307 Rear Wiper

[jimmymarsbar]

Rear wiper has never worked as long as I have had the car, and I'm wanting to get it working again. But first, I need to ask a few questions (electrics confuse me to death).

The arm is stuck in the 12 o'clock position, and physically won't move (even by hand).

So, I've checked the electrics. Looking at the wiring, we've got 3 wires - brown, green/yellow and white. I've got 12.5V running across live and earth (brown and green/yellow), and 12.5V between live and the white (is the white a relay switch?). There's nothing between earth and the white. So far, so good, or am I wrong?

Now, I've checked the resistance on the motor terminals. There's a set of 3 pins, and a set of 2 on the motor coil housing.

I get 1.8 ohms when connecting the 2 pins on the coil housing together, and infinite resistance when connecting either of the pins to the coil housing. Again, this seems perfectly normal to me.

Moving on to the set of 3 pins on the arm actuator, I get 2.3 ohms resistance on the central pin and the pin closest to the coil. There's nothing between the central and outermost pin, and between the innermost and outermost.

Is there something that has blown in the arm actuator (resulting in only 1 resistance measurement) resulting in the seized arm?

[RichardW]

Cars, particularly French ones, don't conform to domestic wiring specs, so it doesn't necessarily follow that brown is live and green yellow is earth.... There may also be a timer relay inside the motor unit; but if the car is a multiplexed one; this may be done in the BSI. The wires are probably power, earth and switched power to start the arm moving (once it's going it should park back on the permanent supply using contacts in side the motor). I'll have a look at the wiring diag in Haynes later and see if it sheds any light - but if it's any thing like the one for the Xantia it won't as that showed a dead short to earth any time the arm was moving!! The arm not being able move is probably right as it is likely a worm and wheel drive which you can't force the wrong way (wheel to worm) - however, it is almost certainly seized due to water ingress into the spindle. You might be able to strip it down and free it off, but it would probably be easier to get a used unit and stick it on. I have the rear wiper on all the time when it's wet on mine - the 307 SW does seem to suck water on the rear screen rather effectively!!

[spider]

Richard has beat me to it.

The diagrams are highly likely to stop at where the plug / connector enters the unit itself (in most cases) so you'd not see the 'park microswitch' or suchlike, ie: the very internal parts of the motor itself.

Bear in mind it likely operates intermittently unless someone is holding the 'wash' position on. With that in mind with the multiplug disconnected you should have a 12v feed every few seconds to make it 'sweep'

The 'control relay' is probably inside the BSi I'd expect on these but I'm not 100% sure on that. It seems likely however that it is. My thoughts are the same as Richard in that the motor is probably seized solid however.

This is going to sound obvious (sorry!) but please take care with its removal as it goes through the glass and I do not think toughened glass will tolerate much 'bending' around the motor aperture area.

[jimmymarsbar]

Cheers chaps, the only observation following from your comments is that there isn't the intermittent 12V coming from the wiring loom, just a steady 12V on the brown and white with earth. So I'm assuming the timer relay is in the motor itself.

I'm not going to attempt to dismantle it until I find the spec for the rivets for reassembly, they're big buggers!

[spider]

From memory there should ( ! ) be an intermittent 12v feed, as in a second or two's "power" then nothing for about 5 to 10 seconds, then this repeats. This is just with the wiper on. With an assistant holding the stalk in the 'rear wash' position, there should be a permanent 12v supply.

On a 306 the 'timer' is in the rear hatch itself but on the 307 (I'm about 90% sure so I could be wrong) its not. The 'time' is in the BSi or fusebox.

Hope that makes sense.

EDIT... One test you could do is compare the power / feeds on each wire with it held in the wash position.

[RichardW]

I did look at the diagram.... it's not very clear! Control is via the BSI. Of the 3 wires, one is def earth, and this is probably the green / yellow one, and should be on pin 3 of the plug. Pin 1 of the plug can be either earth or power, depending on the state of a relay in the BSI - I suspect that BSI temporarily earths this wire to start the wiper, or allow it to run on after washing (on mine there are 3 wipes after wash goes off). The wire to pin 2 shows as coming from the electronic brain, but I suspect this is perm 12V. Some internal switching in the motor is shown, but this looks to be only to do with providing the earth for park function. You can probably just drill out the rivets and replace with bolts. However, there are quite a few on ebay around the £20 mark, so I wouldn't try too hard with it!

[jimmymarsbar]

I picked up a second hand motor from a breakers, that too isn't working, so I've been unfortunate in picking up another duff motor, or the issue lays elsewhere.....

[spider]

This sounds obvious I know but you have double checked all the relevant fuses ?