Wednesday, December 30, 2015

Fiat Panda windscreen wiper timer

My Panda, after almost 16 years of service, begins to show its years.
This time, the front  wiper does not work properly.
You may read almost evreywhere, Google is your friend....
About this matter, it seems nobody ever went deeper, and to my issue, which seems to be quite widespread, Google wouldn't helped that much; the only answer I found by it is "change the motor and its controlling circuit". This solution can be quite expansive, looking around for prices,  it seems you can not find it for less than 100€.
On the other hand, looking at the controlling circuit, it does not seem to be very complicated, so I decided to use some time to resolve my issue, and therefore save 100€.

As from the image I included in this post, circuit itself is not too complicated.
I also made some schemas to help myself in understanding its behaviour.

The switch appearing in the bottom of the schema, is embedded in the gear inside the transmission of the motor. Its rotation make the controller understand about the wiper position. It is a plastic gear with the core made of conductor material. It appears as follow:
Where the RED part is the metallic core, and the black lines is where contact from the control circuit goes.

Well, I guess this is the time where I tell you which is my problem, after all.
Problem is as follow:  the "SLOW" speed of the wipers does not work, and when it is set to the "FAST" speed, if you turn off the wiper it stops where it is, without return to its home postion.
After several hours of analysis, I found where the problem lies.
It is due to the oxidation of the normally open contact of the relay.

This way I saved myself more than 100€ for the spare part, I hope anyone else could found my info useful and save his money.

1 comment:

  1. Warning: manual tests of the normally open contact of the relay, may lead you to wrong conclusions. During my tests, I tried many times the contacts conduction placing the normally open contact in conduction state manually. The force you apply to the contact using your finger is more than the magnet normally applies, in this condition, oxidation that prevents current to flow when the contact is automatically switched on, and the current manages to flow, giving you the impression that the relay is working properly. In my case this fact ate most of the time, leading me search the issue elsewhere.