Headlamp / Wiper door issue
Thread Starter
Le Mans Master
Joined: Jul 1999
Posts: 5,005
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From: jackson nj
Headlamp / Wiper door issue
Today I replaced the broken vacuum hose on the headlamp switch in my 72 Vette, and although I've only had the car a short time, and the headlamps did not go down since I bought it, I figured replacing the broken hose would take care of it. When I was buying the car the owner told me the headlamps would not cycle, and there was a major vacuum leak from behind the dash, which was the broken hose, but the windshield wiper door and wipers worked. With replacing the hose, and confirming the routing with the diagram from both Wilcox and Zip, this now happens. The vacuum leak is gone, as expected, but when you pull the headlamp switch rod, the wiper door opens but the wipers don't cycle. If you move the wiper switch, the headlamps come up but don't turn on. The headlamps will turn on, if you pull the headlamp ****, but then the wiper door opens again......
Has anybody seen this happen, nothing I tried, including swapping hoses let the wipers turn on, and the doors opened just like before, wiper switch opens headlamps and headlamp switch opens wiper door only?
Has anybody seen this happen, nothing I tried, including swapping hoses let the wipers turn on, and the doors opened just like before, wiper switch opens headlamps and headlamp switch opens wiper door only?
Team Owner
Joined: Sep 2006
Posts: 31,283
Likes: 4,374
From: Westminster Maryland
Hi LB,
What is the result when you pull the vacuum override switches below the steering column… the left side is for the headlight doors and the right side for the wiper door.
These switches by-pass the headlight and wiper switches on the dash.
This will begin to tell you where the hoses are crossed.
Do you have the AIM sheet that shows the hose routing behind the left side dash pad?
Do you have access to those hoses now?
Regards,
Alan
You need to have UPC 12, Sheet B9 in front of you to trace the vacuum hose routing and connections. One sheet shows both the wiper and headlight hose routing.
The wiper door safety switch, which is mounted on the firewall, must be be triggered by the wiper door linkage in order for the wiper motor to run. Have you checked to see if the 'button' is being pushed when the door opens?
Here's the 'plunger' that pushes the button on the switch. It completes the circuit to the wiper motor.
Have you checked it?
What is the result when you pull the vacuum override switches below the steering column… the left side is for the headlight doors and the right side for the wiper door.
These switches by-pass the headlight and wiper switches on the dash.
This will begin to tell you where the hoses are crossed.
Do you have the AIM sheet that shows the hose routing behind the left side dash pad?
Do you have access to those hoses now?
Regards,
Alan
You need to have UPC 12, Sheet B9 in front of you to trace the vacuum hose routing and connections. One sheet shows both the wiper and headlight hose routing.
The wiper door safety switch, which is mounted on the firewall, must be be triggered by the wiper door linkage in order for the wiper motor to run. Have you checked to see if the 'button' is being pushed when the door opens?
Here's the 'plunger' that pushes the button on the switch. It completes the circuit to the wiper motor.
Have you checked it?
Last edited by Alan 71; Feb 24, 2017 at 08:42 AM.
Is my vette stock?? HAHA
Joined: Oct 2015
Posts: 20,221
Likes: 9,357
From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
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On a 68, the vacuum tees then goes to the headlight switch and tach sloenoid from there. yours should be the same. the only place they can be crossed and function are at the maintenance/ over ride switches. The wipers should function when the door is open, you mat have 2 problems. Fix the the doors first, then figure out the wipers. You may just have the wiper over ride switch turned on.
Last edited by Rescue Rogers; Feb 24, 2017 at 07:49 AM.
Thread Starter
Le Mans Master
Joined: Jul 1999
Posts: 5,005
Likes: 38
From: jackson nj
Hi LB,
What is the result when you pull the vacuum override switches below the steering column… the left side is for the headlight doors and the right side for the wiper door.
These switches by-pass the headlight and wiper switches on the dash.
This will begin to tell you where the hoses are crossed.
Do you have the AIM sheet that shows the hose routing behind the left side dash pad?
Do you have access to those hoses now?
Regards,
Alan
You need to have UPC 12, Sheet B9 in front of you to trace the vacuum hose routing and connections. One sheet shows both the wiper and headlight hose routing.
The wiper door safety switch, which is mounted on the firewall, must be be triggered by the wiper door linkage in order for the wiper motor to run. Have you checked to see if the 'button' is being pushed when the door opens?
Here's the 'plunger' that pushes the button on the switch. It completes the circuit to the wiper motor.
Have you checked it?
What is the result when you pull the vacuum override switches below the steering column… the left side is for the headlight doors and the right side for the wiper door.
These switches by-pass the headlight and wiper switches on the dash.
This will begin to tell you where the hoses are crossed.
Do you have the AIM sheet that shows the hose routing behind the left side dash pad?
Do you have access to those hoses now?
Regards,
Alan
You need to have UPC 12, Sheet B9 in front of you to trace the vacuum hose routing and connections. One sheet shows both the wiper and headlight hose routing.
The wiper door safety switch, which is mounted on the firewall, must be be triggered by the wiper door linkage in order for the wiper motor to run. Have you checked to see if the 'button' is being pushed when the door opens?
Here's the 'plunger' that pushes the button on the switch. It completes the circuit to the wiper motor.
Have you checked it?
As far as the "override" switches go, when I pull the LH one, the headlamps do go up, and when I pull the RH side the wiper door opens. The complete dash is out so I have decent access to all the "underdash" parts and when I removed the LH side, I found the hose cut from the headlamp switch to the tach solenoid, which I replaced (working on one hose at a time). When I bought the car, the headlamps were in the "up" position, and there was a massive vacuum leak behind the dash (broken hose to HL switch), but the wiper door worked fine...if not just a little slow.
I did find this afternoon that the "wiper vacuum switch on the firewall" is broken and the spring under the plunger is hanging out.
Alan, your car looks fantastic..!!
Last edited by Redvette_22; Feb 24, 2017 at 05:17 PM.
Thread Starter
Le Mans Master
Joined: Jul 1999
Posts: 5,005
Likes: 38
From: jackson nj
When I took the dash out (cleaning, checking wiring, etc.) there was only one hose that was broken, and it went to the HL switch, so I replaced it, and that is when this all happened. As a precaution, I did try to switch the solenoid vacuum hoses, but it did not correct anything.
Is my vette stock?? HAHA
Joined: Oct 2015
Posts: 20,221
Likes: 9,357
From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
2020 Corvette of the Year Finalist (performance mods)
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Last edited by Rescue Rogers; Feb 24, 2017 at 05:33 PM.
Is my vette stock?? HAHA
Joined: Oct 2015
Posts: 20,221
Likes: 9,357
From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
I think you may have #8 hose and letter H hose switched or #1 and letter G, YOu may want to trace all your hoses and get close to this diagram, Your year may vary but should be similar
Last edited by Rescue Rogers; Feb 24, 2017 at 05:36 PM.
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Safety Car
Joined: Apr 2006
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From: BC
I am waiting for the assembly manual to come in, but as I mentioned, I have the ZIP and Wilcox hose routing diagrams, do they have the same information you refer to UPC 12, Sheet B9..?
As far as the "override" switches go, when I pull the LH one, the headlamps do go up, and when I pull the RH side the wiper door opens. The complete dash is out so I have decent access to all the "underdash" parts and when I removed the LH side, I found the hose cut from the headlamp switch to the tach solenoid, which I replaced (working on one hose at a time). When I bought the car, the headlamps were in the "up" position, and there was a massive vacuum leak behind the dash (broken hose to HL switch), but the wiper door worked fine...if not just a little slow.
I did find this afternoon that the "wiper vacuum switch on the firewall" is broken and the spring under the plunger is hanging out.
Alan, your car looks fantastic..!!
As far as the "override" switches go, when I pull the LH one, the headlamps do go up, and when I pull the RH side the wiper door opens. The complete dash is out so I have decent access to all the "underdash" parts and when I removed the LH side, I found the hose cut from the headlamp switch to the tach solenoid, which I replaced (working on one hose at a time). When I bought the car, the headlamps were in the "up" position, and there was a massive vacuum leak behind the dash (broken hose to HL switch), but the wiper door worked fine...if not just a little slow.
I did find this afternoon that the "wiper vacuum switch on the firewall" is broken and the spring under the plunger is hanging out.
Alan, your car looks fantastic..!!
The only way it can work like that and it will, is if you have the vacuum lines reversed on the solenoid on the back of the tach. The diagram is correct but the solenoid is reversed orientation (facing the wrong way) in the Wilcox pic compared to the car. The vacuum hose off the T-fitting goes in the end without the sponge filter vent. The hose from the filter vent end goes to the wiper override pull down switch. Just reverse the hoses end for end on the wiper solenoid and you should be good to go. If these two hoses are mistakenly reversed on the wiper solenoid the override switches will work properly but the headlight switch and wiper switch vacuum functions are crossed.
Last edited by CanadaGrant; Feb 24, 2017 at 11:10 PM.
Thread Starter
Le Mans Master
Joined: Jul 1999
Posts: 5,005
Likes: 38
From: jackson nj
Is my vette stock?? HAHA
Joined: Oct 2015
Posts: 20,221
Likes: 9,357
From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
anytime