Ammeter wiring question

[Xavi3r]

Hi, i have a question about the ammeter on my car. I hope the question is not too silly.

The car is : 1970 dodge monaco.

My question is : there are 2 wires at the back of the ammeter. 1 red and 1 black.

Is it normal that the black wiring is grounded ?

I have read the manual and followed the wires and it does not seems that this wire should be grounded but i can be wrong. Can someone explain it ?

-> the red wire goes to the battery via the starter relay and i checke continuity it is good.

-> the black wire ( in blue in the picture) goes to other wires ( horn relay, headlamp relay, acc buss bar, switch column, and to the alternator ) ut it does not seems to me that i should found continuity between the wire and the ground or i am wrong ?

 

[Big_John]

Is it normal that the black wiring is grounded ?

I have read the manual and followed the wires and it does not seems that this wire should be grounded but i can be wrong. Can someone explain it ?

Because the wire is black, that doesn't mean it connects to ground. It just means the color of the wire is black. It's as simple as that.

 

[Ross Wooldridge]

The red wire is the 12V power coming INTO the ammeter gauge.

The black wire is the 12V feed to all other systems in the car. Do NOT ground it!

 

[Xavi3r]

Yes that is why i ask because when i check continuity it is already grounded and that was strange to me. ( more strange is that everyting seems to work fine... )

I know that the color of the wire does not mean anything that is why i checked with a voltmeter and found that i have continuity from this wire to ground. ( on dashboard case, or body for example )

Thanks for you answers i will try to find he problem now.

 

[Ross Wooldridge]

You have continuity to ground because it's coming directly from the battery and running through the amp meter, and when you check for continuity to ground, you are grounding back to the chassis which is connected to the battery...

You won't have continuity to ground on the far side of any of the accessories to which this power from the black wire is being fed to until you turn them on and complete their circuit. When you check for continuity to ground from the black wire after the amp gauge ( before any of the systems or accessories that wire feeds), you are, in effect, completing the circuit.

To the true electricians on the board here, please forgive me as I may not be explaining this very well, or properly.

 

[Xavi3r]

I forgot to mention that i check the wire with dashboard removed. The ammeter is not connected : the red and black wires are not connected to the ammeter, they are connected to nothing.
Sorry but as the wires are a 12v feed they cant be grouned directly.
I can remove every connexion on the black wire circuit, there are only 5 : buss bar, headlight relay, Horn relay, alternator, and steering column. And if i still get ground the circuit is bad.

 

[MoPar~Man]

You have continuity to ground because you have the door open and it's closing the door switch that is wired to interior light bulbs, which have low resistance so you think your positive 12v line is grounded. Remove your interior bulbs and try your measurement again. Also make sure your light switch (head light / dash light) is not turned on. And your key is not in the ignition.

 

[Xavi3r]

Ok thanks a lot everyone i will try that.