How the wipers on my 68 work, long explanation.
08-24-2001, 01:16 AM
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How the wipers on my 68 work, long explanation.
A number of people asked me for my notes on the wiper system. Thought I'd post an explanation here. Don't know how to post pix, but I have a sketch and a couple of pictures I'd be more than happy to e-mail.
Vacuum works as follows,
Comes from the manifold into a filter, out of the filter is a 5/16" hose (little hose) which provide the "control" vacuum (Cvac) and a 3/8" hose (big hose) for "power" vacuum (Pvac). Pvac goes to the vacuum reservoir under the left fender near the break master cylinder. Pvac goes out of the reservoir up to the head light control valves up at the nose and another Pvac big hose goes over to the wiper control valve (WCV) under the right fender. For the wiper, there are 2 Pvac lines coming out of the WCV one provides OPEN vacuum to the back of the wiper actuator (on the firewall) and the other provides CLOSE vacuum to the front of the wiper actuator. The control valve works as follows: With vacuum on the Cvac (the small hose running to the wiper control valve) the Pvac is switched to the CLSOE hose, applying vacuum to the front of the wiper actuator. With no vacuum on Cvac, Pvac is switched to the OPEN hose and applies vacuum to the rear of the wiper actuator. Cvac works as follows,,,
Under the hood, the small hose coming off the filter goes in through the firewall and two Cvac lines come out the same bushing. One of these goes to the headlight control valves and one goes to the WCV. The Cvac control line comes into the car into a Tee. One side of the Tee goes to the light switch on the dash, and the other goes to the wiper solenoid vacuum input. The solenoid output is another Tee where the straight port is a vent and the right angel port is hosed to the wiper vacuum override switch (WVOS). Not sure WVOS is the right name but it’s the guy you pull down to manually open the wiper door. It is located below the tach on the lower dash pad panel. The way Cvac to the WCV works is as follows,,, with the solenoid deenergized and the WVOS pushed up, vacuum passes straight through out through the firewall and over to the WCV. When the WCV has vacuum then the wiper door is should be closed. If you pull down the WVOS, the vacuum supply line is blocked (so you don’t release the headlight Cvac) and the Cvac line to the WCV is vented, causing he door to open. Since this is in series with the Wiper solenoid it takes precedence. With the WVOS pushed in and the wiper solenoid energized, the Cvac supply is again blocked and the Cvac line to the WCV is vented once againm, opening the wiper door. Headlights work pretty much the same way except the headlight switch on the dash performs the function of the wiper solenoid.
The trick with the wiper door is to open the door before the wipers start and close the door after the wipers have parked. This is the electrical part. The wiper motor has three wires one is POWER, the other two are GROUND. One ground is an ENABLE or RUIN, motor won't run without this ground, the other ground is a speed select. No ground (or open) on the speed select line is FAST and ground on the speed select line is SLOW. These wires come through a grommet in the motor body. One, the ENABLE or RUN ground goes through a plug to the wiper door open limit switch (located on the firewall) then on through the wiper override switch (on the same panel below the tach with the WVOS). If the wiper override switch is off ground is removed and the wiper motor stops were it is (used to service the wiper blades) if the wiper door limit switch is not made the run ground is also remove and the motor stops. That's the easy part.
Motor power and the speed select come from the park switch, which is located in the wiper motor hosing. The park switch does two things: it applies power to the wiper solenoid, causing it to engage and apply an "OPEN" vacuum signal (ie no vacuum) to the WCV) whenever the wiper motor is not in the parked position. So if there is 12V on the brown wire to the wiper solenoid, the motor is not parked. If there is no 12V on the brown wire the solenoid is not energized. (BTW the wiper solenoid is in the wiring harness on the right hand side of the tach.) The other thing the park switch does is keep 12V on the wiper motor after the wiper switch is turned off until the wipers park. When the wipers park, the motor stops and the wiper solenoid disengages. Power to the park switch on the yellow wire come from the ignition switch when the key is ON or ACC. The wiper switch works by connecting ground to various control points in the system. This is the switch above the gage panel and is the root of a lot of problems because of a bad ground or the fact the connector will fit either way but will only work in the correct orientation. When the wiper switch is in either ON position there should be a ground on both of the light blue (lbl) wires. One causes the wiper relay (not the solenoid) to energize and connect the center (B) post of the wiper switch to the light green (lg) wire going into the park switch. This lg wire carries the speed select (gnd = SLOW, open = FAST). The other lbl goes to the park switch to set the park switch to the run position, which supplies 12V on Brown to the wiper solenoid. IF the wiper door opens and makes the wiper limit switch, which completes the motor ENABLE circuit by grounding the motor. Wipers working, park switch is engaged.
When the wiper switch is turned off, removing all the grounds, the wiper relay is deenergized connecting a ground to the speed select making the motor run at slow speed and removes ground from the park switch. With the park switch denergized, when the wiper motor this finall cycle and returns to the park position, the park switch returns to the parked position removing power from the motor and the wiper door solenoid. When the wiper door solenoid deenergizsed, vacuum is applied to WCV Cvac causing the door to close.
DISCLAIMER: This is how MY 68 works, BUBBA MAY HAVE WORKED ON IT! But, I say again, this is how MY 68 works. I've heard rumors of an additional "safety" switch on later model C3s. I don't know anything about this. I would guess it works like the wiper override switch or the door limit switch. Heard it is under the door on the passenger’s side and makes sure the wipers are parked.
:cheers:
Hope this helps,
Vacuum works as follows,
Comes from the manifold into a filter, out of the filter is a 5/16" hose (little hose) which provide the "control" vacuum (Cvac) and a 3/8" hose (big hose) for "power" vacuum (Pvac). Pvac goes to the vacuum reservoir under the left fender near the break master cylinder. Pvac goes out of the reservoir up to the head light control valves up at the nose and another Pvac big hose goes over to the wiper control valve (WCV) under the right fender. For the wiper, there are 2 Pvac lines coming out of the WCV one provides OPEN vacuum to the back of the wiper actuator (on the firewall) and the other provides CLOSE vacuum to the front of the wiper actuator. The control valve works as follows: With vacuum on the Cvac (the small hose running to the wiper control valve) the Pvac is switched to the CLSOE hose, applying vacuum to the front of the wiper actuator. With no vacuum on Cvac, Pvac is switched to the OPEN hose and applies vacuum to the rear of the wiper actuator. Cvac works as follows,,,
Under the hood, the small hose coming off the filter goes in through the firewall and two Cvac lines come out the same bushing. One of these goes to the headlight control valves and one goes to the WCV. The Cvac control line comes into the car into a Tee. One side of the Tee goes to the light switch on the dash, and the other goes to the wiper solenoid vacuum input. The solenoid output is another Tee where the straight port is a vent and the right angel port is hosed to the wiper vacuum override switch (WVOS). Not sure WVOS is the right name but it’s the guy you pull down to manually open the wiper door. It is located below the tach on the lower dash pad panel. The way Cvac to the WCV works is as follows,,, with the solenoid deenergized and the WVOS pushed up, vacuum passes straight through out through the firewall and over to the WCV. When the WCV has vacuum then the wiper door is should be closed. If you pull down the WVOS, the vacuum supply line is blocked (so you don’t release the headlight Cvac) and the Cvac line to the WCV is vented, causing he door to open. Since this is in series with the Wiper solenoid it takes precedence. With the WVOS pushed in and the wiper solenoid energized, the Cvac supply is again blocked and the Cvac line to the WCV is vented once againm, opening the wiper door. Headlights work pretty much the same way except the headlight switch on the dash performs the function of the wiper solenoid.
The trick with the wiper door is to open the door before the wipers start and close the door after the wipers have parked. This is the electrical part. The wiper motor has three wires one is POWER, the other two are GROUND. One ground is an ENABLE or RUIN, motor won't run without this ground, the other ground is a speed select. No ground (or open) on the speed select line is FAST and ground on the speed select line is SLOW. These wires come through a grommet in the motor body. One, the ENABLE or RUN ground goes through a plug to the wiper door open limit switch (located on the firewall) then on through the wiper override switch (on the same panel below the tach with the WVOS). If the wiper override switch is off ground is removed and the wiper motor stops were it is (used to service the wiper blades) if the wiper door limit switch is not made the run ground is also remove and the motor stops. That's the easy part.
Motor power and the speed select come from the park switch, which is located in the wiper motor hosing. The park switch does two things: it applies power to the wiper solenoid, causing it to engage and apply an "OPEN" vacuum signal (ie no vacuum) to the WCV) whenever the wiper motor is not in the parked position. So if there is 12V on the brown wire to the wiper solenoid, the motor is not parked. If there is no 12V on the brown wire the solenoid is not energized. (BTW the wiper solenoid is in the wiring harness on the right hand side of the tach.) The other thing the park switch does is keep 12V on the wiper motor after the wiper switch is turned off until the wipers park. When the wipers park, the motor stops and the wiper solenoid disengages. Power to the park switch on the yellow wire come from the ignition switch when the key is ON or ACC. The wiper switch works by connecting ground to various control points in the system. This is the switch above the gage panel and is the root of a lot of problems because of a bad ground or the fact the connector will fit either way but will only work in the correct orientation. When the wiper switch is in either ON position there should be a ground on both of the light blue (lbl) wires. One causes the wiper relay (not the solenoid) to energize and connect the center (B) post of the wiper switch to the light green (lg) wire going into the park switch. This lg wire carries the speed select (gnd = SLOW, open = FAST). The other lbl goes to the park switch to set the park switch to the run position, which supplies 12V on Brown to the wiper solenoid. IF the wiper door opens and makes the wiper limit switch, which completes the motor ENABLE circuit by grounding the motor. Wipers working, park switch is engaged.
When the wiper switch is turned off, removing all the grounds, the wiper relay is deenergized connecting a ground to the speed select making the motor run at slow speed and removes ground from the park switch. With the park switch denergized, when the wiper motor this finall cycle and returns to the park position, the park switch returns to the parked position removing power from the motor and the wiper door solenoid. When the wiper door solenoid deenergizsed, vacuum is applied to WCV Cvac causing the door to close.
DISCLAIMER: This is how MY 68 works, BUBBA MAY HAVE WORKED ON IT! But, I say again, this is how MY 68 works. I've heard rumors of an additional "safety" switch on later model C3s. I don't know anything about this. I would guess it works like the wiper override switch or the door limit switch. Heard it is under the door on the passenger’s side and makes sure the wipers are parked.
:cheers:
Hope this helps,
08-24-2001, 01:52 AM
#2
Burning Brakes
Re: How the wipers on my 68 work, long explanation. (rickales)
Thank you for this post!!. I had wiper problems just yesterday and I searched everywhere for vacuum and wiring diagrams. Every book I have just kind of glossed over how they really work. Luckily I found a loose electrical connection and fixed mine. If it would have been a harder fix then I would have had real problems. I printed your post and filed it just in case of future problems.
:cheers: :cheers: :cool: :cool: :cheers: :cheers:
:cheers: :cheers: :cool: :cool: :cheers: :cheers:
08-24-2001, 07:56 AM
#3
Senior Member since 1492
Re: How the wipers on my 68 work, long explanation. (greg454)
Thanks for the explaination Rick. I'm still working on mine...just need some time. I'll print this post out for use later. Your description sounds pretty close to the setup I have. On the passenger side firewall though, I've got a grommet with three hoses going to a valve in the left side corner. Problem is that while passing thru the gromet only two of the hoses come thru. Bubba CUT the third and bottom hose! I think this is why my wiper door won't open via the switch. I can't figure out though, where this third hose would connect to in the engine side!:confused: I can't find another cut or OPEN vacuum connection to slice the cut hose.
08-24-2001, 08:45 AM
#4
Le Mans Master
Re: How the wipers on my 68 work, long explanation. (rickales)
I have a copy of the Headlight & Wiper Door vacuum troubleshooting guide from Eckler's ($9.99). It has a very extensive but easy to understand write up explaining the system and very good diagrams of the hoses for the C3s. This is another time I wish I had a scanner so I could post it to an email to you. Was definitely worth the money when I need to fine tune my lights. :yesnod:
08-24-2001, 10:50 AM
#5
Burning Brakes
Re: How the wipers on my 68 work, long explanation. (rickales)
Rick,
Great explanation.
For those that don't care for the original design, I have a functional electric motor/actuator pushing my door up and down.
To me, it is a better alternative than switching to a long hood, or fighting pesky vacuum problems.
Great explanation.
For those that don't care for the original design, I have a functional electric motor/actuator pushing my door up and down.
To me, it is a better alternative than switching to a long hood, or fighting pesky vacuum problems.
08-24-2001, 11:03 AM
#6
Burning Brakes
Re: How the wipers on my 68 work, long explanation. (rickales)
70 stingray, my car has those same 3 hoses coming through the grommet and one of them is cut off just like your and my door and wipers work perfectly! go figure. :crazy: