 40 ohms. It works by current flowing through it and heating. The fuel acts as a heat sink keeping it from heating up until in free air on low fuel condition.

When it heats up the resistance drops a lot. How much and how fast is determined by a resistor in series with the battery power. Mine is 68ohms and is located near the battery-tank area mounted in a plug.

The resistor and the sensor form a voltage divider. The speedo is connected in the middle. When the fuel level drops, the sensor heats up, the resistance drops, and the voltage in the middle drops with it, monitored by the speedo circuit.

You can connect a 12V LED lamp (Such as from Radio Shack) to the sensor wire and +V without a speedo (at the speedo connector for example) and watch the lamp light on low fuel assuming your wiring is good. When the resistance drops, it is enough to pass the small current needed for the LED to light (about 8-20 ma).

I have a full write up I added to the Husky 610 speedo thread at http://www.advrider.com/forums/showthread.php?t=482490

- Mike

 

[somesuch]

Just been out on my 1999 Husky and noticed after riding for a bit that the fuel light and neutral light were both on! I filled up with fuel but but this didn't solve it!
I think the neutral was flickering which says to me the switch in the gearbox may be playing up but can't understand why the fuel light is on.
Any ideas on how to solve it appreciated.

wondering if you figured it out. My fuel light comes on whenever the bike is neutral along with a neutral light...
the only common thing for two circuits that I see is a diode by the gauges


--Nick

 

[K7MDL]

wondering if you figured it out. My fuel light comes on whenever the bike is neutral along with a neutral light...
the only common thing for two circuits that I see is a diode by the gauges


--Nick

Feels like a wire for the low fuel light is broken and but is finding its way though the Neutral lamp. Are your lamps LEDs or bulbs?

You can measure 12V is present on the hot side of the lamps, and then measure the other side of the lamps while you switch to neutral. Things that might tell you what to look for next are if the voltages on teh ground/switch side of the lamps are the same, implying a short between them. If they are not the same, then the absolute value might tell you if the current is finding an alternate path and guesses what that alternate path might be, such as another bulb. Current won't flow back thorugh a LED lamp, hence the critical bulb question.

Example scenario: Consider the low fuel lamp and neutral lamps are both supplied by a common 12V battery supply and that supply wire is broken. This leaves the 2 lamps connected together on one side. Assume these are bulbs, not LEDs, therefore can be powered from either side. The fuel tank in later models, maybe yours, uses a thermistor supplied by a low value current limiting resistor. It can be a voltage supply to the low fuel bulb which is in series now with the nuetral bulb and the circuit is completed when you shift into neutral. You can test this further by draining the tank and causing the thermistor to heat up (no cold gas to keep it cool) and it resistance drops, which then lowers the voltage supply to the low fuel bulb. The bulb, no longer having any voltage supply will not light, regardless of nuetral or not. So simplified: With normal tank level, your low fuel comes on in neutral. Changing nothing else - draining the tank causes the both lights to go out.

If you have LEDs like the newer bikes, then the above scenario cannot happen exactly since the low fuel LED would block the reverse flow of current. I would start looking for shorts and measure things to find more clues to where the actual problem is.

Going from memory there was 2 diodes positioned to complete the conditions for the bike to start and run (clutch and run switch) and neutral was wired in common to them to bypass the diodes overiding the start switch safety switches (in neutral nothing bad can happen). The diodes are there to prevent the neutral light from coming on when these switches are operated.

I am not sure if there are any other diodes and what any other diodes might be for (from memory).

To make thing more interesting, does the fuel and neutral lights both come on when you pull in your clutch or run/kill switch and you are not in neutral? Does your low fuel light come on when NOT in neutral and you drain your tank?

 

[somesuch]

Feels like a wire for the low fuel light is broken and but is finding its way though the Neutral lamp. Are your lamps LEDs or bulbs?

You can measure 12V is present on the hot side of the lamps, and then measure the other side of the lamps while you switch to neutral. Things that might tell you what to look for next are if the voltages on teh ground/switch side of the lamps are the same, implying a short between them. If they are not the same, then the absolute value might tell you if the current is finding an alternate path and guesses what that alternate path might be, such as another bulb. Current won't flow back thorugh a LED lamp, hence the critical bulb question.

Example scenario: Consider the low fuel lamp and neutral lamps are both supplied by a common 12V battery supply and that supply wire is broken. This leaves the 2 lamps connected together on one side. Assume these are bulbs, not LEDs, therefore can be powered from either side. The fuel tank in later models, maybe yours, uses a thermistor supplied by a low value current limiting resistor. It can be a voltage supply to the low fuel bulb which is in series now with the nuetral bulb and the circuit is completed when you shift into neutral. You can test this further by draining the tank and causing the thermistor to heat up (no cold gas to keep it cool) and it resistance drops, which then lowers the voltage supply to the low fuel bulb. The bulb, no longer having any voltage supply will not light, regardless of nuetral or not. So simplified: With normal tank level, your low fuel comes on in neutral. Changing nothing else - draining the tank causes the both lights to go out.

If you have LEDs like the newer bikes, then the above scenario cannot happen exactly since the low fuel LED would block the reverse flow of current. I would start looking for shorts and measure things to find more clues to where the actual problem is.

Going from memory there was 2 diodes positioned to complete the conditions for the bike to start and run (clutch and run switch) and neutral was wired in common to them to bypass the diodes overiding the start switch safety switches (in neutral nothing bad can happen). The diodes are there to prevent the neutral light from coming on when these switches are operated.

I am not sure if there are any other diodes and what any other diodes might be for (from memory).

To make thing more interesting, does the fuel and neutral lights both come on when you pull in your clutch or run/kill switch and you are not in neutral? Does your low fuel light come on when NOT in neutral and you drain your tank?

Thank you K7MDL for a very helpful post. I will check all those things out and post back on what I find.

I have not had the time to work on the bike yet, but cursory look at the wiring diagram showed that both lights share common power, and there is a respective switch that completes the circuit to ground for neutral and fuel level lights. There is also a diode from the switch side of the fuel light bulb to the switch side of the neutral light bulb!

That would turn on both lights if the neutral switch is closed and completes the path to ground!? I will double check that on the bike but it makes no sense to design it such that both lights would be on in neutral.....I must be overlooking something....

--Nick

 

[K7MDL]

Thank you K7MDL for a very helpful post. I will check all those things out and post back on what I find.

I have not had the time to work on the bike yet, but cursory look at the wiring diagram showed that both lights share common power, and there is a respective switch that completes the circuit to ground for neutral and fuel level lights. There is also a diode from the switch side of the fuel light bulb to the switch side of the neutral light bulb!

That would turn on both lights if the neutral switch is closed and completes the path to ground!? I will double check that on the bike but it makes no sense to design it such that both lights would be on in neutral.....I must be overlooking something....

--Nick

So those are bulbs and not LEDS? The diodes may be there to prevent reverse current flow from the low fuel sensor power supply. Also diodes would block the current from flowing between the bulbs, allowing current to flow only from the power supply (battery via ign switch). Looking at a 1995 and 2007 schematics, I do not see these diodes. Is this a stock speedo?

 

[somesuch]

So those are bulbs and not LEDS? The diodes may be there to prevent reverse current flow from the low fuel sensor power supply. Also diodes would block the current from flowing between the bulbs, allowing current to flow only from the power supply (battery via ign switch). Looking at a 1995 and 2007 schematics, I do not see these diodes. Is this a stock speedo?

The speedo is stock, and it uses regular bulbs. I verifyed that there is indeed a diode in there. It is located in the lover shell of the second from the left (as sitting on the bike) connector in front of the gauges.

It appears on the following schematic as well (it is a 2003, but now I could not find the 2000)
http://www.beavercreekcycle.com/Husky Manuals/Service/2003 610 Repair.pdf


All the wire colors/circuits appear the same. It seems the design is such that when in neutral both lights should come on, the neutral and the low fuel level! Not sure why Husky did it this way.

The only reason I was looking into that, is that I finally got the spark (I just bought the bike not-running/no-spark) but I still can not seem to start the thing, it just backfires into the carb.


thank you Mike for all your help. I really appreciate it.

--Nick

 

[K7MDL]

I looked at the schematic you linked. Looks like analog tach and Speedo guages, and bulbs, so old school electrics on the 2003 and earlier.

I see that diode putting the Neutral lamp and Low fuel lamps in parallel. I cannot imagine any reason for that. The only thing it would do is provide more current flow through the neutral switch (reliability?).

The diode will cause the low fuel light to come on when in neutral as you have found. So it is by design. Why? You would have to ask them. I cannot see any protection reason since the bulbs share the same power wire and the diode does nothing when not in neutral (no ground path).

The low fuel sensor is a switch rather than the modern thermistor. It goes to ground and turns the light on for low fuel.

So you get low fuel for low fuel and neutral both.

At least low fuel does not turn on your neutral light!

I would remove the diode myself. At worst your neutral switch sees less current, has high contact resistance, becomes flaky and fails to turn on your neutral lamp someday. There will be lots of current through the neutral switch when the start switch is pressed. The clutch switch bypasses the neutral switch and will allow the engine to start with the starter motor.

Looks like a cheap factory fix for flaky neutral switch reports.

- Mike

 

[somesuch]

Mike,

I was replacing light bulbs and realized that all the light bulbs could be "tested" in the gauges, but the fuel level one! so that is why Husky has it this way... it is a bulb check for the fuel light, I think....


--Nick