Technical Rear wipper motor issue

Currently reading:
Technical Rear wipper motor issue

shiftyone

New member
Joined
Aug 2, 2017
Messages
2
Points
1
Hi all,

I'm new here and like most my first post is because of a problem on my punto evo :(

Recently my rear wiper started to worked intermittently when turned on. I guessed a faulty contact on the plug and I was right. The black wire (earth?) has been cut, no idea how.

So I tried to fix it with what I had at my disposal, that is some electrical wire. I attached some to the remaining metal bit of the black wire and made sure the electrical wire would go through the plug. I also made sure it wouldn't touch any of the 2 other wires.

Now the rear wiper works anew BUT the cycle of wiping: wipe > wait few seconds > wipe again > etc., isn't happening any more.

When I turn it on it either constantly wipes until I turn it off. Or wipes 3 times and stops in the middle of the 4th time and never turns on again.

Is it possible that my home-made fix on the black wire is causing the wiping cycle not to happen?

Thanks for your help (y)
 
Last edited:
The wiper motor is working .. but from your comments it seems as though you may still have a wiring/earth issue somewhere.

This is actually a common fault across all marques of car. The rear wiper isn't used as much as the windscreen wipers and tends to 'deteriorate' - bad earth/corrosion - because of this.

The other cause of such problems is the opening and closing of a tailgate. This actually causes wires to become brittle where they pass through rubber grommets/flex and can lead to breakage. The strands of the wires break and cause all sorts of intermittent problems.

It's more than likely you have a wiring fault somewhere. If you don't have a voltmeter, an auto electrician will charge about £25 and take just a few minutes to find the fault
 
Re: Rear wiper motor issue

Hey Glenn,

Thanks for your reply.

I can easily get a voltmeter. Where should I try to measure? I guess after the tailgate but where can I easily access the wire before the tailgate?

In the eventuality that the problem comes from the wire, how do I fix this? :confused:

Thanks :)
 
Re: Rear wiper motor issue

Start with what you already know - the earth wire. You'll have to remove trim/panels to get at the wiper motor. If need be, try putting an extra earth wire from the motor to anywhere you can fit the other end - such as underneath a nut. It may be that despite your fix you still have a 'bad earth'.

Try loosening and retightening the mounting/holding nuts. That can often cure a bad earth. It's likely that your earth wire actually broke due to the constant opening and closing/vibration of the tailgate. Think of a metal coat hanger - you can bend it in the same place a number of times before it eventually breaks.

Use the correct thickness of wire - an independent car accessory shop should sell it. It's not a good idea to 'twist' 2 pieces of wire together and bind them with tape. Use proper terminals/bullet connectors.

If by electrical wire you mean household appliance wire, well, differing thicknesses of wire have different resistances.

If you sort the earth out and you still have the same problem, then check the current feed. You do that by disconnecting the supply wires from the motor and putting the voltmeter between the wire between the disconnected wire and where it would connect on the motor. Get somebody to operate the switch for you ..

Be aware, however, that a broken wire strands (broken inside the plastic casing) can cause an intermittent fault .. work .. not work .. work .. The usual location of this fault is where the wires come through a rubber grommet from the car itself and go into the tailgate. You'll see them as soon as you open the tailgate.

An auto electrician would also test the resistance of the wire - broken strands alter the resistance. They do that by inserting a 'spike' on the end of a wire through the plastic casing of the wire and the other end is connected to the wiper motor.

For most home mechanics whose eyes would glaze over at the mention of resistance/ohms .. it just means broken strands in a wire. It's the 'coat hanger' effect - you hold and continually bend a coat hanger and eventually it snaps on the bend.

On a tailgate the bend is where the wires come through the rubber grommets between body and tailgate.

If you can identify which wire has broken/broken strands (if any..) you don't just cut the wire and 'twist them together with tape'. You need to insert a length of new wire - with bullet connectors. Constant opening and closing of the tailgate causes the wires to 'pull'.

About a year ago a friend of mine had the problem of a non-working rear wiper on his old Volvo estate. A workshop diagnosed a burnt out rear wiper motor. A new rear wiper motor excluding labour set him back £275. Of course it didn't fix the problem ...

.. and he went to an auto electrician almost directly opposite my house .. and bingo ..10 minutes later the auto electrician had diagnosed a wiring fault (broken strands..) in the loom that goes from the car to the tailgate..

It's rare that the main windscreen wiper motor fails, to be honest. The rear one is used even less. Most of the rear wiper problems come down to bad earth/broken wiring because of the opening/closing/ slamming of the tailgate.

I have an 01 4 litre Jeep. Low mileage. If I need to use the rear wiper I go to the back of the vehicle and slap the tailgate to get the wiper going. I don't have the slightest intention of looking for the problem .. which is probably a 'bad earth' or corrosion around the mechanism.

You can fix your Fiat yourself. Get the correct auto wiring and connectors, but do look at the earthing first.

You would access the wiring just before it enters the tailgate - before the 'bend' and just after the 'bend'

Keep us updated..
 
Last edited:
Back
Top