2 speed wipers

[MikeyB1]

Sorry to be a pain everyone.  I've read all the posts I can find on this topic, including those of the wiper "guru" AlanT.  I've stripped down a spare DR3A motor, and identified (I think) the field coil wires. Referring to the photo, are the field coil connections the 2 in the middle?  One has the parking(red) wire attached, the other is just to the right.  AlanT suggests fitting a resistor into this circuit to enable the second speed.  Do I solder the resistor across the ends of these wires, or do I cut just one wire, solder it to a flying lead fom the resistor, and from the other end of the resistor, take another lead to the remaining field coil connection?  To prevent me getting confused, could some kind person draw me a simple diagram?  Thanks folks, Mike.

[tthomson]

It's not as simple as adding the resistor across existing connections.

Your picture shows the field coil and brush holders, but does not show the wire that connects to the outside world. On a single speed motor, there should be a Green/Red wire soldered to the end of the coil that is also connected to the Red park wire.

The first requirement is to disconnect the end of the coil that is connected to the park wire. (shown with a sleeve in your photo). Label this disconnected wire (I)

Remove the Green/Red wire that is normally soldered to the connector with the Red park wire (from which the coil connection has now been disconnected)

To convert to a twin speed DR3A motor this Green Red wire will need to be replaced with a Green/Brown wire soldered there instead. (do not reconnect the loose coil connection) Label this Green/Brown connection (II).

Once a suitable location for the resistor is found, it will need to have wires soldered to it. One end will need a single wire that connects to the junction of the red park wire and Green/Brown wire as mentioned above (II). The other end of the resistor needs two wires, one is the Green/Red wire recently removed, and the other is used to connect to to the disconnected coil ending (I).

Since this connection is likely to be very delicate, you need a way to fix this within the motor so that it is robust enough while not getting caught up in the motor mechanism. A spot of a fast acting two pack epoxy adhesive will suffice to fix the wire to the plastic former, (Two closely spaced 1mm holes can be used used to hold a loop of this delicate wire in place ready for soldering. (note that this wire is coated in an enamel that need to be carefully removed so that a soldered joint can be achieved.)

The wiring is then complete, but the operation must be correct or you will cook the motor.

In Slow mode, both Green/Red and Green/Brown wires MUST be connected to ground via the switch (i.e. both ends of the resistor)

In fast mode only the Green/Brown wire is connected to ground via the switch. (i.e. the Park wire end of the resistor)

 

Good luck with it

 

TT

 

 

Edited October 9, 2020 by tthomson

[MikeyB1]

Thanks TT, looks like I'm going to have to do a little more work than I thought.  Mike.

[MikeyB1]

TT, I'm confused now. There is no Green/red wire in or on this motor. The only internal wiring is as you can see in my photo. the connections to the outside of the case are the two tags seen at the top of the picture which protude through the end cap. There are 3 leads going to the motor, 2 for power and a separate one for the earth. The red lead seen soldered to one side of the coil exits the case and is connected to the parking connection. The motor ran before I stripped it down so there cannot be any missing wires, surely.  Hopefully you can see my confusion, any comments?  Thanks, Mike.

[RogerH]

Hi Mikey,

the single speed motor has Green (+12V)  Black earth  and a Green/Black switch earth to turn it on.

To get it to two speeds you need to put a resistor in series with the field but it needs to be switched so that no resistor gives slow speed and

with the resistor the a faster speed (but lower torque)

 

Roger 

[MikeyB1]

Thanks Roger,  gradually getting my head around this.  Got to cobble together some temporary circuitry now to check whether or not I've got it right.  Mike.

[RogerH]

Have you done a search here for all the relevant posts that AlanT has submitted. Lots of good info.

 

Roger

[tthomson]

On 10/12/2020 at 8:38 PM, MikeyB1 said:

TT, I'm confused now. There is no Green/red wire in or on this motor. The only internal wiring is as you can see in my photo. the connections to the outside of the case are the two tags seen at the top of the picture which protude through the end cap. There are 3 leads going to the motor, 2 for power and a separate one for the earth. The red lead seen soldered to one side of the coil exits the case and is connected to the parking connection. The motor ran before I stripped it down so there cannot be any missing wires, surely.  Hopefully you can see my confusion, any comments?  Thanks, Mike.

Hi Mike,

As RogerH states, there are Lucar spade connectors on the single speed DR3A, and these provide the connections to the outside world.

On Two speed versions, the wires were soldered and there were three fly leads that exited the motor. These were Green supply, Red/Green, and Brown/Green.

On my TR4A, I had a loom upgrade and this included wiring for a twin speed DR3A. Since it was running with a single speed DR3A, The Red/Green wire was used for the motor  switched earth connection.

Apologies for any confusion. I have attached a diagram that may help. I think the wiring of the switch is correct, but check before using. In slow mode both resistor ends must be connected to ground.

Tony T

[MikeyB1]

That's great Tony, exactly what I wanted.  I'll print it off and go and play in the garage.  I'm going to use an old motor first before I take apart the one in the car.  Thanks again, Mike.