[antjciulla]

I’ve searched around and can’t seem to find anything I’m experiencing. My 2006 f250 fuel gauge always reads empty. Like below the red line even after a fillup. I was suspecting the fuel sending unit had gone bad from sitting before I bought the truck, but I finally got ahold of a multimeter and checked the resistance on a 200ohm scale of the actual sending unit and I’m getting 124 ohms of resistance. This number sounds about right since I filled up about 70 miles ago and the full tank ohm is 180. So do I have a wiring issue between the tank and the gauge or what should I check for. I appreciate any help.

 

[Hydro]

possible it is the gauge
when you key on does the gauge move at all?
tap your finger on the glass on front of the gauge -- does it move?
the glass sits real close and sometimes the needles will bind up on the glass
if this is the case a "gentle" push/tap will sometimes push the needle farther onto the gauge stem and free it

can also put the instrument cluster into self test and force gauge movement to full stroke

 

[antjciulla]

possible it is the gauge
when you key on does the gauge move at all?
tap your finger on the glass on front of the gauge -- does it move?
the glass sits real close and sometimes the needles will bind up on the glass
if this is the case a "gentle" push/tap will sometimes push the needle farther onto the gauge stem and free it

can also put the instrument cluster into self test and force gauge movement to full stroke

yes the needle moves up to e then falls when the glow plugs are running. I’ve also done a diagnostic gauge sweep and it moves beautifully!

 

[ChrisSki]

Not sure where you're reading it from, but here are some 2004 wiring diagrams: Hi-res Single Page 6.0L Wiring Diagram PDFs

If its possible to do the reading from the instrument cluster connector and it reads good, Circuit Board Medics has recovers an instrument cluster at reasonable prices.

The only thing I can say is just trace the wiring diagrams and maybe you'll see a relay the signal goes through or a point to check.

 

[antjciulla]

Not sure where you're reading it from, but here are some 2004 wiring diagrams: Hi-res Single Page 6.0L Wiring Diagram PDFs

If its possible to do the reading from the instrument cluster connector and it reads good, Circuit Board Medics has recovers an instrument cluster at reasonable prices.

The only thing I can say is just trace the wiring diagrams and maybe you'll see a relay the signal goes through or a point to check.

I have a spliced wire run from the sending unit into the cab and the ground attached to the frame. In the morning I’ll pull the cluster and see if I can bypass the original and get it to work. If so I’ll clean it up. Honestly I’m just glad it’s not the $300 sending unit like I thought it was the last year. I bought the truck last November and the gauge hasn’t worked since I bought it.

 

[antjciulla]

For further context, when I bought the truck there were wires cut behind the fuse box (not the upfitter switches, because I’ve already done the high idle mod), and it had this weird button with a red led screwed to the kick panel that covers the fuse box and stuff. Now that I’ve been tracing that damn yellow wire with the white line I see it’s cut down there I just can’t find where it leads to. Before today I didn’t know that was the sending unit signal wire.

 

[ChrisSki]

I guess those wiring diagrams I linked are not the detail I thought. I had a copy on CD of the wiring diagram for my truck that included wire colors, posts, connectors with pin numbers, fusible links, and references to whatever the next page of the connection. Also included what I refer to as the mystery relays on the under the dash that do sit in the fuse boxes, but unfortunately that CD stopped working.

A 2006 wiring diagram in that detail would be perfect for what you're looking for. Unfortunately, these wiring diagrams are quite pricey.

 

[antjciulla]

I guess those wiring diagrams I linked are not the detail I thought. I had a copy on CD of the wiring diagram for my truck that included wire colors, posts, connectors with pin numbers, fusible links, and references to whatever the next page of the connection. Also included what I refer to as the mystery relays on the under the dash that do sit in the fuse boxes, but unfortunately that CD stopped working.

A 2006 wiring diagram in that detail would be perfect for what you're looking for. Unfortunately, these wiring diagrams are quite pricey.

Sadly they are so I’m not all to sure what’s been cut / spliced down there. Everything functions pretty good so I don’t think anything important outside of the sending unit wire. It’s a pesky thing because apparently it jumps through a bunch of different harnesses to make it’s way up to the cluster.

 

[antjciulla]

Still not working. Reran the wire to the pcm and I’m getting a good reading of resistance there. There are no frayed wires out of the loom that goes up to the cluster. I tried grounding it to the frame. At this point I’m so confused. I can go into gauge diagnostics and the gauge will sweep properly but it’s just not displaying the fuel level. Currently I can read the resistance at around 100 ohms. Everytime I drive it goes down so I know it’s working properly. All my other gauges works so I’m so confused.

 

[Hydro]

Im confused -- why are you looking at the PCM for the fuel sender wire?

 

[antjciulla]

Im confused -- why are you looking at the PCM for the fuel sender wire?

via the diagram it shows that it goes through the pcm, or right there next to it. I tried directly hooking that wire up to the cluster and still had no reading. Any tips or anyone know more then me?

 

[Hydro]

the wire does go in the main truck harness, but it does not stop at the PCM -- it continues up to the instrument cluster
are you looking at a diagram for the '06?

should be looking for a Black/Orange and Yellow/White at the instrument cluster

 

[antjciulla]

the wire does go in the main truck harness, but it does not stop at the PCM -- it continues up to the instrument cluster
are you looking at a diagram for the '06?

yes. It may just be the connected that’s right next to the pcm. It comes up the loom, connects to another loom and enters the main harness. Either way it doesn’t work when it’s directly connected to the cluster so I’m not sure what to do from here.

 

[Hydro]

The diagram I have is from a 2004, the instrument cluster has three connectors, whereas the 2006 has two connectors -- the wire colors may be the same though
you are looking for a Black with Orange and a Yellow with White

 

[antjciulla]

Yeah I’ve got the yellow and white completely rerun. Maybe I need to do the same thing to the black and orange (ground I’m presuming).
this is the color diagram:https://www.transferflow.com/pdfs/Ford Sending Unit Wire Colors.pdf

 

[Hydro]

the fuel gauge is on a regulated circuit, so the instrument cluster provides both hot and ground
looks like the black and the yellow are next to each other in the connector at the instrument cluster
I would check continuity of the wires from the cluster to the sender -- also for connection to frame ground, as this would affect the gauge

a resistor across the terminals/wires of somewhere between 70 and 200 would activate the gauge
you could use a potentiometer or a dash light bulb would possibly work, if you do not have a dedicated resistor

 

[Hydro]

Here is a snippet of the '04 diagram

 

[antjciulla]

Thank you! I’ll try that when I get off. Pain in the butt pulling the cluster but I want my gauge to work 😂.

 

[Hydro]

Cluster is not that hard if you take the dash part completely off
tilt the cluster out at the top and remove the connectors -- yes it will tilt
the remove the shift indicator

you can then reconnect the cluster with it laying out on the steering column

 

[antjciulla]

Cluster is not that hard if you take the dash part completely off
tilt the cluster out at the top and remove the connectors -- yes it will tilt
the remove the shift indicator

you can then reconnect the cluster with it laying out on the steering column

Ill give that a try!