amp dashboard light not illuminating

T

tsanborn

Member
I've replaced the generator in my '56 Country Sedan with an alternator and rewired the car with a Painless harness. Everything is working except I'm not getting the amp light to illuminate when the ignition is on but not running. There is power passing through the bulb to the white exciter wire that plugs into the alternator. It is a GM style 10SI with a red and a white wire plug. If I pull the plug out and short it to ground, it illuminates. Any thoughts? I've asked Painless and they were not a lot of help.
 
The old generator lights were turned off by the cut out in the voltage regulator back in 1956. The modern set up for alternators is different since it's controlled by the alternator VR circuit but it can be made to work. There should be info on this site and on U-tube about these modifications.
 
It is a GM style 10SI with a red and a white wire plug. If I pull the plug out and short it to ground, it illuminates.
Click to expand...

I will never understand why one would use a DELCO ALT on a FORD, especially a ONE-WIRE. No one tells you all that has to be done to make it functional. The ONE-WIRE was released for farm and off-road equipment.

After all of the dust (and sparks) settle, it still has to be wired as a three-wire.
 
The 10si is normally a three wire alternator with the other two wires of the little plastic plug being for that alternator out warning light circuit and for immediate alternator excitement. The cars that used the 10si had a diode in the circuit to prevent reverse current flow. A person has to look at the GM vehicle wiring diagrams for a vehicle with the 10si to see how it works. This way a person doesn't have to rev the car up to get the alternator to excite. There is likely a circuit diagram on line somewhere if a person googles it.
 
Ford has "one wire" alternators, 2G and 3G. Getting either from the correct late model only requires a pulley change (original 1G pullet is a direct swap) and a single exciter feed from the run side of the ignition switch through a light bulb. Put a 2G in my 36 and a 3G in the Ranchero. Yes it does require an output feed to the battery.

When I return from vacation I will post the sourcing info if interested.
 
The 2G update is readily available on both Amazon and epay.....87 Aerostar 3.0 for the 2G

95 Mustang 5.0 for the 3G....both are bolt in replacing the old 1G.

Homemade mounts but nice fit on a 351C where the 1G would have been..
 

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