Big favour for my stupid rear wiper!

[Deefadog]

Cheers, at least now i nopw what i should be checking

Should the voltage be a constant 12V?

[Organisys]

Should be a constant value yes, may not be exactly 12v for various reasons, but should stay around the same figure.

pull and tug at the connectors and wires, especially the earth and at the 'bellows' between car and tailgate.

[Deefadog]

ok, thanks!

[KKK]

There are three wires routed through the tailgate to the rear wiper motor:  earth, 'park' (constant live) and 'activation' (controlled by the relay).  If you take the motor apart you'll find an 'activation' track, and a 'park' track.

When you switch the rear wiper on, the 'activation' track goes live.  This moves the wiper enough to contact the 'park' track.  This makes a single sweep happen, and parks the wiper.

The relay then goes 'activation' live after a few seconds, setting off another sweep.

If the 'park' wire is broken (very common on '80s VWs with tailgates), the 'activation' part of the cycle gets the wiper moving.  When the relay cuts the current, the wiper stops.  Next time the relay kicks in, it powers round another part of the rear wiper cycle before stopping. And so on...

You need to solder a new section of wire into the loom passing through the tailgate to fix it properly.  If you plan on keeping the car for a while, replace all three wires (they all go eventually, but the 'park' wire seems to go first, maybe because it's live all the time).

KKK

[Deefadog]

Fantastic, well that sounds like what is wrong!

I'll pull the wires through tomorrow and get them sorted!, i'll temporary bypass the wires out side of the tailgate first to make sure it right!

cheers mate your a star!

[Deefadog]

KKK  - Just got the multi meter on the wires! The green/black wire has 7.14V on ignition and rises to 11.46ish on the relay click!

Brown - does nothing

Black/grey - also does nothing

Before i strip the wiring does this sound like it's the wiring? should i get power through one of the other wires?

Thanks

[KKK]

Just pull back the grommet where the tailgate meets the body.  It should be clear enough if one of the wires has broken.  You could also do a continuity test between the plugs behind the LH rear light cluster, and the plug that feeds the rear wiper motor.

KKK

[Deefadog]

I have pulled back the grommet, no signs of any wear at all!

"continuity test between the plugs behind the LH rear light cluster, and the plug that feeds the rear wiper motor"

Not sure what you mean, can you explain a bit more - really thick at this sort of thing, sorry!

[KKK]

The other end of the wiper motor plug runs to a couple of plugs just behind the rear light cluster (pull back the carpet).  Give the wires under the grommet a tug and you should see where the connection is.

KKK

[takethefifth]

And apologies for the upside down pic! I had the boot open looking up at the time...