Anyone ever replace a sending unit power wire ?

[pearljam724]

The blue wire is a ground signal from the sender to the gauge. The sender is grounded to the body through the fuel gauge strap that clips on the fuel line to the sender right at the front of the tank. See photo.

Every load device needs power and ground to operate whether it’s a light bulb, electric motor, or a fuel gauge. The ground signal from the sender is variable, that’s how the gauge changes it’s reading. The power is from the voltage limiter on the back of the cluster.

Just like dash lights can change their brightness from the dash light dimmer switch.

View attachment 866695

Thank you, very similar to a rheostat/dimmer switch

 

[Beekeeper]

Thank you, very similar to a rheostat/dimmer switch

exactly

 

[pearljam724]

Hey guys, back at it today with the gauge. I’ve tried hooking 2 different senders to the tank blue wire and two different limiters to the back of the gauge and grounded the sending units well. Mest with this for a couple days now and gauge will not move. Where it worked fine a few days ago.
Rather than pull speedo to check gauge itself. I ran two lead wires behind dash to gauge. I connected those leads to a small 12v battery for just a second or two and the gauge swept fine ? Would that definitely leave the problem to be the limiter ? What’s the way to test a limiter, by ohm readings ?

 

[Beekeeper]

Did you confirm 12 volts from ignition to the limiter?

 

[pearljam724]

Did you confirm 12 volts from ignition to the limiter?

I charged battery it was at 90%. But, after I charged it to 100%. The aftermarket gauge still reads at 10.5 just as before when key is in run position but engine not started. I think that’s normal because the key being turned on will draw a little voltage. I found a video on how to test limiter.

 

[Beekeeper]

Im referring to the 12 volt supply right where the limiter plugs in

 

[pearljam724]

Im referring to the 12 volt supply right where the limiter plugs in

Oh, I got it now. There is a prong on the back of limiter that says ignition. You’re saying attach my voltmeter in that same prong hole when I turn key ? If I don’t get a good reading there what else could it be ? Circuit board only ?

 

[Beekeeper]

good reading there would point to bad limiter
and yes maybe the circuit board or the connector to it

 

[pearljam724]

good reading there would point to bad limiter
and yes maybe the circuit board or the connector to it

Ok thank you. But, I was under the impression if the limiter is bad. The gauge would peg out at full. It doesn’t do that and I tested gauge. It works

 

[Beekeeper]

the limiter can fail closed or open.

 

[pearljam724]

the limiter can fail closed or open.

If that’s the case, pretty sure at this point. That’s what it is. Probably empty my bank account on a solid state one, lol !

 

[Beekeeper]

They are pricey but the work great plus have an led
to show it has power.

 

[pearljam724]

They are pricey but the work great plus have an led
to show it has power.

That’s a big incentive right there. Thank you, greatly

 

[mopar 3 B]

Check to make sure the limiter has voltage to it first or you just maybe wasting more money for nothing.

 

[pearljam724]

Check to make sure the limiter has voltage to it first or you just maybe wasting more money for nothing.

Good suggestion, but a few hours late. The limiter nearly caught on fire when testing it, lol ! I either had it hooked up incorrectly or the points were sticking. Causing it to make a big sulfuric cloud when I hooked it up directly to 12 volts and a bulb to test. Yeah, time to buy a new one, lol !

 

[dadsbee]

Here... fix it right back up. I'd say you hooked it up wrong. No reason for the regulator itself to burn up. Gauges maybe if it was stuck on at a full 12 volt output, but not the regulator just testing it with power.

 

[pearljam724]

Here... fix it right back up. I'd say you hooked it up wrong. No reason for the regulator itself to burn up. Gauges maybe if it was stuck on at a full 12 volt output, but not the regulator just testing it with power.
View attachment 867565

Funny dad, lol ! No, the limiter was removed from cluster when this happened. Shortly after I tested gauge. Gauge sweeps like it should. I believe it was limiter. I may have hooked it up incorrectly to test. I think I put its misery into overdrive. Lol ! Looking back through all of it. I think I know what happened to the limiter. It was starting to go bad to begin with and I made the sender arm go past the full stop to make gauge read full. Rather than 3/4 it was reading when tank was full. I think this burned up the limiter because that would send too much voltage. If I’m not mistaken. The gauge sweeps though.

 

[dadsbee]

You can play with your wire all day.. it won't burn up the limiter. All the limiter is is a bi metalic mechanism, like an old temperature controller. It just turns on and off as it heats and cools and gives a pulsed 5v output.

 

[pearljam724]

About 50 seconds in. My smoke cloud was pretty similiar. Without the bang, sparks and fire.

 

[mopar 3 B]

You can play with your wire all day.. it won't burn up the limiter. All the limiter is is a bi metalic mechanism, like an old temperature controller. It just turns on and off as it heats and cools and gives a pulsed 5v output.

If he directly grounds the fluctuating 5V output instead of going threw a voltmeter or some kind of resistor. The limiter acts just like a fuse. Poof and nothing.