Topic: Wipers don't work
in Forum: C3 Electrical
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The wipers on my 75 do not work. The wiper motor does work. I am able to connect the wiper motor terminals to external battery.
I used a Voltmeter to read 12V on the cable going to the wiper motor. I also read 12V on the cable that connects to the wiper switch. I'm thinking I have a ground issue. I used a jumper wire to the wiper switch to see if I get any movement with the wipers. I connected 1 end to ground and the other end to one of the wiper switch mounting screws. Still no wiper movement.
The fact that I can get the wipers to work with external battery and cables tells me I probably have a ground issue or bad wire. Does anyone have any suggestions.
One interesting thing to note. I checked for voltage drop on the ground side. Using Voltmeter I connected the black lead to the negative battery post and the red lead to the ground terminal on the wiper motor. I got a reading of 12V with no wiper action. Does that make sense? I'm just learning all this electrical stuff.
As always thanks for the help.
Rich
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Lifetime MemberLanoka Harbor, NJ - USA
Joined: 12/21/2006
Posts: 828
Vette(s): 1975 metallic blue coupe with t-tops,L48, t/t steering, black leather interior. 1990 L98, white/red leather interior, auto,a/c
if i understand you correctly, you are getting a 12v reading on the
positive wire at the motor.my suggestion would be to take a wire and
connect it to the negative side of motor and ground it out. you would
be bypassing the negative wire and if wipers work with the extra wire
grounded then you would have a bad negative wire. hope this helps.
LIFETIME MEMBER #97
THE DYNAMIC DUO
THE DYNAMIC DUO
Lifetime MemberModerator
Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
The wiper motor works off of a ground signal from the switch. Sorta back-wards from "normal".
The wiper motor should have 12v anytime the key is on. The switch provides different ground paths(resistance) for the different speeds. Check to make sure the wiper switch itself is properly grounded first. More than one person has spent days trying to figure this one out, only to find the wiper switch wasn't screwed into the dash correctly, or...the plug was up-side down!
Run your jumper wire from a good ground to the wiper switch casing, and see what happens.
The wiper motor should have 12v anytime the key is on. The switch provides different ground paths(resistance) for the different speeds. Check to make sure the wiper switch itself is properly grounded first. More than one person has spent days trying to figure this one out, only to find the wiper switch wasn't screwed into the dash correctly, or...the plug was up-side down!
Run your jumper wire from a good ground to the wiper switch casing, and see what happens.
Joel Adams
C3VR Lifetime Member #56 
My Link 
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
Lifetime MemberLanoka Harbor, NJ - USA
Joined: 12/21/2006
Posts: 828
Vette(s): 1975 metallic blue coupe with t-tops,L48, t/t steering, black leather interior. 1990 L98, white/red leather interior, auto,a/c
figures they would make it bass ackwards to confuse the heck out of everyone. good thing joel was here to save the day
.
.
LIFETIME MEMBER #97
THE DYNAMIC DUO
THE DYNAMIC DUO
David/Joel,
Thanks for the help. I ran my jumper wire from the ground on the wiper motor to ground on the engine and the wipers worked. I also ran the jumper wire from ground on the wiper motor to the plate where the wiper switch is located and the wipers worked. Using voltmeter I tested the gound wire that goes for the wiring harness into the wiper motor and it looks bad. So I guess its the ground cable going to the wiper motor, maybe pinched, or perhaps a loose ground connection in the console?
Lifetime MemberModerator
Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
The switch itself has to be grounded to provide a ground to the wiper motor. You need to correct that first. The switch normally has a small wire attached to one of the screws that hold it to the bezel. If your's doesn't have this wire, try putting one on it from a good ground source. I think this will solve the problem.
Joel Adams
C3VR Lifetime Member #56
My Link
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
Lifetime MemberManteca, CA - USA
Joined: 11/20/2005
Posts: 3623
Vette(s): 1978,two tone,Metalic Rootbeer & gold
1975 L48 4 speed
Excellent gentlemen ! The first problem we encountered on the trip to the gathering was the wifes wipers came on and went off by themselves, leaving the wipers in the middle of the windshield. had to remove the arms entirely. I very much appreciate the education BEFORE I get started on it. I'll get 'er done in a short time.
Jimmy B.
Just can't wait to get on the road again. 
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Lifetime MemberModerator
Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
[QUOTE=Adams' Apple] The switch itself has to be grounded to provide a ground to the wiper motor. You need to correct that first. The switch normally has a small wire attached to one of the screws that hold it to the bezel. If your's doesn't have this wire, try putting one on it from a good ground source. I think this will solve the problem. [/QUOTE]
Otay...after reading this again, I feel I should clarify my statement...
What I should have said was, "The switch usually has a small wire attached..." because that's the only way someone else could get it to work!
In reality, the switch is supposed to be grounded by the bezel, which is a cast metal piece, and is screwed into a metal part of the dash cross-bracing. That's the way they were...by now, however, the bezel has been in-out of the dash 100 times, and it is no longer capable of providing the wiper switch with a ground, and that is normally because the screw hole threads are stripped, or the particular screws are not even there anymore. That's why most of the ones I see have the extra wire-ground added.
Also, the wipers will not normally work if the bezel is un-attached to the dash...another reason for the extra wire!
Sorry if my statement was mis-leading, or, heaven forbid, confusing!
need sleep...
[/QUOTE]
Otay...after reading this again, I feel I should clarify my statement...
What I should have said was, "The switch usually has a small wire attached..." because that's the only way someone else could get it to work!
In reality, the switch is supposed to be grounded by the bezel, which is a cast metal piece, and is screwed into a metal part of the dash cross-bracing. That's the way they were...by now, however, the bezel has been in-out of the dash 100 times, and it is no longer capable of providing the wiper switch with a ground, and that is normally because the screw hole threads are stripped, or the particular screws are not even there anymore. That's why most of the ones I see have the extra wire-ground added.
Also, the wipers will not normally work if the bezel is un-attached to the dash...another reason for the extra wire!
Sorry if my statement was mis-leading, or, heaven forbid, confusing!
need sleep...
Joel Adams
C3VR Lifetime Member #56
My Link
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
Let me just add, if the extra ground wire is not on the switch, put it there just to avoid problems in the future.
Joel is right on the money.
in Forum: C3 Electrical
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