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Sierra Wiper - Blowing Fuse


Chris Scott

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Hi all, this is a bit complicated to explain but here goes…

I have a Sierra wiper motor, but doing away with Sierra column switches.

When I switch ignition on the wiper motor makes a grinding noise and blows it’s fuse.

If I wire directly to battery the motor is fine.

My question is, if I want just a simple on/off for wiper motor how do I wire it?
 

As loom has 5 wires and the feed from fuse is a permanent live…I assume the old column switch did some magic as you normally select a speed.

 

03E1DB18-60FE-4445-A1A7-975662419A80.jpeg

5FB4789E-0EDA-4E07-9A97-5A35364727F7.jpeg

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I am part way through wiring up my Sierra wiper motor, but have not finished yet due to other distractions, however I can share my plan if it helps. Firstly I include a snippet from the wiring diagram as fitted by Ford.

Sierra-Wiper-Motor-Connections.jpg.d46b20ddea85e7fe66741f84f128e0b2.jpgThis shows the original wire colours (Sw = black, German I think) The important thing is that as the motor turns it operates a switch that connects 31B to either 31 (parked) or 53A (not parked) I worked this out by monitoring the switch connections when the motor was turning. By the way avaoid trying to power the motor by connecting 53B and 53 to the battery, the motor runs very fast, too fast like this and would burn out.

I now include my planned circuit, using two independent 2 pole switches to allow wiper self parking and two speed operation.

Sierra-Wiper-Sketch.thumb.jpg.757a72582a2e9e7beb5bce5ca57da354.jpg

 

The numbers on the connection block are in the same order as shown on your photo. Note I believe that connector 31 is earthed within the motor assembly so you must not wire any power directly to 31B because if you do a short circuit will occur when the motor arrives at the park position and the fuse will blow. This might be what is happening in your current wire setup. In the above the wipers operate via two switches, a "master switch" turns the wipers on or off which a second switch selects the speed. When the wipers are turned off and not already parked power from the Off pole on the switch is routed through the Park Position switch to turn the motor until it reaches the park position, and there disconnect.  I repeat that I have not yet built this circuit, it's just what I plan to do if I get problems with the column switch and delay relay etc in the fuse box.

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1 hour ago, Sparepart said:

I am part way through wiring up my Sierra wiper motor, but have not finished yet due to other distractions, however I can share my plan if it helps. Firstly I include a snippet from the wiring diagram as fitted by Ford.

Sierra-Wiper-Motor-Connections.jpg.d46b20ddea85e7fe66741f84f128e0b2.jpgThis shows the original wire colours (Sw = black, German I think) The important thing is that as the motor turns it operates a switch that connects 31B to either 31 (parked) or 53A (not parked) I worked this out by monitoring the switch connections when the motor was turning. By the way avaoid trying to power the motor by connecting 53B and 53 to the battery, the motor runs very fast, too fast like this and would burn out.

I now include my planned circuit, using two independent 2 pole switches to allow wiper self parking and two speed operation.

Sierra-Wiper-Sketch.thumb.jpg.757a72582a2e9e7beb5bce5ca57da354.jpg

 

The numbers on the connection block are in the same order as shown on your photo. Note I believe that connector 31 is earthed within the motor assembly so you must not wire any power directly to 31B because if you do a short circuit will occur when the motor arrives at the park position and the fuse will blow. This might be what is happening in your current wire setup. In the above the wipers operate via two switches, a "master switch" turns the wipers on or off which a second switch selects the speed. When the wipers are turned off and not already parked power from the Off pole on the switch is routed through the Park Position switch to turn the motor until it reaches the park position, and there disconnect.  I repeat that I have not yet built this circuit, it's just what I plan to do if I get problems with the column switch and delay relay etc in the fuse box.

This is really helpful thanks, but my limited knowledge of electrics still sees me stuck…but hope you can help…

If I wanted to run a simple on/off switch to make this work on (let’s say) fast setting only - would I just need a switch between the feed from the ignition and the 53B terminal? 
 
Am I right in assuming the motor earths through the body and not any of the terminals?

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Yes a simple switch from a suitably fused power source to 53 or 53B will give normal or fast motor speed. In it's original mounting in the Sierra the wiper motor and mechanism is fixed via rubber bushes to absorb vibrations, so if you have retained these the outside case of the motor will not be earthed. The contact 31 needs to be connected to an earth point. That would be the black wire in the wire list you posted at the start of this thread. Obviously if you use a simple switch the wipers will stop wherever they are turned off.

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11 hours ago, Sparepart said:

Yes a simple switch from a suitably fused power source to 53 or 53B will give normal or fast motor speed. In it's original mounting in the Sierra the wiper motor and mechanism is fixed via rubber bushes to absorb vibrations, so if you have retained these the outside case of the motor will not be earthed. The contact 31 needs to be connected to an earth point. That would be the black wire in the wire list you posted at the start of this thread. Obviously if you use a simple switch the wipers will stop wherever they are turned off.

Absolutely ace, thanks! I will use your diagram to have one final bash as I may have wired it wrong! But if not I’ll do the simple circuit described above 👍🏼

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Actualy you are better off trying the simple swiitch setup. On close examination I can see a flaw in the more complicated circuit I proposed above. You can see that when the wipers are parked 31B is could be earthed. I show a connection from 31B to the ON pole of the first switch. This means that if 31B is earthed and the first switch is moved to the ON position a short circuit will occur and blow the fuse. This will not be a problem with the simple switch to power either 53 or 53B directly. I need to get back into the garage with my test leads. 

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Okay, I have had a good poke around with the meter probes, and can confirm that connector 31 (leftmost in the photo) is connected to the motor body and the whole wiper mechanism. So the motor won't run without the body being earthed which means connecting connector 31 to earth. This means the my brilliant circuit diagram above is useless because it will cause the fuse to blow when the wipers are turned on from the park position. So I have given the matter more thought and have come up with a circuit that should work, using a relay. It still uses the two two pole switches, however could easily be modified to use a 3 position switch, where each position would give a connection. Anyway I have inserted the suggested circuit below. I realise you don't intend to use it, but I just couldn't leave this thread with a duff circuit diagram.

Sierra-Wiper-Sketch-s.thumb.jpg.518d37e21fcd57d9acd689a07373e33e.jpg

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On 7/16/2022 at 3:29 PM, Sparepart said:

Okay, I have had a good poke around with the meter probes, and can confirm that connector 31 (leftmost in the photo) is connected to the motor body and the whole wiper mechanism. So the motor won't run without the body being earthed which means connecting connector 31 to earth. This means the my brilliant circuit diagram above is useless because it will cause the fuse to blow when the wipers are turned on from the park position. So I have given the matter more thought and have come up with a circuit that should work, using a relay. It still uses the two two pole switches, however could easily be modified to use a 3 position switch, where each position would give a connection. Anyway I have inserted the suggested circuit below. I realise you don't intend to use it, but I just couldn't leave this thread with a duff circuit diagram.

Sierra-Wiper-Sketch-s.thumb.jpg.518d37e21fcd57d9acd689a07373e33e.jpg

Sorry for the late reply, this was so helpful!!! 
 

Now have a fully functioning wiper circuit 👍🏼👍🏼👍🏼

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