Amp light help.

49 Hudson with 53 308. When I first started driving the car the light would come on at idle. I was assured that it was normal for it to come on when at low speed due to the generator. Now out of nowhere the light is on and stays on. Sometimes if you rev it up really high it will go out but not all the time. I've checked the volts at idle and it's over 6 volts. 6.35, something like that. What I'm trying to determine is if I have a generator issue or a light issue. Where to look next.

 

might be voltage regulator if not gen.

 

Sounds like worn OR dirty gen brushes, comutater will need to be cleaned, scribed, and brushes replaced.

Hold it! You're not done yet...Now check the voltage regulator. (too many years since I did this one, Hudson used a different wiring mode than Ford and GM...)

Motor's repair manual will have the procedure. Follow it to the letter...or burn the points.

Let me go look in my Motor's manual...Be back further down the thread.

 

O.K., once you are ready to check the regulator, first make sure the regulator is grounded. (loosen the screw at the ground wire and clean the connection! Resistance at the ground is as important as in the power source.) A jump wire can be used to temporarily ground the regulator body to an engine ground.

If the light still comes on, connect an ammeter in series with the 'Bat' terminal and the battery. Run engine at high idle, (1200-2000 RPM)

Now ground the 'F' (Field) terminal of the regulator, with a 'jump wire'. Ammeter should show a good 10-15 amps charge, if not:

Disconnect grounding wire, and temporarily connect the 'Arm' (Armature) terminal to 'Bat' terminal on regulator. This shorts out the circuit breaker, and should show full charge, again 10-15 amps.
If it doesn't provide full amp charge the regulator is bad.

A good Automotive Electric shop can adjust the regulator if it charges when tested, but doesn't in the car.
But with the dimly glowing lamp, my guess is bad ground or dirty/worn brushes.

 

If I can add a caveat...Mike is not talking about the built-in ammeter on that $16.95 multimeter you can get at AutoZone...unless you want to smell smoke.

 

Exactly right, sorry for the oversight! You'll need a GOOD ammeter, (actually an old Stewart-Warner, or generic...Pep Boys carries the Sunpro line, which is a re-creation of the old Sun Electrics.

Thanks, Adj Johnsns...

 

Thanks for the info I will start digging on it today.

 

Good, as in 0-40 amps AT LEAST. Most generators will put out 30 amps, some more. Your ammeter must read over the spec for the generator.

Motor manual is a must.

Cosmo

 

Check the belt to see if it's slipping.