Oh foccer font of multimeter knowledge

[tommyardin]

Or set the multimetre to 20 volt DC, attach the multimeter (Red wire) to the power supply on the wiper motor, with ignition and wiper switch on and touch the other wire to the chassis of the motor or down to earth on car, if needle or display swings around to show a voltage above 12 volts the the supply is good and the motor is likely to be duff