Ohm reading across ammeter terminals

[4mulas]

Hoping someone has a working ammeter outside of the car that they can test what the ohm rating is between the terminals.

Just doing some trouble shooting and would really like to know. I had power in the car, lost power in the car and have trouble shot it to the ammeter. Fuse link is good, goes through the bulkhead fine and then into the ammeter but not out. Upon further examination the black terminal was little loose, when I tested with the ammeter there was no reading, centred the post terminal of the ammeter, tightened it and now I have continuity.. did and experiment and loosened the terminal more than initially found and it had rather high resistance in ohms. Took my time, centred the terminal and tightened it again a now had nice low ohm reading of .3 I’m considering using the ammeter again or also considering bypassing it and being done with it in case it is suspect..

Regardless if someone can give me a reading in ohms on a known working ammeter I would appreciate it.

Thanks

 

[Nacho-RT74]

Make a search and will find several threads about. On one of them its explained the internals of the ammeter and why, how and where they could fail. Also how to fix it. They are not old threads since we have got several hard discussions about them in the last year and they float on quite often.

The ammeter is a close to zero resistance path, unless something is really wrong internally.

 

[kiwigtx]

The ammeter is a close to zero resistance path, unless something is really wrong internally.

Correct....almost a dead short across the terminals.

BTW.....NEVER try and measure the resistance of a battery.

 

[mrhemi]

Ok, from a -40 to 0 to +40 Rally dash ammeter, 0.2 ohms across the copper bus. As noted in previous comments, the resistance at the terminals can vary greatly depending on the quality of the connection of the terminal studs to the bus. The .3 ohms you get after you tightened the terminal is probably correct, however, I would be suspect of how good the terminal to bus connection is if it was operating that loose.

 

[72RoadrunnerGTX]

If you found one of the ammeter terminals loose, may already have some corrosion build up under that stud head internally. As well, make sure the fiber insulator on both sides of the cluster frame hasn’t suffered heat damage. More info here,


https://www.forbbodiesonly.com/moparforum/threads/the-dreaded-“ticking-time-bomb”-factory-ammeter.177831/

 

[kiwigtx]

Ok, from a -40 to 0 to +40 Rally dash ammeter, 0.2 ohms across the copper bus. As noted in previous comments, the resistance at the terminals can vary greatly depending on the quality of the connection of the terminal studs to the bus. The .3 ohms you get after you tightened the terminal is probably correct, however, I would be suspect of how good the terminal to bus connection is if it was operating that loose.

Of course with any measurement of resistance, you first need to establish the resistance of your meter leads, and deduct that from the reading to get the final result.

 

[Don Frelier]

For something like that you need to be on the lowest scale and really scratch into the surface for a clean metal spot.

 

[4mulas]

Just as an update,

I looked at it more thoroughly while laying in my back getting cut in half by the sill plate (lol) and determined that some one had definitely been in there before. The factory one piece rectangular insulator strip on the back side was long gone with just a small piece of it left on the red terminal and a fibre washer on the black wire terminal. So I imagine the original inside insulator was burned, disintegrated and altered to work again at one time too. I did manage to get the studs tight, had low resistance between the terminals and neither were grounded to the cluster itself.

I’m sure it would have probably been fine but I decided to err on the side of caution and just bypass the gauge for now until I find time to pull the cluster and give this the attention to detail it deserves. I also did manage to visit a friend yesterday and left with a good condition, working ammeter, with original insulator pieces intact for $20 ! I’ll put that one in over the winter months when I’m not using the car anyway. I’ll look at servicing/rebuilding the old one at that time...

I do have a volt meter (in the blurry 3 gauges to the right) to help hive ‘some’ indication as to what’s going on for now too...

Hooked up the power and everything works as it should.