Ohm Meter

[REDROCKER652002]

OK. I have done a quick search and am having problems. So I am going to throw myself on the sword here. I have a Craftsman Multi Meter with an Ohm setting. I have been fighting a gas gauge issue and am trying to eliminate all possibilities. Having never used the Ohm function, I am not sure what is going on. I put the Meter on 200OHM setting. Touch the two poles of the gas gauge, which is stock and out of the cluster. The gauge shows a reading but instantly drops until it reads 0. What am I doing wrong here? Please, somebody give me a clue. LOL.

Thanks to all,

RR

[dmjlambert]

When you use the ohms function on a multimeter, the multimeter will send voltage through whatever device you are reading. So, if you're connecting to a fuel gauge or other instrument, it will cause the instrument needle to move.

Regarding the readings on the multimeter itself, some times you may get a certain reading and move the probes around a little and the reading will change. This is because as you move the probes, the tips of the probes are piercing through a layer of dirt or corrosion and making contact with good bare metal of the wire or terminal.

To find out if your sender is good, you can remove it from the tank and put it on a workbench. Hook up the multimeter probes to the terminal on the sender, and to the round metal body of the sender where it contacts the tank. Then put the multimeter on the 200 ohm range setting and move the float arm. It should go from about 90 ohms when the float is high, to near 0 ohms when the float is low (toward the bottom of the tank).

A handy thing to have to help with this activity is alligator clip test wires, which you can get at electronic stores such as Fry's, or online, or even car parts stores such as O'Reilly has them. They are a short piece of wire with an alligator clip on each end.

[Getter-Done]

Try testing on the 20K setting.
This will give you a reading of 0.00 with both the leads touched together.
The 20 200 and 2000 settings just move the decimal point.






.

[dmjlambert]

Here is a thread with good information about the fuel gauge and sender from high octane forum member TBONE1964
http://67-72chevytrucks.com/vboard/s...d.php?t=640615

[REDROCKER652002]

OK. Thanks to all who posted. I first must tell you all that I am not the sharpest tool in the shed, so to speak. LOL.

I cleaned off the terminals with some steel wool, set the meter to 20k and tried again. By touching both the left and the right terminals I was getting a .04 reading. When I touched each of the left and rights with the bottom terminal I got about a .10. So maybe I just had the meter too high? Either way, it is nice to see it doing what it is supposed to do. LOL.

I will take the sender out later on in the week. I work nights and am going on duty tonight.

Thanks to all who helped. Appreciate it.

[REDROCKER652002]

Originally Posted by dmjlambert

Here is a thread with good information about the fuel gauge and sender from high octane forum member TBONE1964
http://67-72chevytrucks.com/vboard/s...d.php?t=640615

Thanks for the link. I had seen that one, but I don't have the sender out yet to check it. I was just getting frustrated with the meter and wondered why I could not get the readings you all were able to get. I do appreciate it, and will reference that later on in the week when I get the sender out and check it.

[dmjlambert]

If the sender and gauge work outside of the truck with test leads connecting them together, then your next suspects would be the truck wires, fuses/fuse panel, and printed circuit on back of the instrument cluster.
Here is the truck wiring diagram:
http://67-72chevytrucks.com/vboard/s...27#post9186727
And here is the wiring of the instrument cluster (gauge cluster):
http://67-72chevytrucks.com/vboard/s...36#post7630636
I don't know much about a warning light cluster as my truck has a gauge cluster. You didn't mention which you have. The truck wiring diagram is a little difficult to read if you have a gauge cluster, because it is oriented for the warning light cluster and the gauge cluster connector is off to the side as if it was added as an afterthought.
Fuse box info:
http://67-72chevytrucks.com/vboard/s...98#post8004798
http://67-72chevytrucks.com/vboard/s....php?p=8562654

Probably too much info, I don't mean to over do it. I guess I better go do some chores.

[REDROCKER652002]

Originally Posted by dmjlambert

If the sender and gauge work outside of the truck with test leads connecting them together, then your next suspects would be the truck wires, fuses/fuse panel, and printed circuit on back of the instrument cluster.
Here is the truck wiring diagram:
http://67-72chevytrucks.com/vboard/s...49#post7809749
And here is the wiring of the instrument cluster (gauge cluster):
http://67-72chevytrucks.com/vboard/s...36#post7630636
I don't know much about a warning light cluster as my truck has a gauge cluster. You didn't mention which you have. The truck wiring diagram is a little difficult to read if you have a gauge cluster, because it is oriented for the warning light cluster and the gauge cluster connector is off to the side as if it was added as an afterthought.
Fuse box info:
http://67-72chevytrucks.com/vboard/s...98#post8004798
http://67-72chevytrucks.com/vboard/s....php?p=8562654

Probably too much info, I don't mean to over do it. I guess I better go do some chores.

Never too much info. Thanks for the post. I am going to pull the sender out and try it now that I have a handle on the tester and how I should have it set. I am getting an understanding of this now, and I think the sender or a ground to the tank may be the culprit. The printed circuit board is new, but certainly not ruled out as of yet. My son would really like to get the stock guages working so this is a good start.

Thanks to all who posted a reply Appreciate any and all info.

RR