How to hook up ammeter?

[Knoxville71shortbed]

I need some help. I'm installing under-dash gauges, and have run into a problem with the ammeter. According to the instructions, it said to remove the wire running from the positive battery post to the junction block on the left inner fender. Then it said to hook one of the wires from the ammeter to the junction box, where I just removed the battery wire. Lastly, it said to attach the other ammeter wire to the wire that was removed from the junction block (which goes to the positive battery post). I did this, and when I attempted to start the truck, it wouldn't crank at all. To double check myself, I hooked everything back as before (disconnecting the ammeter), and the truck started perfectly, as usual. I then tried again to hook up the ammeter (same connections as before), and got the same results (would not crank). What am I missing here? Is there another way to hook up an ammeter? I need some advice here. Thanks.

[JimKshortstep4x4]

My guess is that the amperage passing through the amp meter is too great for the amp meter and it shuts off. It would take a pretty heavy duty amp meter to work with that type of hookup.

The stock amp meters work by measuring resistance over a length
of wire and do not see the amperage directly.

Jim

[Church]

This is how Painless Performance Products reccomends wiring one up for thier wiring harness:

Connecting an Add-On Ammeter and the Maxi-Fuse.

8.1.1 The ammeter must be inserted IN SERIES onto the ENGINE SECTION (single) 10 gauge wire (red) that routes from the fuse panel to the starter solenoid.

The overall physical length of this circuit should be as short as possible (allow some slack, however). You may have to cut wire and you may have to add some additional length of 10 gauge wire. USE ONLY 10-GAUGE WIRE.

Route wire (from the fuse panel) and connect to the ammeter NEGATIVE terminal.

Route the remainder of wire from the ammeter POSITIVE terminal to the starter solenoid battery (B+) terminal. This is the terminal the battery cable is connected to. Splice the maxi-fuse onto the end of wire and connect to the starter solenoid battery (B+) terminal.

CAUTION: BOTH AMMETER TERMINALS MUST ABSOLUTELY BE ISOLATED FROM GROUND. IF EITHER AMMETER TERMINAL COMES IN CONTACT WITH GROUND, A HARNESS FIRE IS INEVITABLE. USE EXTREME CARE AND DILIGENCE IN CONNECTING AMMETERS.

CAUTION: BE SURE YOUR AMMETER'S CURRENT (AMPS) RATING EXCEEDS THE CURRENT OUTPUT OF YOUR ALTERNATOR.

PAINLESS PERFORMANCE DOES NOT RECOMMEND USING ANY AMMETER RATED AT LESS THAN 65 AMPS. DO NOT USE AN AMMETER WITH ANY HIGH-OUTPUT ALTERNATOR (MORE THAN 65 AMPS).

This is for wiring up an ammeter with a painless wiring harness.
Hope this helps,
Ryan

[Knoxville71shortbed]

I'm still confused. From the info Church supplied, it appears that I should break the circuit and insert the ammeter at one of the wires that go to the starter. But it say's that the wire is on the same post that the battery cable is connected to. I don't have any wires connected to the same post as the battery cable. There are two other wires coming from the harness, which connect to two different smaller posts on the starter. Do I use one of these wires as an insert point for the ammeter? If so, which one? Can I make the insert down by the starter, or do I have to cut a wire coming out of the fuse box? I have original fuse box and wiring harness. Surely several of you guys have hooked up aftermarket ammeters on our trucks. I'll take all the help I can get. Thanks again.

[JIMs70GMC]

There's two different types of ammeters, 1 that uses a shunt and an in-line type. The in-line type has the full amperage passing through it. The shunt type measures the mV drop across a shunt that is in-line(full currnet passes through shunt). If the aftermarket shunt you had was the shunt type then it's no good now. If it's an in-line type it could be bad to begin with. What you could do is install it like you did and take a volt meter and verify potential(voltage) on both sides of the ammeter to ground. Should be 12V, this just proves that the ammeter is not opened.

[Church]

See if this helps

http://www.vdona.com/Tech%20Support/...%20Ammeter.pdf

It has a great illustration on the pdf.

[Slammed67]

I'm not trying to steal the show here but how do you go about hooking up the original ameter with a later model internally regulated alternator? All the wires from my fuse block to the front of the truck, so none of the original wiring is there. Where is the "shunt" on the original wiring?

[JIMs70GMC]

The original ammeter uses the red wire that ran along the top of the radiator as the shunt. It was connected between the terminal block on the pass side near battery to the junction of the red wire going to the alt. and external regulator. somewhere near the driver side inner fender.( mine was actually shoved behind the windshield washer fluid bottle.