twiss wrote:I'd think you would either just earth it to some bodywork... or straight to the battery
Never earth an ameter!!!!!!!!!!!!!!!!!!!!!!!!!! A ammeter is designed to go in serise to measure the amps in a circuit
Looking at the amp guage you have there it seems that it is going to show whether the battery is charging or discharging
Disconnect your + terminal on the battery the SJ should have two wires connected to it as standard, one is a big brown or black cable that goes to the starter motor, The other is slightly smaller but not as small as the other wires in the car its should have a short thinner wire connected to it (this is suzuki's idea of a fusable link) the link joins to another fatter wire which should be white with a yellow stripe.
Disconect the link nearest the battery and connect a 6mm squ UK equivelant of 10 AWG (American Wire guage) this is chunky stuff (remember you have all the SJ's electrics apart from the starter circut running through this cable) Use tri rated cable as its flexible and resistant to heat, oil etc
http://www.electriccableco.com/electric-cable-shop.htm this is a very good shop and will sell you cable by the meter use red or white to indicate a positive feed.
Firstly connect a inline fuse of 45amp remember the holder must be also rated to this or higher. Run you cable into the car connect to one of the meters terminals. It doesn't matter which one as the meter will work backward if wrong just swap the terminals around.
From the other meter terminal run back out into the engine bay and reconnect onto the fuseable link.
If done right this is what should happen
Ign on slight neg amps turn on more things the amp meter should show more neg
Start the engine meter should swing over to loads of neg amps
When running the meter should show a slightly positive amps
A few things to note
Cable terminations must be very good use a proper cable crimper to fit crimps, I.e not pliers or those sh.1.t squash together things.
Because you are dealing with reasonable high amps a poor termination will become warm/hot and inside your dash can then melt the surounding cables etc nice mess
When running the cables through the engine bulkhead ensure that they won't get damaged. If one of these cable gets cut to is core it will be like directly shorting your battery out with a screwdriver Which brings me back to my original sentance don't earth out a ammeter.
Hope this help I can do a pic if required