Hi,the alernator on a Massy 35 I recently bought wasn't working I have found out that the problem was the warning light.I bye passed the warning light from the battery plus through an ordinary car bulb to the alternator and it works perfect.I have read of some people putting a resistor on the warning light.The resistance in the warning light is 23 ohms and the car bulb is 1.5 ohms.Can anyone one help with this?
Alternator problem
- Thread starter Dano41
- Start date
Roadworthy
Elite Member
I think your original warning light is defective. Replace it and your problem should disappear. Light bulbs usually read very low on an ohmmeter. The resistance goes up when in use as the filament heats. Twenty three ohms is awfully high for a cold bulb.
def38
Platinum Member
My alternator lamp just opened eliminating the excitation voltage to the alternator with the resulting no alternator output (don't substitute an LED in the circuit. It won't work). I was using a powerful cordless impact wrench in an attempt to remove the steering wheel nut which is severely rusted. The vibration broke the lamp filament. The lamp in my 231S is a 2 watt lamp with a bayonet base. If my calculations are correct, that 2 watt bulb draws about 0.15 amps and has a resistance of about 85 ohms.