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TR250 wiper motor wiring

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TR250 wiper motor wiring
#1
  This topic is about my 1968 Triumph TR250
TR5-2085 Jim Fitzpatrick
Allen, Texas, USA   USA
Hi. I'm looking for help on wiper motor wiring and, in particular, what the wiper motor switch does. I recently acquired a long stored 250 and I'm slowly getting the various systems up and running. So the wiper motor's installed in the vehicle and its a 3 wire unit with Green, red/green and brown/green wires fed from the harness.

With the ignition switched on each of these 3 wires register a 12V charge when I bridge to earth. I assume that's normal but I'm not sure.

At the switch, (which is broken), there are 3 wires - red/green, brown/green and black. With the ignition on the red/green and brown/green register 12V when bridged to earth. And the black wire zeroV. I assume its an earth.

So, 2 questions - are the voltages correct across the various wires?
And if they are how does the dash switch configure the circuit to energize the motor?

I'm thinking it could be as simple as connecting one of the live 12V dash switch circuits (say red/green) to earth (the black wire). Am I right? If so there's something wrong because the wiper motor doesn't start.

Thanks for the help.
Jim

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TR3driver Randall Y
Confusion, Los Angeles, USA   USA
We've gone around on this several times lately; seems like all the published diagrams are wrong (including the famous Dan Masters diagram).

It sounds strange, but what the switch does is ground one wire for high speed, and both wires for low speed. If you ground only the low speed wire, the motor won't run. I think (not certain) that the brown/green is the high speed and red/green is low.

Try connecting all 3 wires together (black, R/LG and N/LG) and see if the motor runs. If that works but just the black to N/LG doesn't, the resistor wire inside the motor may be burned out or broken.



Randall
56 TR3 TS13571L daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild

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Desert TR Gold Member Jim P
Albuquerque, New Mexico, USA   USA
Randall,

The red with light green stripe is the fast (high speed) connection and the brown with light green is the low speed. This is the mistake that is on the Auto-Wire schematic. (Their TR4A light switch is also wrong, at least wrt the original wiring.) As you indicated, grounding the red w lt. green will result in the motor running at max speed. Grounding both the red with lt. green and the brown w lt. green will result in the motor running at low speed. It shorts out some of the winding resulting in the lower speed, but the approach actual results in the motor drawing more current. Just a reminder, the motor case has to be grounded for the park function to work. It's amazing how well you remember after rebuilding the damn thing twice!

Jim

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Aphyle2012 Avatar
Aphyle2012 Silver Member Eric Pyle
Shenandoah Valley, VA, USA   USA
This is one of the topics that I was fussing with about 2 months ago, and I will add X2 on the advice above. It all makes sense in the context of the switch and the motor field coil. The center tab on the three-tab switch is the common line, and if you look at the switch internals, it does exactly what has been described. In one position (fast) it draws from one wire in the motor that has an extra 10-ohm length of resistance wire, which weakens the field strength relative to the motor armature, and it speeds up. When the switch is in the other position, both lines are engaged, the field strengthens, and the motor slows down. I think that I got that right.

Attached is the guide that was supplied to me, and allowed for the conversion of a 1-speed DR3A to 2-speed operation with minimal alterations and a 10-ohm resistor.


Attachments:
two-speed.pdf    292.1 KB

MonAndrew77 Avatar
MonAndrew77 Andrew M
Northern, Virginia, USA   USA
Hey folks.....

Sorry to jump in late on this topic, but on my TR250 I am hooking up the last bits of my new "Roadster Factory" OEM harness and I don't want to burn out the wiper motor. I confess I read through this and I'm still fuzzy..... I have the Masters book but now I'm a little gun-shy on the wiper motor connections.

I was thinking my TR250 motor is original, but now I'm not sure. It wasn't hooked up to the old harness when we took it out of the car.

On the motor, I have four terminals. From the bottom (furthest from the hood) the terminals are labeled:

(nothing)
"1"
"2"
"E"

You can see "E" is still grounded to the body.



On the new harness I have three wires:

Green
Red w/green
Brown w/green


How should I connect + and - leads to test the motor? I want to be sure it's working before I hook it up to the harness.

When I connect the new harness, how should I attach these three wires?


Many thanks....


Andrew


Attachments:
Wiper Motor 01.jpeg    57 KB
Wiper Motor 01.jpeg

Wiper Motor 02.jpeg    57.5 KB
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Aphyle2012 Avatar
Aphyle2012 Silver Member Eric Pyle
Shenandoah Valley, VA, USA   USA
From what I have learned via the forum here, you have a single-speed DR3A motor, not the two-speed that it should have. The green wire goes to the #2 contact, and the E goes to earth. That one is solely for the parking mechanism (red wire coming out of the top). The three-terminal switch should have the green wire going to the center contact, but I cannot remember off the top of my head which of the others is for "F" and "S" respectively. The problem with just wiring the motor in as-is is one wire will only get you slow speed. IIRC, I think that you need both of the other two wires just to get your motor to turn on at all.

There are ways to make it two-speed (see my previous query here) and the article above.



Edited 1 time(s). Last edit at 2017-02-20 11:45 AM by Aphyle2012.

TR3driver Randall Y
Confusion, Los Angeles, USA   USA
In reply to # 1436368 by Aphyle2012 The three-terminal switch should have the green wire going to the center contact,
Should be ground on a TR250. The dash switch grounds the motor to make it run continuously, while the park switch inside the motor grounds just to make it run to the park position.

This is different than the TR6 setup.



Randall
56 TR3 TS13571L daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild

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TR3driver Randall Y
Confusion, Los Angeles, USA   USA
In reply to # 1436365 by MonAndrew77 How should I connect + and - leads to test the motor? I want to be sure it's working before I hook it up to the harness.
To test, connect power (+12) to terminal 2 and ground terminal 1. That should make the motor run continuously. It actually doesn't care about polarity, but terminal 1 gets connected to the case (and terminal E) during part of the cycle.
Quote: When I connect the new harness, how should I attach these three wires?
If you're going to keep the TR250 switch and the single speed DR3A motor, then my suggestion would be to put green on terminal 2, and both the N/LG and R/LG to terminal 1. That way the motor will run at its one speed whether the switch is set to low or high. Also keep the jumper to E.



Randall
56 TR3 TS13571L daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild

MonAndrew77 Avatar
MonAndrew77 Andrew M
Northern, Virginia, USA   USA
Hey the motor works! I disconnected the ground to the frame and I ran hot to #2 and ground to #1. It's pretty slow but not TERRIBLY slow.

So bottom line is I defiantly have the wrong motor for a TR250 but it will work (slowly) with the above-mentioned connections? And you guys would swap it out for a correct motor......

I don't plan on getting caught in the rain and driving for very far, but no sense in having something incorrect in my car.

Funny how so many of these are incorrect. Did they die a lot and folks swapped them out back in the day with "whatever was available" used parts?

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TR3driver Randall Y
Confusion, Los Angeles, USA   USA
In reply to # 1436451 by MonAndrew77 Hey the motor works! I disconnected the ground to the frame and I ran hot to #2 and ground to #1. It's pretty slow but not TERRIBLY slow.

So bottom line is I defiantly have the wrong motor for a TR250 but it will work (slowly) with the above-mentioned connections? And you guys would swap it out for a correct motor......

I don't plan on getting caught in the rain and driving for very far, but no sense in having something incorrect in my car.

Funny how so many of these are incorrect. Did they die a lot and folks swapped them out back in the day with "whatever was available" used parts?
I would probably follow Eric's lead and try converting it to a 2-speed motor. You've already got the switch and wiring; and the change inside the motor looks pretty easy. Hardest part is probably figuring out just which wire to buy (different alloys, different diameters) and even that shouldn't be too hard a problem.



Randall
56 TR3 TS13571L daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild

Desert TR Avatar
Desert TR Gold Member Jim P
Albuquerque, New Mexico, USA   USA
Andrew,

I promised myself I would stay out of this one as it is a different motor than I'm used to and frankly I've kind of ODed on wiper motor questions! spinning smiley sticking its tongue out

If you have to disconnect the case from ground to get the motor to run, you don't quite have the wiring correct just yet. More than likely, you have the voltage to the motor reversed. It won't hurt the motor, but you won't have the park function. Here's what I suggest. Run the motor for a bit (half turn) and see if one of the terminals is connected to the case. If you then run the motor a bit again and it is no longer connected to the case, this is the connection that is grounded to give you your high speed. (Only speed in a single speed motor) The park internal terminal is connected to the high speed wire (Red with light green) on a three speed and the "run" wire on a two speed. This internal terminal contacts the case unless the motor has turned to the park position where it is insulated from the case. Since the case is grounded, the motor will run, even after the switch has been turned off and no longer grounding the high speed or run terminal, until the internal contact is aligned with the insulator. Bottom line, this means the high speed contact or the run contact in a two speed motor will be connected to the case through the park switch except for an area of about 15 degrees of rotation of the motor. Rotating the motor and then checking which terminal is in contact with the case all but 15 degrees of rotation will tell you which terminal is the "fast" or run connection when grounded.

Jim

TR5-2085 Jim Fitzpatrick
Allen, Texas, USA   USA
Just to keep the topic going...

I have the wiper motor working at 2 speeds by connecting wires at the dashboard - connecting red/green with black drives the motor at one speed and then brown/green with black drives motor at a different speed. I'm just happy it works to some degree!

Now I need a wiper motor switch, (preferably without filing out the metal dashboard frame). Any suggestions?

Thanks

MonAndrew77 Avatar
MonAndrew77 Andrew M
Northern, Virginia, USA   USA
Happy Spring Break guys... I'm working on the wipers finally.

Are we certain I have the "wrong" motor for my TR250? My car was built in Apr/1968.

In the Piggott Collectors' Originality Guide, paraphrased it says "the TR4 had two-speed wipers standard with the DR3A motor which was then carried over to the TR5."

Piggott then shows a DR3A from Sep/67 fitted to a TR250. In the book's photo the motor's info I can read are:

DR3A ~~~~~~~~~~~~~~~~~~~~~~1383A
12V 9 67 75568B


On my motor I have the following info suggesting my motor was made in Feb/1968:

DR3A [three-point star symbol] 54071383A
12V 2 68 75568B


What do you guys think? Can we tell from this data if my motor is two-speed or three speed? My motor has three terminals. My dash switch is a three position, four-terminal Clear Hooters model.

Many thanks, everyone.....


Attachments:
Piggott Wipers 1.JPG    74.8 KB
Piggott Wipers 1.JPG

Piggott Wipers 2.JPG    53.1 KB
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DR3 Motor 1.JPG    54 KB
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DR3 Motor 2.JPG    53.4 KB
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Desert TR Avatar
Desert TR Gold Member Jim P
Albuquerque, New Mexico, USA   USA
Andrew,

The motor appears to have two terminals and a case ground (E). The case ground is there so the park function will work. If it were a two speed motor, it would need three terminals plus the case ground. (+12, High Speed, and Low Speed)

Jim

TR3driver Randall Y
Confusion, Los Angeles, USA   USA
I think what you have there is a single speed ('off' normally isn't counted as a speed) motor that someone has put together using the gear housing from a two speed motor. A 75568 should normally be a 2-speed, but it would also have a bundle of wires sticking out rather than the two terminals.



Randall
56 TR3 TS13571L daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild


Attachments:
2 speed DR3A.jpg    41.1 KB
2 speed DR3A.jpg

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