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MG MGA - wiper motor

I rebuilt the wiper motor for my project car and tested it using a jumper to the harness on my driver. The motor and gearbox worked great. After installing it in my project car along with the wheelboxes etc. it sat for 3 years. The car's wiring harness isn't installed yet so using a 12V battery, I ran wires to the motor today and I just get a click.

1. the battery shows only 10V on my multimeter. Could that cause it not to work?

2. how should I hook up the wires directly to a bettery?

Thanks, Fred
Fred H

If someone could please comment on this it would be helpful. I also have the same problem and have been watching this post for help.

Thanks.
L. Mazoway

I rebuilt a couple of wiper motors recently, no problems. One thing to note is that when testing the motor the cover must be in place (with the contacts assembled inside) over the drive gear. This threw me not just once, but twice! I rebuilt tested all ok then partially dismantled ready for assembly, tested again and of course nothing! If I remember correctly, the unit has a permanent live and a live from the switch. Connect earth and live and then short across the live terminals to check run and park function.
Neil McGurk

Wiper motors need quite a lot of current to drive them, so if your multimeter is accurate and is only showing 10v I would say your battery is not up to it. Can you try another battery or charge your existing one and then test it on a headlamp bulb to see if it lights that really well?
Lindsay Sampford

The wipers on the A are so anemic, that the only time you’ll ever use them is when you’re putting the car through state inspection—the rest of the time it’s Rain-X.
David werblow

Oh you fair weather drivers !

Switch the motor to a B two-speed one. My mods are detailed on Barney
dominic clancy

Check here:
http://mgaguru.com/mgtech/electric/et110.htm

The first requirement is of course, 12 volts power on "2" and a return ground on "E". Switch or jumper "1" to ground to make it run. Disconnect "1" and it should run to the park position.

Use power and ground jumper wires to do this to see if the motor works first. If not, then something is wrong in the motor. If it runs with jumper wires but not with the vehicle wiring, then fix the vehicle wiring.
Barney Gaylord

I have a somewhat related question. My inclination would have been to use my battery charger as an alternate direct power source if the battery's integrity was in question. Is that safe for the motor and myself?
Randy Myers

Randy

Depends on the battery charger. Not all have enough grunt to drive high current items like horns and motors (they are only suposed to trickle charge after al).

If you draw too much current the charger protection (fuse or trip) will blow.
dominic clancy

I finally figured it out on my own. I tried everything listed above and everywhere else. I tried a fully charged battery from another car and it didn't make any difference.

As a last resort I loosened up the 2 bolts holding the motor to the gearbox. That was it, the armature must have been pinched.

The 10v battery runs the wipers just fine now.
Fred H

This thread was discussed between 05/06/2009 and 22/06/2009

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