JCB 3CX Fuel Level Sender

[Spancan]

The fuel gauge on my 1984 JCB 3CX model 297348 does not work. Not sure whether it is the gauge or fuel level sender. Does anyone know how to replace sender ( they are cheap enough from Vicary Plant at £30). There appears to be a circular inspection plate at the base of the diesel tank, however there are no electrical wires or any signs of electrical connections ?

[gecko.cx]

Start by checking Fuse 12 - could be an easy fix.

Do you have a test light or multimeter?

Can you get to the back of the gauge?
There should be three terminals: One terminal will be 12V (Green), one to ground (Black), the other will go to the sender (Green with a Blue Trace).
If you short the sender line to ground, the needle should respond convincingly.

If the gauge doesn't respond, it's probably failed.

[mechman]

Spancan
Same prob on my 84 3cx. changed the sender unit. There's a plate on top of the diesel tank to the left of the dash. just a little bit fiddly. I got the unit from Vicary Plant.
Norm.

[Spancan]

Checked fuel gauge all ok. How do you access sender unit ?

[Spancan]

Thanks Norm, do you access it from inside the cab or outside ?

[mechman]

Inside. There's an access hole at the back of dash to the left in the steelwork, the hole on mine was a bit off centre to the sender unit so I opened it up with a die grinder, made life easier.You will have to remove a couple of dash panels to access it. Once you gain access it's a straight forward job.
Norm.

[Spancan]

Thanks for that Norm. I have found it after taking all the dash off. I found that the sensor wire has corroded away, however the gauage does not work when I touched the sender wire to the brass screw which suggests a new sender unit is required. It looks that I might struggle to get plate off with all the corrosion. (See below)

[mechman]

The screws on mine looked that way but they came out, (gently does it) The float had disappeared on mine. Got the new one from Vicary plant it came with a separate earth tag. Ignition on, earth the lead from the gauge to the sender unit the gauge should read full, that proves the gauge is OK.
Norm.