Possible Dynamo problems

[PaulHaskey]

Hi 

My S type has just had its radiator re-cored and water pump re-furbished.  It and has come back with the ignition light permanently on, after I start it,  and the battery discharges when i put the lights on.  How can I test the Dynamo, which has the power steering pump on it?

Paul

[piman]

Hello Paul,

have you looked at the dynamo conections in case one has been pulled off when the car was being worked on. Normally the first check is the fan belt tension.
A simple test for a dynamo is to short the field and main terminals together, fan belt off and apply twelve volts to the terminals and body. If it's serviceable it will motor. Observe polarity.

Alec