Hi,

I’ve been working on my gauge sender and I’m realizing I don’t really know how to read the gauge. I took my sender apart, cleaned it and started testing it out while it was installed in the car. No jumps, needle goes up and down.

But...when I slide the float all the way down to the reserve shorting bar, the needle drops to what appears as the 1/4 tank mark. It goes no lower. I would think running the float down to the shorting bar would make the needle go to R.

My R light comes on. The needle reads full when the float is all the way up. And it gradually moves down without jumps as I slide the float down by hand. But it stops at the 1/4 marker.

I don’t know if I’ve ever run it lower than a quarter. I usually fill before that.

Is this normal for the needle not to read empty on R? Is it supposed to stop at 1/4 or has my zero drifted off after 35 years?

There’s a fixed resistor on the gauge. Perhaps I need to trim residual value and add some resistance to it to make my gauge read empty (at R).

I read my manual and it didn’t say anything about the needle going all the way down to R.

Just curious if your gauges go down to R. I recall my 240D did. My contacts at the sender look clean. Perhaps I have some residual resistance in the circuit or the needle has just drifted.

__________________
79 300TD “Old Smokey” AKA “The Mistake” (SOLD)
82 240D stick shift 335k miles (SOLD)
82 300SD 300k miles
85 300D Turbodiesel 170k miles
97 C280 147k miles