Join Date: Jul 2007
Location: New Zealand
So if you turn the wipers onto high speed, then back to a lower speed (or off), they don't park themselves, just stopping whereever they happen to be? I think I would start by cleaning the park switch contacts in the wiper motor. I don't know specifically about the 156 wiper motor, but usually on Marelli motors there is a galvanised steel cover that is easy to remove once the motor/linkage is out. The main motor gear usually has a brass track with wiper contacts, or sometimes just a bump on the gear that opens a pair of leaf contacts; clean the excess grease off the contacts, then clean with some metal polish, and see if that brings everything back to life.
Usually I think the total failure of the parking is preceded by a shuddering as the wipers try to park but their current is interrupted by the dodgy contact. I guess if that isn't the case, also check for water damage at the wiper motor plug and clean the contacts with some electrical cleaner.
'00 GTV V6, '08 FIAT 500, shell and parts for a '71 FIAT 850 Coupe