View Full Version : Wiper motor (two speed) connection

11-16-2006, 10:40 AM
I am trying to trouble shoot the wiper motor on my TR4A. It seems to be a two speed motor with three wires (plus ground) going into it. However the wire diagram I have for the car seems to show a one speed motor with a simple SPST switch.

From my experimenting it seems the motor works on slow when both inputs are grounded and then on fast when only one input is grounded. My switch does have two on positions and five terminals. I may have a TR250 or TR6 wiper motor and switch for all I know.

Does anyone have access to a wire diagram that shows the two speed motor set up (or can describe it in words). I am trying to ring out the switch to figure out where the wires go. I assume one switch terminal goes to ground and two others go to the motor (the third motor input seems to be hot all the time which makes sense if the switch grounds the other side). But not knowing if the switch is working properly ringing out the switch does not tell me much (I need to know what the switch is suppose to be doing /ubbthreads/images/graemlins/smile.gif

Don Elliott
11-16-2006, 12:29 PM
Adrio - My TR3A has a 2-speed wiper motor.


11-16-2006, 12:49 PM
This article (https://www.vtr.org/maintain/wiper-problem.shtml) by Dan Masters should help you out. /ubbthreads/images/graemlins/driving.gif

11-16-2006, 04:19 PM
Thanks Matrix-5. I took a look at that article and it seems my wiper motor is not like either of those. Mine is like the "earlier models" described only there are three wires and not two as the article shows (fair enough as the article only talks about a one speed earlier model). My model only has two brushes not the three as shown in the diagram for the newer models.
Thanks for the help so far folks.
Does anyone know of a repository of wire diagrams for TR models. Maybe there is an intermidiate diagram for what I am looking for (maybe a late TR4A or early TR6 something like that, sort of like the electric temp gauge that looked like the either bulb one before they went to the "new" TR4 temp gauge face).

11-16-2006, 05:08 PM
Again, Dan Masters has all the TR schematics at his site https://www.advanceautowire.com/ Just click onto the "Stock Schematics" on the left side. Nicely laid out and color coded.


11-16-2006, 10:05 PM
/ubbthreads/images/graemlins/driving.gif I'm not going to be of much help other then you have a Tr250 2 speed wiper motor. So when you look at the Dan Masters diagram look under Tr250. However I've been there and it does not show the correct 5 post switch that we have. It shows the TR6 3 post switch. I have a problem with my 250 wiper motor too so I'll be watching. You are correct that the switch sends the current to ground to start the motor. The switch is serviceable too. The back comes off and you can clean the contacts. Carefully observe how it comes apart. I also believe the reason the lead wire is hot is to send the wipers to the rest position after the main switch is turned off.

11-17-2006, 10:14 AM
On the TR250 wiper motor, there is a trick to getting the "slow" speed to operate. You have to energize two of the field wires comming out of the motor.

That is, you have one lead into the motor that is always energized (necessary to allow the motor to "park"), an earth wire, and the two field wires. The "hooters" switch that is original to the TR250 energizes one of the two wires to get "fast" and two to get "slow". If you are using a replacement TR6 switch it will only energize one of the field windings at a time. To modify the TR6 switch to work with the TR250 motor, you need to install a power diode across the two connections to the field winding. This should give you the correct effect.

All the colours are worn off my wiper motor leads so I cannot tell you which to connect where. I had to sort this out by trial-and-error, and would suggest you try the same.

Anyway hope that helps.


11-17-2006, 01:14 PM
Thanks Rob and TR3ATR250. That is what I needed to know. When I got my motor working the operation was as described by Rob. I wanted to make sure it was to fields for slow mode. And since TR3ATR250 told me I can service the switch I was able to fix that as well.

My problem in solving this was I had more variables then equations. Thanks to the forum I was able to get the required number of equations.

For those watching who have problems with the motor, what was wrong with mine was that the windings on the rotor had become unwelded from the posts that are atached to the comutator. I guess at one point in its history that motor had overheated for some reason (my car cam in boxes so I have no idea of history). The fix was for me to re-tack them back on and all was good with the motor. All I had to do was remove the back cover, then remove the brushes and brush holders to get enough access to affect the repair.

If anyone needs to know what posts on the switch go were (since the diagrams don't show that), I can provide that now, just let me know. I am not at home right now and I don't remember off hand.