Electrical Windshield Wiper Problem

jrichker said:

What year is the car? The multifunction switches are year dependent: 87-89 are interchangeable, 90-93 are interchangeable.
BUT
You can't use a 90-93 switch in an 87-89 car, nor can you use a 87-89 switch in a 90-93 car. It will physically fit, but some things don't work, and if I remember correctly, the wipers are one of them.

Windshield wiper troubleshooting
How the 2 speed motor works:
The wiper motor does not have a resistor pack inside it. It does have one armature brush offset from the other two and a cylindrical permanent magnet instead of a set of field coils. The two brushes directly opposite each other are the low speed brushes. The low speed brush works in conjunction with one of the high speed brushes to provide a second speed.

Self Parking mechanism:

The self parking mechanism is copper circle glued or stuck on the wiper gear. The circle always has 12 volts on it until the wiper comes to the park position. There are two copper spring switch contacts, one provides power to the copper circle, while the other provides a path to the low speed winding. The power contact always provides power to the copper circle except when in the park position. The low speed contact is always in contact with the copper circle. When power is turned off at the wiper control, the 12 volts continues to flow to the low speed motor brush until the wiper blade returns to the park position.

Interval Governor:
The interval governor is a fancy electronic switch that sends the motor a pulse of electricity that varies in duration time. It always runs on the slow speed motor brushes. Turn the wipers on and quickly turn them off. The self parking mechanism inside the motor makes sure that the wiper blades come back to the park position and stop there. The interval governor does the same thing: it sends power to the wiper motor and then turns it off. The duration of the pulse sent to the motor determines how many strokes it makes before stopping at the park position. If you watch carefully, you will notice the wiper blade speed is constant and never changes when you are using the interval wiper function.

Troubleshooting:
All tests done with the ignition switch in Run or Accessory position and wipers on.
1.) Look for constant 12 volts on the red wire on the wiper motor. No 12 volts, the fuse is blown, bad wiring or bad connection. This will cause park problems or no wiper operation
2.) Check the ground. No ground and nothing works, bad ground and you get intermittent operation.
3.) No high speed operation, low speed OK. Look for 12 volts on the Dark Brown/orange wire. No 12 volts, bad wiper switch, bad connections or bad wiring.
4.) No low speed operation, high speed OK. Look for 12 volts on the white wire. No 12 volts, interval governor faulty or missing, or bad wiring. Since this is a pulse and not a steady voltage, a test light used in parallel with the voltmeter may be a better indication of operation
5.) Motor low speed test: Jumper the brown/white wire on the interval governor to the white wire. The motor should run in low speed mode. I haven’t tested this yet, so use caution. If the motor does not run, the low speed brush may be bad.

Do all this and by that time, maybe I’ll have figured out some simple tests for the interval governor…

See http://www.popularmechanics.com/cars/how-to/maintenance/how-to-fix-your-windshield-wiper-motors-2 for more help.[/quote



Thanks so much I will try this as soon as I am off of work today..by the way the mustang is a 89 gt convertible 5.0ho.. The multifunction switch and motor's all came out of 87,88,89 gt's

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jrichker said:

What year is the car? The multifunction switches are year dependent: 87-89 are interchangeable, 90-93 are interchangeable.
BUT
You can't use a 90-93 switch in an 87-89 car, nor can you use a 87-89 switch in a 90-93 car. It will physically fit, but some things don't work, and if I remember correctly, the wipers are one of them.

Windshield wiper troubleshooting
How the 2 speed motor works:
The wiper motor does not have a resistor pack inside it. It does have one armature brush offset from the other two and a cylindrical permanent magnet instead of a set of field coils. The two brushes directly opposite each other are the low speed brushes. The low speed brush works in conjunction with one of the high speed brushes to provide a second speed.

Self Parking mechanism:

The self parking mechanism is copper circle glued or stuck on the wiper gear. The circle always has 12 volts on it until the wiper comes to the park position. There are two copper spring switch contacts, one provides power to the copper circle, while the other provides a path to the low speed winding. The power contact always provides power to the copper circle except when in the park position. The low speed contact is always in contact with the copper circle. When power is turned off at the wiper control, the 12 volts continues to flow to the low speed motor brush until the wiper blade returns to the park position.

Interval Governor:
The interval governor is a fancy electronic switch that sends the motor a pulse of electricity that varies in duration time. It always runs on the slow speed motor brushes. Turn the wipers on and quickly turn them off. The self parking mechanism inside the motor makes sure that the wiper blades come back to the park position and stop there. The interval governor does the same thing: it sends power to the wiper motor and then turns it off. The duration of the pulse sent to the motor determines how many strokes it makes before stopping at the park position. If you watch carefully, you will notice the wiper blade speed is constant and never changes when you are using the interval wiper function.

Troubleshooting:
All tests done with the ignition switch in Run or Accessory position and wipers on.
1.) Look for constant 12 volts on the red wire on the wiper motor. No 12 volts, the fuse is blown, bad wiring or bad connection. This will cause park problems or no wiper operation
2.) Check the ground. No ground and nothing works, bad ground and you get intermittent operation.
3.) No high speed operation, low speed OK. Look for 12 volts on the Dark Brown/orange wire. No 12 volts, bad wiper switch, bad connections or bad wiring.
4.) No low speed operation, high speed OK. Look for 12 volts on the white wire. No 12 volts, interval governor faulty or missing, or bad wiring. Since this is a pulse and not a steady voltage, a test light used in parallel with the voltmeter may be a better indication of operation
5.) Motor low speed test: Jumper the brown/white wire on the interval governor to the white wire. The motor should run in low speed mode. I haven’t tested this yet, so use caution. If the motor does not run, the low speed brush may be bad.

Do all this and by that time, maybe I’ll have figured out some simple tests for the interval governor…

See http://www.popularmechanics.com/cars/how-to/maintenance/how-to-fix-your-windshield-wiper-motors-2 for more help.

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jrichker said:

You may have a problem with the parking switch. I had the copper disk come loose from the fiber gear. I didn't know that until I took the cover off that holds the wiper arm shaft. Once I saw that the copper disk was loose, I used some JB weld to glue it back in place. I used some very fine sandpaper to clean the copper disk. I also cleaned up the copper leaf contacts and reshaped them to put more pressure on the copper disk.[/quote


Ok I will give this a try next.thank you for all of your help.is there a way to check the high speed by jumping wires?when I did the low speed it worked continually until I unplug the wires put wouldn't start to work until I hit the washer function on the multifunction switch.. Humm still kinda puzzled about that...I'm very tempted to run a switch to the wires jumped lol but I definitely want it right I don't want to do any jack leg stuff like that..once again thanks for all of your help

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