Hey guys, LONGGG time lurker but I think this is my first actual post. I have read Johnny Hotspur's whole rebuild thread (which was simply amazing) and I'm hoping someone knowledgeable can help me.

I have an 07' Flying Spur that I bought that needed an engine. We replaced the engine (twice), so I am no stranger to this car. I also have two 05' GT's that I will be redoing in the future, but alas, onto my 07'..
So my fuel gauge is dead (although it did come on one day for 5 min and then went dead again)...When I read the instrument cluster module with my Autel scanner, I get an error that says no connection with fuel level sensor 4. When I read live data, I can see the 3 other fuel sensors reporting around 5 gallons and the 4th is 0....Also, the ohms readings on the first 3 are between 70-72 ohms and the 4th is reading 510 ohms....
I looked and saw that this car has four fuel level sensors, two that look cylindrical, and two that look like lever arms with floats...
Does anyone know which one Sensor 4 is?
Also, anyone have any trouble shooting tips like ways to determine whether it is the fuel sensor, the wiring, or maybe the module itself?

Thanks!

 

Anyone? Nobody knows which fuel level sensor is #4?

 

Hello @tmobileguy ,
Here are some wiring diagrams and part numbers for the floats, being that you have a fault for float number 4, it will be on the left side facing the trunk, and being that float 4 / C00236 / G393 is listed as "lower", it will be as shown as number 5 on the parts diagram, as the lower unit is the rod with float attached, and not the cylinder float.

I would also check the connections on both sides of the left connection plate shown as number 6 on the same parts diagram, as I also had float and pump issues during my GT rebuild, and it turned out to be just the plates, as all worked after the swap, I tested the connections of the blades on each side with an ohm tester, and they showed open.

Johnny

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Thank you for the reply Johnny. Extremely helpful! Couple more questions...

So I pulled each plug from both of the fuel pumps located in the trunk and here is what happens...
Large one on Passenger Side - Sensor 1 goes to zero
Small one on Passenger Side - Sensor 3 goes to zero
Large one on Drivers Side - Sensor 2 goes to zero
Small one on Drivers Side - Sensor 4 was at zero and obviously stays at zero....

Is there a way to test from the plug whether or from the pump whether that sensor is working or not? So I know if its the sensor or if its somewhere down the line like a wire or maybe the connection to the Instrument module?

Also is the instrument cluster the actual instrument module #17 that the computer reads the information off of? Or is there a separate module that the cluster connects to?

Again thanks...