OK, pin 1 is ground, pin 2 is "Fast" when grounded, pin 3 is "Slow" when grounded, pin 4 is the connection to 12V, and pin 5 is an output signal indicating to the switch whether the wipers are home.
2. Check that there is no continuity between pin 5 and ground when the wipers are in the home position, and that there is continuity between pin 5 and ground when the wipers are away from home. The easiest way to get the wiper to move is to plug the wiper connector in and use the switch, turning off the key to get the wiper to stop where you want it to. (Assuming that your wipers automatically return home, otherwise you can get the wiper to stop anywhere you want it to simply by turning the switch on and off, this is not the preferred behavior, of course!)
If this test fails, it indicates that the internal switch is not working correctly. Please refer to the section on repairing the motor's internal switch below.
3. Check for less than 3 ohms resistance between pins 3 and 5 and pins 2 and 5 with the wipers in the home position.
If the resistance is greater than about 3 ohms, it indicates that the motor's internal switch is not working correctly. Please refer to the section on repairing the motor's internal switch below.
4. Connect pin 4 to the positive terminal of the battery. If at all possible, put a fuse in this wire so that you don't destroy something if you short it out. I recommend using insulated aligator clips for this kind of thing.
I would highly recommend that you create a test wire setup for tests similar to these. What works great for me is to use 14 gauge zip cord or speaker wire, to which I have soldered large alligator clips on one end (large enough to connect to the battery posts but smaller than jumper cable clamps!) and small, insulated alligator clips on the other end. Use black and red insulated alligator clips, and make sure that the colors match on the end of the wires. Traditionally, red is positive and black is negative. Make the wire long enough to reach from corner to corner on the car so that you can easily test or service the rear of the car. I have inserted an inline fuse holder in the positive conductor, about a foot back from the battery connector end. For most work, a 5 amp fuse is great. You won't fry too much if you create a short, and the fuse won't blow all the time. Another helpful item is male and female 1/4 inch spade connectors attached to short lengths of wire that can be attached to the alligator clips. This keeps you from having to try to get the clips into cramped quarters without creating shorts. All of this stuff is available at your local Radio Shack.)
5. Short pin 3 to ground. Wipers should run slowly. They will not return to home when the connection to ground is removed. This is normal.
If this test fails, it indicates that the slow winding in the motor is probably shot. The motor will have to be replaced.
6. Short pin 4 to ground. Wipers should run slowly. They will not return to home when the connection to ground is removed. This is normal.
If this test fails, it indicates that the fast winding in the motor is probably shot. The motor will have to be replaced.
If the motor passes all of these tests, move on to testing the wiper switch.
The switch inside the motor that indicates whether the motor is in the home position is located under the round plastic cover. It consists of conductive copper strips, attached to the nylon gear wheel, and 3 wiper contacts attached to the cover. Clos ure of the switches occurs when the wipers are in contact with the copper. What happens is that the contacts wear so badly that they float on the grease in the gear housing instead of making contact as they should. A short term repair is to clean the co ntact fingers and bend them slightly such that they are more perpendicular to the contact surface. It is likely that this repair will not last long, given the wear on the contacts. You will probably need to replace your motor. But it does work for a li ttle while, and it is pretty quick and easy.
Here's how:
1. Remove the three screws that hold the black cover onto the gear housing (it is not necessary to remove the motor from the car to perform this fix.) Pull the cover back out of the way.
2. Inspect the contact fingers for wear. If the switch is not working, one of them will likely appear very worn. Using some 600 grit sandpaper, polish up the contacts. Bend the contacts slightly such that the contact surface will b e more perpendicular to the surface of the gear. Don't bother trying to remove the grease.
3. Use the 600 grit sandpaper to polish up the conductive surface of the gear. Again, no need to bother trying to remove the grease.
4. Replace the cover and test the wipers. If there are still problems, move on to testing the wiper switch.
The windshield wiper switch (located in the cluster switch unit surrounding the instrument cluster) can be tested fairly thoroughly at the female connector that plugs into the windshield wiper motor. This way, it is not necessary to remove the switch unless it is found to be faulty.
The easiest way to test the switch is to construct a two-light test rig that also works great for setting the throttle position sensor. Simply get two 12V lights, solder two wires together into one 1/4 inch male spade connector, then solder the remain ing two leads into 1/4 inch spade connectors. Radio Shack sells lights that are perfect for this purpose and save you the effort of having to try to solder wires directly to light bulbs.
1. If you have the light test rig mentioned above, insert the common connector (the spade connector having two wires attached) into socket 4 of the connector, one of the remaining two wires into socket 3 of the connector and the last wire into socket 2 of the connector. If you don't have this handy dandy test rig, instructions are given for using an ohm-meter as well. A voltmeter can not be reliably used because it's high input impedance may yield an acceptable reading even with a h igh resistance connection inside the switch.
2. Turn on the ignition and set the wiper switch to slow speed. The light connected to socket 3 should turn on (brightly). If you are using an ohm-meter, you should measure nearly 0 ohms between socket 3 and ground. (Be careful not to touch the ohm-meter probe to socket 4 or your meter could be damaged.)
3. Set the wiper switch to fast speed. The light connected to socket 2 should turn on. If you are using an ohm-meter, you should measure nearly 0 ohms between socket 2 and ground.
4. Set the wiper switch to "Mist", the light connected to socket 3 should turn on while the switch is depressed. If you are using an ohm-meter, you should measure nearly 0 ohms between socket 3 and ground.
5. Set the wiper switch to "Intermittent" and turn the intermittent control knob (the knob in the center of the wiper switch) all the way counter-clockwise. The light connected to socket 3 should turn on and stay on. Momentarily gro und socket 5 and the light should turn off for a bit and then turn back on again. (This simulates the wiper returning home, ready for another cycle.) The amount of time that the light stays off each time this is done is determined by how long you have w aited between cycles. If you are using an ohm-meter, you should measure 0 ohms between socket 3 and ground when the above discussion describes the light as "on".
If your switch fails any of the above tests, it needs to be repaired or replaced. Due to the difficulty of disassembling the switch, repair is, for all practical purposes, out of the reach of the shade-tree mechanic. Those with good desoldering skill s can contact me (pstoaks@savantage.com) for the recipe. Otherwise, I am willing to perform this repair for a small fee if you are willing to mail me the part. Just contact me at the above address.
Removing the wiper switch from the instrument cluster is fairly straight-forward and can be accomplished without removing the steering wheel. Here is the procedure:
1. Remove the 4 screws under the steering column that attach the bottom half of the steering column cover.
2. Separate the bottom of the steering column cover from the top. The two pieces snap together with little clips that are attached to the bottom piece. Press in on the sides of the bottom piece while exerting gentle pressure downwar d to separate the pieces. There are two of these clips on each side and one on each side of the front of the cover. If you are careful, the two pieces can be separated without breaking the clips. If you break the clips, you will have annoying vibration s.
3. Remove the two screws on the bottom of the cluster switch cowl. There are 4 screws down there, you want to remove the two with the larger heads that are closer to the steering column on each side.
4. Remove the 3 screws on the underside of the top of the cowl, just above the instruments. Be careful not to scratch the instrument cover.
5. Pull the cowl out until it is stopped by the tension of the wires connected to the switches. You will probably need to do some wiggling and jockeying of the cowl relative to the top of the steering column cover. By persistent joc keying, you should be able to remove the top of the steering column cover (without breaking it).
6. Remove the connectors to the 4 switches. On all the switches except the turn signal, the locking tabs are on the inside of the connector, toward the steering column. (Yes, just to make you swear!) For the turn signal sw itch, the locking tab is on the bottom of the connector. Remove the connectors by pressing down the locking tab and wiggling the connector out.
7. Carefully remove the cluster from behind the steering wheel.
8. Place the cluster face down on a padded surface.
9. Pull the knobs off the switch. They are just pressed on. For the more stubborn knobs, gentle pressure against the center of the back of the knob (near the shaft) with a screwdriver placed against the switch body for leverage did the trick.
10. Remove the screws holding in the cruise control switch to loosen it.
11. Remove the screws holding in the wiper switch and wiggle it to remove it.
Again, if you want to attempt the repair yourself, contact me. Be forewarned, however, that it involves desoldering 20 very stubborn connections with some risk to the printed circuit board.
By Paul Stoaks pstoaks@savantage.com
If you discover any errors or can suggest any improvements, please contact the author.