Proverbial Windshield Wiper Problem
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Joined: Dec 2005
Posts: 61
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From: Kingman Arizona
Proverbial Windshield Wiper Problem
[FONT=Lucida Console][COLOR=Sienna] I would like an explanation of what happens electrically when the W/S/W switch is turned to lo to hi and pushed to activate washers... I have the Mid America vacumm trouble shooting guide and have a vacuum gage and have found several problems.. I understand the vacuum system pretty well (( yeah ))I am pretty sure the vacuum motor is bad.. The headlites work fine.. 
Where is this relay I see in schematics and what is its function????
Where is this relay I see in schematics and what is its function????
Le Mans Master
Joined: Aug 2003
Posts: 7,720
Likes: 12
From: Chattanooga TN
There is no vacuum motor, vacuum is supplied by the engine. You may meen the actuator.
As far as what happens when you flip the switch, there is a good explanation in the shop manual. Basically the motor has 12v when the ignition is on, the wiper door is open (electrical switch on firewall), and the override electrical switch under the column is closed. It has 12v to the washer relay(internal to the wiper motor) with ignition on. When you push in the washer you supply ground to that washer relay. When you go to low speed you supply ground to the unpark circuit and the low motor speed. When you go to high, you also get ground to the high speed circuit. In low or high you supply ground to the wiper (electric over vacuum) relay screwed to the tach which supplies vacuum to the (vacuum over vacuum) door relay underhood. A good ground to the switch is essential.
As far as what happens when you flip the switch, there is a good explanation in the shop manual. Basically the motor has 12v when the ignition is on, the wiper door is open (electrical switch on firewall), and the override electrical switch under the column is closed. It has 12v to the washer relay(internal to the wiper motor) with ignition on. When you push in the washer you supply ground to that washer relay. When you go to low speed you supply ground to the unpark circuit and the low motor speed. When you go to high, you also get ground to the high speed circuit. In low or high you supply ground to the wiper (electric over vacuum) relay screwed to the tach which supplies vacuum to the (vacuum over vacuum) door relay underhood. A good ground to the switch is essential.
Last edited by markdtn; Dec 22, 2005 at 12:27 PM.
