Borrowed a friends ammeter since I didn't have correct one for '26-'27 instrument panel & it worked as it should - needle moved to "CHARGE" side of gauge when the engine was running. Installed Model A ammeter (catalogs say they are the same) and it reads "0" at idle & "DISCHARGE" when I give it throttle. I tried switching wires, but no change. Is it possible the ammeter is defective or do I need to check something else? Haven't changed anything with the wiring since I changed out the ammeter.
Would appreciate any help from my distinguished Model T colleagues!
Maybe they're not the same? Don't forget Model A's are built on a Positive ground system, maybe that makes a difference? Heck if I know but thought I'd throw that out at ya. And maybe it is defective.
Just switch the wires around on the ammeter.
I switched the wires on the back of the gauge - no change; still reading "DISCHARGE" when engine is running.
I just saw the last portion of the post. Hmmm? I have a an early Model A ammeter and it reads fine. Might want to hook up an older model ammeter to the system and see if it works OK first. Then determine if the issue is something other than the ammeter. If not, time to find another ammeter.
Measure the voltage at the cutout, first with the engine not running and then with the engine running fast enough to close the cutout.
If the voltages are the same, your generator is not working or the cutout is not working.
If the voltages are 1.5 to 2 volts higher, your ammeter is defective.
A quick jumper around the cutout with the engine running fast should be enough to polarize your generator field windings and initiate a charge cycle.
Jumpering a cutout is OK but if he has a VR on there and doesn't know it then you will damage the VR by jumpering across it. If in doubt - don't jumper across the "cutout" - it might be a VR.