in tank violet wire for sending unit fuel gauge

[Robert Dean]

So during my fuel pump issues and waiting for a new fuel pump and whatnot I decided to do some testing. I've come across something I'm curious about. Does anyone know if the violet wire on the in tank sending unit that goes to the fuel gauge sender goes to ground. Because it does on mine. I'm thinking that's how it works, depending on where the floater is it sends that particular signal to the actual fuel gauge in the dash. I'm just thinking about it and wondering if anyone knows if that's how it actually works for sure because I'm tired of messing with all this bullshit and I want to put it all back together for the last time and hopefully a long time. Just want to make sure everything is right before I do.

 

[Lil Truck]

The sending unit is a variable resistor actuated by the float. One end should be grounded the other end goes to the gauge. You can probably find a video on net if your curious.

 

[nwarky]

I am not a professional auto tech but my GN's sending unit is not wired as you describe yours. Purple wire is from the sending unit that connects to the pink wire in the harness that runs from inside the trunk to the dash fuel gauge. Sending unit is grounded by a black wire from the sending unit to the fuel pump assembly with the fuel tank additionally grounded to the left rear frame rail. Hope that helps.

 

[salvageV6]

If you disconnect the harness under the bumper 3 cavity plug and socket, then probe the wires that go into the tank assembly, the pink/purple wire on cavity B should read between 0 and 90, or, 0 and 120 ohms depending on analog or digital dash, reading to the cavity A wire which is black and goes directly to ground.

To recap simply an OHM meter setting on lowest scale, plug unplugged, probes on Cavity A and Cavity B on wires going into the tank.

Float runs a variable resistor to ground via those two wires up to a bridge circuit in the gauge.

90 or 120 ohm reading is full tank float up.

0 0hms or a short to ground is an empty tank float down.

According to the service manual.

 

[belsie]

In my case the factory sending unit grounds on top. As I went with a new Spectre unit it grounds thru into the tank, problem is I have been dealing with an intermittent loss of power at the pump???? I will follow with pics soon............