Perplexing "FUEL" light malfunction

[zclocks]

I take that back, I did get it to work. Down load to desk top and then open.

Edited August 2, 2020 by zclocks

[zclocks]

Did you measure the thermistor to see if it has a resistance? 

[SteveJ]

5 hours ago, Captain Obvious said:

Yarb, I don't know if it's just me, but I couldn't get your video to work. It downloaded, but it was a blank screen. Probably a problem on my end, but can you do youtube instead of hosting it here on the forum?

Here you go, @Captain Obvious. I uploaded @Yarb's video to YouTube. https://youtu.be/uQcu71wOkpw

[Yarb]

I’ll measure it tomorrow when I get back to the shop. I’ll measure my replacement from ZCD as well.

[dmorales-bello]

Yarb's thermistor looks exactly the same as my original '78 unit.

Sent from my SM-N950U using Tapatalk

[Captain Obvious]

SteveJ, thanks for putting the video on youtube for me. That worked. And Yarb, thanks for the video.

So Dr. Dave, are you able to see the remains of the thermistor body down inside your outer housing? In this pic, you can see the solder blob on the outside where they made connection to the other sensor lead. You should be able to see some of that lead inside the case:

 

[Dave WM]

interesting, my OE unit (which was not working) was missing the solder on the bottom, just a hole with a wire coming out that had been bent over. I did not notice any witness marks of old solder. My fix was to solder is so now it looks like the pic above (I presume the solder came off at some point, but hard to believe unless it was poorly soldered in the 1st place). If I have the reason to pull it out again I will prob solder the side to the clip as well to prevent the corrosion from forming there on the ground side as well. Another thing I want to do is to see if I can rotate it to find out how much of an effect orientation has on the gauge reading. This is the side loaded model not the top loader. will have to wait until the gas level drops obviously.

Edited August 3, 2020 by Dave WM

[dmorales-bello]

Good morning Cap'n O,

I could not manage to snap a picture inside the can that would show what was in there with artificial lighting. With the help of some diffuse sunlight "by George I've got it". (movie reference. Trying to fit in! [emoji851]).

The only thing that's in the can is a fragment of the broken wire about 3/4" long sticking straight up from the bottom where it is still attached to a point of solder. That's it.

Is there a chance some other component of the thermistor is embedded within the plastic cap?

Hope this helps

 

Sent from my SM-N950U using Tapatalk

 

 

 

 

 

[Dave WM]

hmmm maybe the OE unit is some kind of special NTC resistance wire (if there is such a thing) and not a separate component at all?

I assumed it had to be a semiconductor of some kind, but maybe wire that is made with semiconductor material?

I will be doing an autopsy of my spare defective unit later and reply back with results.

Edited August 3, 2020 by Dave WM

[Captain Obvious]

Dr.Dave, Yep... There's the other end!

DaveWM, I assume there used to be some sort of discrete component in there, but honestly I don't know enough about thermistors to answer your good question about just a length of wire that changed it's resistance with temperature. I guess it's a possibility? Maybe?

I think it used to look something like this and the thermistor turned to dust:

I also don't think there is anything buried inside the plastic end cap. I think that's just a device to transition from the thermistor lead to the flexible wire.

Edited August 3, 2020 by Captain Obvious
Updated sketch to show ferrule

[Captain Obvious]

11 minutes ago, Dave WM said:

I will be doing an autopsy of my spare defective unit later and reply back with results.

You ought to be able to de-solder the lead from the can and then just pull the plastic cap out with the thermistor along with it. (If the whole thing isn't too fragile by now...)

[Dave WM]

Oh yes I see that end piece looks like a component of some kind was once there, I did not look at the bottom pic when I made the wire comment. Maybe a glass axial lead type.

Edited August 3, 2020 by Dave WM