R56 Fuel Gauge Finally Fixed
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Joined: Aug 2015
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R56 Fuel Gauge Finally Fixed
Hello Everyone,
I searched around the interwebs like crazy and found nothing like this so I figured I would post my odd solution. I tried every other solution I could find and nothing worked.
My fuel gauge has been non-functional for a while. I had CELs for both fuel sending units. My code reader said both fuel sending units were bad. I replaced both fuel sending units and at first I got 0 carrots even though I had about 3/4 tank of fuel. I unhooked the connector going to the right side fuel sending unit and turned the ignition on (but not the engine). Then I turned it off and plugged it back in and that side started working. This takes removing and replacing the driver side pump a couple of times. This is the easiest way to disconnect it as the passenger side is harder to remove. You only need to pull it up enough to get at the connector. While you have it up trace the wires from the sending unit to the connector for the next part.
After that I checked menu 6 in the "hidden menu" it showed a reasonable ohm reading for the right side of the tank but had **.* for the left side. I was still getting a CEL P0463 for the left side fuel sending unit. After checking to make sure it wasn't hung up on anything, the connections were good, resistance was checking OK with my meter, and tearing off all of the electrical tape (even under the car) and looking for wire damage I was stumped. I checked the connections from the sending unit to the plug and from that to the wires with a probe and all checked out. So here is what finally fixed it:
I located which two wires went to the fuel sending unit at the connector from the first step.
I put the key in (engine off) and went to menu 6 and looked at the ohm reading. That way I could see real time if a loose wire or anything was the cause.
It still showed **.* for the left side.
I connected the two wires from the sending unit to each other, basically making it zero resistance using probes.
The reading changed to a full tank on that side for an instant and after disconnecting them it started reading normally.
Now I am perfectly aware that you shouldn't mess with anything like your fuel system with the battery connected but I see no other way to do this. I used sewing needles as probes as they leave a tiny hole and no wire sticking out when you are done. It is the safest way I could think of doing it. So if your ECU is "stuck" like mine this might clear it. Make sure you have the correct wires or you will break something expensive or cause a spark which would be no good. Grounding each of the wires did nothing. I tried that first.
You may be able to turn everything off and short the wires and turn it all back on but since they are only resistance wires it should be safe. Frankly after two days of pulling the battery and about 20 times pulling the sending units I was done with the whole battery disconnect for each step. Unplugging it at the top of the driver side disconnects everything anyway.
I searched around the interwebs like crazy and found nothing like this so I figured I would post my odd solution. I tried every other solution I could find and nothing worked.
My fuel gauge has been non-functional for a while. I had CELs for both fuel sending units. My code reader said both fuel sending units were bad. I replaced both fuel sending units and at first I got 0 carrots even though I had about 3/4 tank of fuel. I unhooked the connector going to the right side fuel sending unit and turned the ignition on (but not the engine). Then I turned it off and plugged it back in and that side started working. This takes removing and replacing the driver side pump a couple of times. This is the easiest way to disconnect it as the passenger side is harder to remove. You only need to pull it up enough to get at the connector. While you have it up trace the wires from the sending unit to the connector for the next part.
After that I checked menu 6 in the "hidden menu" it showed a reasonable ohm reading for the right side of the tank but had **.* for the left side. I was still getting a CEL P0463 for the left side fuel sending unit. After checking to make sure it wasn't hung up on anything, the connections were good, resistance was checking OK with my meter, and tearing off all of the electrical tape (even under the car) and looking for wire damage I was stumped. I checked the connections from the sending unit to the plug and from that to the wires with a probe and all checked out. So here is what finally fixed it:
I located which two wires went to the fuel sending unit at the connector from the first step.
I put the key in (engine off) and went to menu 6 and looked at the ohm reading. That way I could see real time if a loose wire or anything was the cause.
It still showed **.* for the left side.
I connected the two wires from the sending unit to each other, basically making it zero resistance using probes.
The reading changed to a full tank on that side for an instant and after disconnecting them it started reading normally.
Now I am perfectly aware that you shouldn't mess with anything like your fuel system with the battery connected but I see no other way to do this. I used sewing needles as probes as they leave a tiny hole and no wire sticking out when you are done. It is the safest way I could think of doing it. So if your ECU is "stuck" like mine this might clear it. Make sure you have the correct wires or you will break something expensive or cause a spark which would be no good. Grounding each of the wires did nothing. I tried that first.
You may be able to turn everything off and short the wires and turn it all back on but since they are only resistance wires it should be safe. Frankly after two days of pulling the battery and about 20 times pulling the sending units I was done with the whole battery disconnect for each step. Unplugging it at the top of the driver side disconnects everything anyway.
