Lights and Wiper door will not go down on 1968
08-12-2003, 08:08 PM
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Lights and Wiper door will not go down on 1968
Help, after not being able to leave well enough alone, I was adjusting some interior dash panels and doing some carb maitanance (just tightning nuts) on my 400hp car now my headlight and wiper doors will not go down. I cannot find any vacuum leaks and I have vacuum at the actuator switch that is mounted on the rear of the tach. How do I troubleshoot this system to find the cause? any help would be greatly appreciated. I got to get out and cruise Woodward this week and I want my doors down. :confused:
08-12-2003, 08:24 PM
#2
Team Owner
Re: Lights and Wiper door will not go down on 1968 (mac383)
I have vacuum at the actuator switch that is mounted on the rear of the tach.
You mentioned the solenoid behind the tach. I knocked a hose off of that thing and my wiper door popped open. But that shouldn't affect the headlights.... I think. A bit odd that both are up. That's why I asked the question above. :) MJ
08-12-2003, 08:44 PM
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Re: Lights and Wiper door will not go down on 1968 (MNJack)
The only dumb question is one that is'nt asked. I fooled with the overrides, but they are both closed, all hoses appear to be connected. Here is exactly what happened. I had my W/W switch unplugged, plugged it back in door came up, could not get door to go down, fooled with it, decided to try lights since vacuum is from same source,, lights up= John cruises Woodward looking like a dork unless I get this fixed.
08-12-2003, 11:01 PM
#4
Team Owner
Re: Lights and Wiper door will not go down on 1968 (mac383)
Both the lights and the wiper door are open?
And the lights were fine until you opened them and now they won't go down?
Sounds like you had vacuum going to the headlight relay but not to the wiper door relay. Is this possible? Hmmm..... shouldn't be actually. That's strange.
Ok, first of all, check to make sure both the small and large hoses are properly connected to the check valve under the hood and make sure you;re getting vacuum there. You are? Good.
Now check to see if you're getting vacuum to one of the big hoses that are attached to the wiper door actuator (that coffee can attached to the firewall). If the wiper door is open you shoudl be getting vacuum to the...let's see...push?...pull?....well, to one of them anyhow. Are you? yes? good.
Now do the same with the relay that's mounted under the nose of the car. You can get to it by opening the hood. It's right in the middle if you lean over & look in front of the radiator. Do the same thing there. Make sure you have vacuum going to one of the big hoses. While you're there, check the small hose for vacuum? Got it in one of the big hoses but not the small one? Then you have a problem on the control side of the system and not the actuator side of the system. This sucks, because the actuator side is much more accessible under the hood instead of behind the dash.
Assuming you've determined that your control side of the system is the problem. A quick aside here. The big tubes are the actuator side. They supply the vacuum that moves the actuators. The small tubes are the control side. They either supply vacuum to the relays or not. The relays are spring loaded 'vacuum switches'. With no control vacuum applied, they have an internal spring that moves the switch to supply vacuum to the "open" side of the actuator. This is the fail save mode, so if you lose control vacuum you still have lights and wipers. If there IS vacuum to the control side of the relay, it pulls against the spring and moves the relay to provide vacuum to the CLOSE side of the actuators.
From here, assuming that you have a control side problem, you have to simply go through the system systematically. Start at the check valve under hood. From there, the small hose goes through the firewall, then to a TEE. You shoudl have vacuum at both sides of that tee. From there, one hose goes to the wiper switch, then to the control valve under the dash and then to the headlight relay. The other side from the tee goes to the solenoid on the back of the tach, then to the override switch under the dash, and then back out to the wiper well to the switch out there. If any of those three switches has a vacuum leak, the wiper door will open due to lack of vacuum on the control side. Check along that path (you can actually start with the override switches since they're next to last in the chain) to make sure you have vacuum everywhere along that path.
Worst case, to get things closed, you can go to the relay up front and swap the big tubes. Then unhook the small tube. That'll make the fail-safe mode not closing the doors instead of opening them. Do the same at the coffee-can. Swap the hoses and the wiper door will close. That should get you going down Woodward for now. Just gotta swap those hoses back when it gets dark. :crazy:
Good luck!
Dave
And the lights were fine until you opened them and now they won't go down?
Sounds like you had vacuum going to the headlight relay but not to the wiper door relay. Is this possible? Hmmm..... shouldn't be actually. That's strange.
Ok, first of all, check to make sure both the small and large hoses are properly connected to the check valve under the hood and make sure you;re getting vacuum there. You are? Good.
Now check to see if you're getting vacuum to one of the big hoses that are attached to the wiper door actuator (that coffee can attached to the firewall). If the wiper door is open you shoudl be getting vacuum to the...let's see...push?...pull?....well, to one of them anyhow. Are you? yes? good.
Now do the same with the relay that's mounted under the nose of the car. You can get to it by opening the hood. It's right in the middle if you lean over & look in front of the radiator. Do the same thing there. Make sure you have vacuum going to one of the big hoses. While you're there, check the small hose for vacuum? Got it in one of the big hoses but not the small one? Then you have a problem on the control side of the system and not the actuator side of the system. This sucks, because the actuator side is much more accessible under the hood instead of behind the dash.
Assuming you've determined that your control side of the system is the problem. A quick aside here. The big tubes are the actuator side. They supply the vacuum that moves the actuators. The small tubes are the control side. They either supply vacuum to the relays or not. The relays are spring loaded 'vacuum switches'. With no control vacuum applied, they have an internal spring that moves the switch to supply vacuum to the "open" side of the actuator. This is the fail save mode, so if you lose control vacuum you still have lights and wipers. If there IS vacuum to the control side of the relay, it pulls against the spring and moves the relay to provide vacuum to the CLOSE side of the actuators.
From here, assuming that you have a control side problem, you have to simply go through the system systematically. Start at the check valve under hood. From there, the small hose goes through the firewall, then to a TEE. You shoudl have vacuum at both sides of that tee. From there, one hose goes to the wiper switch, then to the control valve under the dash and then to the headlight relay. The other side from the tee goes to the solenoid on the back of the tach, then to the override switch under the dash, and then back out to the wiper well to the switch out there. If any of those three switches has a vacuum leak, the wiper door will open due to lack of vacuum on the control side. Check along that path (you can actually start with the override switches since they're next to last in the chain) to make sure you have vacuum everywhere along that path.
Worst case, to get things closed, you can go to the relay up front and swap the big tubes. Then unhook the small tube. That'll make the fail-safe mode not closing the doors instead of opening them. Do the same at the coffee-can. Swap the hoses and the wiper door will close. That should get you going down Woodward for now. Just gotta swap those hoses back when it gets dark. :crazy:
Good luck!
Dave
