softail817

Have a 74RR, the wipers won't park, they shudder a bit then die, replaced both the motor and the switch still having the same problem, any advice?

Chryco Psycho

Contact Kim AT Passion 4 Mopars

Mr.4spd

Ballast resistor.

softail817

really?, how would the ballast resistor be involved with the wiper motor?

bigblock

2 speed wipers have a ballast to make the first speed slower than the second.3 speed wipers dont have this.You must have 3 speed wipers.You need to find out what the car came with,to make sure the new parts you installed are compatible.

softail817

Car has a 2 speed switch, replaced the motor with what was in there when I got the car.

bremereric

Mr4spd failed to clarify. Your wiper motor itself has a ballast resistor mounted on it.

440roadrunner

Just to be correct, not every resistor is a "ballast." That resistor is in there for part of the speed control.

The whole idea of a "ballast" is to either regulate voltage or current, depending on the application. Ballasts are designed with materials which change resistance because of more/ less current, and therefore change current through the load.

Lamps are an example of changing resistance. A cold lamp draws a LOT more current when first starting to heat up than when after it's at full brilliance. This can become a problem in such things as very large power transmitting tubes. A "used to be" popular amateur radio PA tube "back when" was either a 3- or 4-1000A. These tubes had big filaments, They draw 21 amps at 7.5V, so two tubes are double that amperage.

An amateur radio "4 x 1" amplifier



Larger tubes are even more problematic An Eimac tube with 1 megawatt dissipation (that's right, 1 million watts) and capable of over 2 MW output in class C/ FM service, has a filament that runs at 16.3V at a whopping 625 amps!!!! You don't just turn those things on, as the cold "inrush" current is fantastic. The anode is liquid cooled:

http://home.comcast.net/~n6jv/data/X2159%20Ad.jpg

http://www.tubecollectors.org/eimac/archives/8974.pdf