lack of sensativity in my ammeter?

[billschroeder5842]

I have a 75 roadrunner with the factory ralley gauges. Everything work except (what appears to be) the ammeter.

The needle does not move no mater what is happening to the car. I'm used to slight movements of the needle when the lights go on, heaters engage or engine revs. This one appears to have no movement at all. I thought I saw it move slightly--like a hair--when I put the lights on.

I have had the system checked and charges at 13.8

I have taken the dash apart and cleaned the terminals-I'm getting current.

Is the gauge defective? Anything I can do to give it more life?

The 75 dash is SUPER easy to take apart--like 8 minutes, so install and remove is no problem.

Any thoughts?

[Ghoste]

That would be my guess.  The guage would have to have current pass through it in order for the car to run but it must be inop at the inidcator somehow.

[Nacho-RT74]

OR you have a perfect and balanced charging system LOL

Note: the ammeters in 75 Mopars changed for a shunted kind ( remote ammeter ), so you can get an inop Ammeter and still get your car working perfect on charging system.

Or it was 76 ?

[b5blue]

  My ALT gauge reads in the + if recharging the battery and in the - if drawing from the battery like when cranking. (70 Charger.) When running and balanced it will only show a reaction bip on the gauge when turning on any device such as wipers, fan or lights. This shows the regulator effecting output to compensate for increased demand. The gauge will not read the total load used, just the state of balance between the battery and alternator.
 With the car not running turn on the headlights or something to run the charge down a bit on the battery and then start the engine. The gauge should read + for a brief time as it recharges the battery.

[Pete in NH]

We had a 72 Dodge Polara in the family back in the mid 70's and it had a shunted ammeter. It was quite insensitive and took quite a current flow to get any reading at all.

[Nacho-RT74]

  My ALT gauge reads in the + if recharging the battery and in the - if drawing from the battery like when cranking. (70 Charger.) When running and balanced it will only show a reaction bip on the gauge when turning on any device such as wipers, fan or lights. This shows the regulator effecting output to compensate for increased demand. The gauge will not read the total load used, just the state of balance between the battery and alternator.
  With the car not running turn on the headlights or something to run the charge down a bit on the battery and then start the engine. The gauge should read + for a brief time as it recharges the battery.

[Nacho-RT74]

We had a 72 Dodge Polara in the family back in the mid 70's and it had a shunted ammeter. It was quite insensitive and took quite a current flow to get any reading at all.

maybe C bodies began before ? dunno.