HOw to fix low fuel light?

[Gebo]

HOw can I fix the low fuel light? Mine stays on all the time.

[richtazz]

does your gas guage work otherwise???

[Gebo]

YEP.

C'mon Richtazz, I sense where you are going. Don't give me the old line of "don't worry about it." Us perfectionists make it rough enough on ourselves without having it rubbed in............

I want to know what is involved in fixing this light.

[richtazz]

I would bet that your fuel sender is going bad, or your guage cluster. The low fuel light is triggered when the needle is below 1/8 tank. The needle is just an ohm meter, changing position as the rheostat in the level sensor changes the amt of current reaching the guage. I've never had a guage package apart, so I'm not sure if the low fuel light is triggered by the current reading, or mechanically by the position of the needle (meaning that when the needle reaches a specific point in it's travel the low fuel light goes on.) IF this is the case, whatever the needle contacts to trip the low fuel light may have come off or out of adjustment, thus the working guage and malfunctioning light.

[Gebo]

So there won't be a switch or something I could simple plug/unplug and make sure there are good connections?

[NiteOwl]

Checking the U body service manual for my '94 shows that the low fuel indicator (LFI) light is connected to a solid state control (SSC) in the instrument cluster. The SSC also controls the ABS light.

For the LFI, one terminal of the SSC is grounded through the fuel sender. The fuel gage shares this variable resistance to ground and is separate. When the resistance of the fuel sender drops near 1 Ohm (empty) the SSC grounds the LFI and it lights up.

If the fuel gage works and everything else is normal, either the SSC or instrument cluster must be replaced.

[LMP]

THe low fuel indicator light is triggered by a solid state control device that receives its information from the same voltage that acts on the fuel gauge. THis solid state controller is built in the instrument cluster. IF the gauge works normally, then the controller is "kaput".

[LMP]

..sorry for the duplicate...I had not read NiteOwl 's reply....but...in my '93 book, the ABS light is triggered from a separate device.

[kingarthur2]

Originally Posted by Gebo

HOw can I fix the low fuel light? Mine stays on all the time.

My 92 Transport low fuel warning light is alway on. The auto electric shop , which repairs the alternator every 18 months( that another story) says ( take the bulb out) as finding the fault could take forever.

My solution was to stick a small black paper (adhesive) circle over the dashboard on top of the light. The light is still on but I cannot see it anymore.

[Colasont]

Mine stays on too.

[93cobra]

mines always on. The engineer musta been a rookie who designed it

[LMP]

..Well....on the engineering side, this circuit is rather simple: it is called a comparator, usually done with one single "operational amplifier" and the price of it all must be like 49 cents. However, this circuit has to drive the lamp on and carry this amount of current . My guess is that the current requirement is too close to the amplfier rating and KEEPING IT ON for a long time blows off the circuit - meaning, it becomes "shorted", acting as a straight piece of wire.
Soo............in conclusion, for those whose LOW FUEL lamp still works normally, simply do not let the fuel tank go low for long.....so the light will not blow off the circuit.

[93cobra]

Originally Posted by LMP

..Well....on the engineering side, this circuit is rather simple: it is called a comparator, usually done with one single "operational amplifier" and the price of it all must be like 49 cents. However, this circuit has to drive the lamp on and carry this amount of current . My guess is that the current requirement is too close to the amplfier rating and KEEPING IT ON for a long time blows off the circuit - meaning, it becomes "shorted", acting as a straight piece of wire.
Soo............in conclusion, for those whose LOW FUEL lamp still works normally, simply do not let the fuel tank go low for long.....so the light will not blow off the circuit.

Well, here is a guy who fixed that same problem. Check it out....http://www.w-body.com/index2.html Hope this helps Go to the W body problems section

[LMP]

Eh..good. GM does have problems with cold solder!!!I had the erratic wiper OKayed with the soldering pencil already. If my gauges go haywire, I'll go for it....and I like that solution better that the one I suspected. Thanks for the tip.