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#1
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Low fuel light on all the time
My low fuel light is always on in my 85 300D when the key is in the ON position. It was working correctly after I removed the sender and performed an internal cleaning. Worked correctly for about 1 year; then started this "on all the time" behavior. I have re-opened the sender and found a lot of gunk in the bottom of the tube; I carefully removed all of that, cleaned things up and reassembled everything. I still have an always on condition. Gauge functions fine.
Is this something that can be caused by an bad ground somewhere? If so, does anyone know where that ground point would be? TIA.
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Mike Frederick 1986 300SDL, 240K+ miles 1985 300D KaliKar, 270K+ miles |
#2
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The low fuel light contact in the tube switches to ground.
There are 3 wires running the length of the sensor. The two Ni-Cr wires are the sensing wires, these two get bridged by the slider. The single copper wire is the low fuel light wire. When the slider hits bottom it bridges two points on the bottom plate. One is from the copper wire and the other is the ground via the central support rod. Remove your first aid kit and unplug the sensor connector. Does the light turn off?
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The OM 642/722.9 powered family Still going strong 2014 ML350 Bluetec (wife's DD) 2013 E350 Bluetec (my DD) both my kids cars went to junkyard in 2023 2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles) 2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles) 1998 E300DT sold to TimFreeh 1987 300TD sold to vstech |
#3
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Yes, its stays on with the fuel sender unplugged.
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Mike Frederick 1986 300SDL, 240K+ miles 1985 300D KaliKar, 270K+ miles |
#4
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Sounds more like a good ground. Problem is, there should be no ground except when the tank is almost empty.
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When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl. |
#5
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Any more feedback?
Does anyone else have any help they can provide with this?
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Mike Frederick 1986 300SDL, 240K+ miles 1985 300D KaliKar, 270K+ miles |
#6
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How important is the low fuel light to you?
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When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl. |
#7
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When the key is put in glow position, all lights come on to verify their operation. It's possible there is a problem with the cluster board, or the ignition switch itself... Aside from that, you are looking at chasing the wiring to the cluster from the tank...
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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread "as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do! My drivers: 1987 190D 2.5Turbo 1987 190D 2.5Turbo 1987 190D 2.5-5SPEED!!! 1987 300TD 1987 300TD 1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere! |
#8
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If it still comes on with the gauge unplugged then it's either a short in the wiring harness or a blown diode in the bulb check circuit. I'm thinking the latter.
Here's a quick check, with the bulb glowing and the sender harness plug in your hand, short terminals 2 and 3 together. Does the bulb get brighter? If so it's the cluster, if not, it's probably a short in the wiring. The cluster bulb check glows the bulb dimmer than when the light is actually actuated (there is a resistor in series with the diode to cause this). The diode will be on the circuit board on the F-O-T gauge part of the cluster. If you are really handy with electronics and know how to solder, you could probaby find and replace the bad diode. If not, go to the junk yard and grab a 124 cluster. Gas or Diesel does not matter. Turn the cluster over and carefully remove the module for the fuel-oil-temperature gauges. If it's a gas leave the other two (speedo and tach) as they are useless on a Diesel (wrong diff ratio on the speedo and wrong pulse multiplier on the tach). Bonus: If you got a gas model gauge cluster you can search for Sixto's economy to boost gauge mod on this forum and hook up the economy meter as a boost gauge.
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The OM 642/722.9 powered family Still going strong 2014 ML350 Bluetec (wife's DD) 2013 E350 Bluetec (my DD) both my kids cars went to junkyard in 2023 2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles) 2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles) 1998 E300DT sold to TimFreeh 1987 300TD sold to vstech |
#9
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' low fuel light on all the time'......
The obvious answer is ' TO STOP DRIVING AROUND with only 2 GALLONS of fuel in the tank '... LOL
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1980 240d , chain elongation, cam marks reference: http://www.peachparts.com/shopforum/showthread.php?threadid=10414 http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html evap fin cleaning: http://www.peachparts.com/shopforum/showthread.php?t=156207&highlight=evaporator A/C thread http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html |
#10
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If you have nothing intelligent to offer then offer nothing.
This is not what the OP is asking. The problem is probably in the plug or in the dash if the light does not go off when unplugged. Do what jay suggested.
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Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed. W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html 1 X 2006 CDI 1 x 87 300SDL 1 x 87 300D 1 x 87 300TDT wagon 1 x 83 300D 1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry. |
#11
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Add fuel.
(Just being a smart a$$, sorry......) Dan |
#12
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Pop the plug connector apart that plugs into the sender and see if there is anything bridging the pins together..
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