Recently my TC35D ('03/750 hrs) fuel gauge was showing the actual fuel level, and then while driving, it would peg full. Now if just pegs full every time it is started. Trying to understand if it's the sending unit or a wire issue. Wondered if anyone has experience with this? I have removed the unit from the tank while wired up, and tried to "manually" position the arm so it's empty, but no response on the instrument cluster. I can buy a new sending unit I guess, and try it before I place it inside the tank to see if it works, but would rather here from someone that maybe had similar issues...... I can hear and see that the "ribs" are being contacted on the sending unit by the arm movement, which I think it just measuring resistance, not sure.
NH TC35D Fuel sending unit always pegs full
- Thread starter srodster
- Start date
dlctcg
Platinum Member
@srodster -
See Attached PDF's for testing procedures for the fuel gauge & fuel sending unit... It should help narrow down the problem prior to just buying parts.... These are from the NH Repair Manual for the TC35D / TC40D / TC45D...
Also do not rule out a compromised or broken wire... but these PDF's should help narrow that down...
See Attached PDF's for testing procedures for the fuel gauge & fuel sending unit... It should help narrow down the problem prior to just buying parts.... These are from the NH Repair Manual for the TC35D / TC40D / TC45D...
Also do not rule out a compromised or broken wire... but these PDF's should help narrow that down...
Hughman
Gold Member
Had this happen on an old RV. I'd I remember correctly, a bad or broken ground wire will cause the gauge to peg on full.
Thanks, an update.
1) I disconnected the wires to the sending unit and removed it, and got 33 ohms (full/all the way up), and 253 ohms (empty/all the way down). Conclusion = sending unit ok
2) With the wires still attached to the sending unit, I ran another ground wire straight from sending unit to battery, and no response on fuel gauge. And even disconnected the neg blade wire and only ran my new wire to the neg of battery, and no response.
3) I removed the instrument cluster and with fuel gauge still attached measured between pin 14 & 21, and had 83 ohms, (manual says 70 to 80 range, so conclusion = ok so far) Measured between pin 14 and 24, and had 589 ohms, (outside of either range on high side, so maybe fuel gauge?)
4) I removed the fuel gauge from the instrument cluster and measured the lower left and lower right sockets and got 82 ohms, (within range of 75 to 87 ohms) I then measured upper left and lower right sockets and got an open circuit, (conclusion FUEL GAUGE needs replaced)
I certainly appreciate the help here! I will see how soon I can get a new fuel gauge, and report back!
I believe part #86540853.
1) I disconnected the wires to the sending unit and removed it, and got 33 ohms (full/all the way up), and 253 ohms (empty/all the way down). Conclusion = sending unit ok
2) With the wires still attached to the sending unit, I ran another ground wire straight from sending unit to battery, and no response on fuel gauge. And even disconnected the neg blade wire and only ran my new wire to the neg of battery, and no response.
3) I removed the instrument cluster and with fuel gauge still attached measured between pin 14 & 21, and had 83 ohms, (manual says 70 to 80 range, so conclusion = ok so far) Measured between pin 14 and 24, and had 589 ohms, (outside of either range on high side, so maybe fuel gauge?)
4) I removed the fuel gauge from the instrument cluster and measured the lower left and lower right sockets and got 82 ohms, (within range of 75 to 87 ohms) I then measured upper left and lower right sockets and got an open circuit, (conclusion FUEL GAUGE needs replaced)
I certainly appreciate the help here! I will see how soon I can get a new fuel gauge, and report back!
I believe part #86540853.
Thanks for all the replies! A new fuel gauge arrived today from Messick's, and that was the issue. Installed it and tested it prior to install, and everything is good to go....., However, that was a tough invoice, conveniences of life......., $192. I could have played a lot of scratch off's for that and just made sure the tank was full each time...., ha.... Appreciate all the help!!!