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Prestolite wiper park function question |
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george w
Supporter of TheAMCForum Joined: Jan/27/2013 Location: New Jersey Status: Offline Points: 2899 |
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Posted: Jan/20/2021 at 12:26pm |
The David Bass rebuilt Prestolite wiper motor in my 67 Ambassador almost never wants to properly "park" the wipers when the switch is turned to off. Usually the wipers will simply stop in place or park half way up. I tried a new wiper switch and it made no difference. The wipers wipe normally as they should. As I'm sure most everyone knows removing the wiper motor to be sent back for fixing is a major pita. I'm assuming the problem is within the gear housing where the wires are connected. The gear case cover looks like it's reasonably easy to remove without the need to remove the entire motor. Does anyone have any experience what what is inside? The TSM shows a parking switch but gives no details or drawings on how it's supposed to be actuated. Maybe mine just has dirty or bad contacts or is somehow broken ? Help would be appreciated !
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Long time AMC fan. Ambassador 343, AMX 390, Hornet 360, Spirit 304 and Javelin 390. All but javelin bought new.
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6PakBee
Supporter of TheAMCForum Charter Member Joined: Jul/01/2007 Location: North Dakota Status: Offline Points: 5458 |
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I can't remember who posted this. I THINK it was either billd or 401MatCoupe but I am not sure. I know it wasn't me!! But I think this is what you are looking for. |
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Roger Gazur
1969 'B' Scheme SC/Rambler 1970 RWB 4-spd Machine 1970 Sonic Silver auto AMX All project cars. Forum Cockroach |
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ramblinrev
Moderator Group Joined: Dec/28/2008 Location: Wisconsin Status: Offline Points: 11543 |
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Ask BillD! Make sure that switch is grounded really good, as that's necessary for the park feature to work.
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74 Hornet Hatchback X twins (since 1977)
62 American Convertible (still worth the $50 I spent in 1973!) AMCRC #513, AMO #384 70 AMX 360 4-speed (since 1981) |
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george w
Supporter of TheAMCForum Joined: Jan/27/2013 Location: New Jersey Status: Offline Points: 2899 |
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Thanks, but not exactly what I'm looking for. This is the wiring diagram that's in the TSM. What I'm hoping for is a "look inside" the gear case cover to figure out how the park switch works mechanically and what it looks like. Since it works sporadically I'm assuming it's a contact problem but it could be worn in some way that it's not working or engaging as it should.
I'm trying to get a sense of what I may get into if I take that cover off while the wiper motor is still in the car. My fear is of flying springs and small parts when I take the cover off ! |
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Long time AMC fan. Ambassador 343, AMX 390, Hornet 360, Spirit 304 and Javelin 390. All but javelin bought new.
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george w
Supporter of TheAMCForum Joined: Jan/27/2013 Location: New Jersey Status: Offline Points: 2899 |
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Ramblinrev, I'm pretty sure that the switch is grounded OK to the dash through it's mounting shaft. It's tightly secured but I'll check it with a ohm meter just to be sure. The wiper's variable speed control function works properly and all the dash lights that illuminate the "lights", "wiper", "ignition", "lighter" and "a/c cooling" bezel lenses along the lower dash are lighting as they should. I'm almost 100% sure the issue is within the motor itself.
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Long time AMC fan. Ambassador 343, AMX 390, Hornet 360, Spirit 304 and Javelin 390. All but javelin bought new.
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george w
Supporter of TheAMCForum Joined: Jan/27/2013 Location: New Jersey Status: Offline Points: 2899 |
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Just confirmed with analog ohm meter that switch body to dash ground is good. 0 ohms reading on Rx1 scale.
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Long time AMC fan. Ambassador 343, AMX 390, Hornet 360, Spirit 304 and Javelin 390. All but javelin bought new.
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Steve_P
AMC Addicted Charter Member Joined: Jun/28/2007 Status: Offline Points: 3808 |
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The cam moves the rocker at the top which moves the contact arms.
Edit- this was disassembled and re-riveted. Edited by Steve_P - Jan/20/2021 at 4:11pm |
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george w
Supporter of TheAMCForum Joined: Jan/27/2013 Location: New Jersey Status: Offline Points: 2899 |
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That picture is a big help. Thanks !
It looks like those two copper contacts are normally out of the circuit when the wiper switch is turned on and when the wiper switch is turned to off power continues to the motor through the blue wire and those closed two copper contacts. These contacts are closed keeping the motor powered until the contacts open when the cam rotates to the position where the wipers are at the bottom of their path. From the way my wipers are acting it seems that these two copper contacts are either not touching, barely touching, corroded or contaminated so they're not making good contact when they're supposed to be closed. I'll be taking that cover off tomorrow to check things out ! |
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Long time AMC fan. Ambassador 343, AMX 390, Hornet 360, Spirit 304 and Javelin 390. All but javelin bought new.
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george w
Supporter of TheAMCForum Joined: Jan/27/2013 Location: New Jersey Status: Offline Points: 2899 |
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Took the cover off and opened up the housing this morning. I can't see where the pin on the guitar pick shaped rotating cam is supposed to engage
on the driven main gear. |
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Long time AMC fan. Ambassador 343, AMX 390, Hornet 360, Spirit 304 and Javelin 390. All but javelin bought new.
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FleetMaster
AMC Apprentice Joined: Jan/10/2020 Location: Northern Ind. Status: Offline Points: 56 |
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I know you checked the switch, what about the motor properly grounded? Had an issue on a very rusty brand X where the wiper motor would lose ground and keep cycling or park after a few more cycles. If the internal checks do not help, check that the motor is properly grounded when you remount.
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