1 If the starter motor of Fiat Punto fails to operate when the ignition key Is turned to the appropriate position, the following possible causes may be to blame.
a) The battery is faulty.
b) The electrical connections between the switch, solenoid, battery and starter motor are somewhere failing to pass the necessary current from the battery through the starter of Fiat Punto to earth.
c) The solenoid is faulty.
d) The starter motor is mechanically or electrically defective.
2 To check the battery, switch on the headlights. If they dim after a few seconds, this indicates that the battery is discharged - recharge or renew the battery. If the headlights glow brightly, operate the ignition switch and observe the lights. If they dim, then this Indicates that current is reaching the starter motor, therefore the fault must lie in the starter motor. If the lights continue to glow brightly (and no clicking sound can be heard from the starter motor solenoid), this indicates that there is a fault in the circuit or solenoid - see following paragraphs. If the starter motor turns slowly when operated, but the battery is in good condition, then this indicates that either the starter motor is faulty, or there is considerable resistance somewhere in the circuit.
3 If a fault in the circuit of Fiat Punto is suspected, disconnect the battery leads (including the earth connection to the body), the starter/solenoid wiring and the engine/ transmission earth strap. Thoroughly clean the connections, and reconnect the leads and wiring, then use a voltmeter or test lamp to check that full battery voltage is available at the battery positive lead connection to the solenoid, and that the earth is sound. Smear petroleum jelly around the battery terminals to prevent corrosion - corroded connections are amongst the most frequent causes of electrical system faults.
4 If the battery and all connections are in good condition, check the circuit by disconnecting the wire from the solenoid blade terminal. Connect a voltmeter or test lamp between the wire end and a good earth (such as the battery negative terminal), and check that the wire is live when the ignition switch is turned to the start position. If it is, then the circuit is sound - if not, the circuit wiring can be checked.
5 The solenoid contacts can be checked by connecting a voltmeter or test lamp across the solenoid. When the ignition switch is turned to the start position, there should be a reading or lighted bulb, as applicable. If there is no reading or lighted bulb, the solenoid is faulty and should be renewed.
6 If the circuit and solenoid are proved sound, the fault must lie in the starter motor. In this event, it may be possible to have the starter motor overhauled by a specialist, but check on the cost of spares before proceeding, as it may prove more economical to obtain a new or exchange motor.