I decided to install new gauges in my 66 mustang (as you can probably guess the original ones did not work).

It came time to install the ammeter and for the life of me I can't figure out the "best" way to install it.

I have searched again and again on google and this forum for answers but haven't found a definitive answer.

I know that it will need to be wired in series and have attached a diagram to show what my brain thinks is the right idea. My issue with this is that I would need to run 10gauge wire from the solenoid to the cluster and back to the alternator.



This second schematic is one I found while searching and from what I have read it seems that this wiring will only work for the original ammeter.



Any advice you can offer is appreciated.


Thanks
Scott

Some of you will probably tell me to use a Voltmeter. I already have a voltmeter but want an ammeter too.

 

I had an ammeter in my car for a short time and switched to a volt meter for simplicity. I don't see the need for both?

 

The original 66-73 ammeter actually does work. IF you clean the daylights out of every connector between the gauge and the alternator, and lightly grease them with dialectric grease. Then they'll go full travel.

 

I retrofitted both an ammeter and voltmeter so I figure I should get them both working - I will give that a shot 2+2GT, thanks.

Also please disregard the top diagram, upon actually looking in the engine bay I can now see it's quite inaccurate.

 

a) the ammeter should be wired up the very same way as the original was? I don't see why that should be different.
b) if all the gauges were not working thenit usually is related to voltage regulator or similar. however the ammeter doesn't use this so I'm with 2+2 on this one. Give the original another shot. Especially the firewall connectors migh need cleaning.

 

The problem with the first diagram circuit is that all the alt current goes thru the ammeter before going into the battery and depending on the alternators output, finding the correctly rated ammeter may be hard to do (30-110 amps load + 40% increase for safety margin). Not to mention the addition of a single point failure of the device or wiring/connections. As shown in the second schematic, the factory uses a "shunt" type design to allow the alternator's current to go directly back to the battery while measuring the voltage drop/increase across the battery charging circuit wiring and is frankly a little safer from a failure perspective. As already discussed, cleaning the connections, and ensuring you have a good gauge are sound advice and should put you back in business.