72 headlight issue
Thread Starter
Instructor
Joined: Nov 2004
Posts: 136
Likes: 0
From: Northern VA
72 headlight issue
Ok guys, thanks for all your help getting started. My wife and I cleaned the car up today so I'll be posting some great pics tomorrow. I can't believe what difference a good wash/wax had on the car. It's all vacuumed up, windows are clean and the wheels are polished. Absolutely incredible.
Now I have a problem...when I picked the car up, all the lights worked. Later that night the low beam lights wouldn't come on. However, when the high beams are on all of the lights come on. Any ideas before I get out there and start tearing things up?
BTW...I'm in Herndon, VA
Roy
Now I have a problem...when I picked the car up, all the lights worked. Later that night the low beam lights wouldn't come on. However, when the high beams are on all of the lights come on. Any ideas before I get out there and start tearing things up?
BTW...I'm in Herndon, VA
Roy
Melting Slicks
Joined: May 1999
Posts: 2,897
Likes: 0
From: Moon Township PA
The high/low switch is under your carpet and sometimes gets corroded or dirty. Try cycling the switch from low beams to high beams several times. If you see some hint of lights there then perhaps just cleaning the switch and its electrical contacts will help. I have had similar issues with a Chevy pickup. Lots of dirt and crud got into the switch and it took me less than 30 minutes to remove, clean, and reinstall.
Gary
Gary
Thread Starter
Instructor
Joined: Nov 2004
Posts: 136
Likes: 0
From: Northern VA
Ok the switch is out. I cleaned the contacts on both the switch and the connector without success. Does anyone know if you can test the switch. I found the NOS replacement but want to make sure before springing for it.
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
why are you using NOS stuff for this? why not an over the counter one from Pep boys? Its the same function and whos going to be crawling under your dash?
Drifting
Joined: Aug 2002
Posts: 1,731
Likes: 22
From: Marietta Ga.
You can test the switch with a power indicator. use a meter to read volts or use a tester with a light and see if power comes from the switch for dims at the headlight socket itself. The low beams have two filaments ,so if they work on high, it doesn't mean they aren't blown on low. You might try to run a power feed jumper to the back of the light and see if it works. If you don't have one, get a service manual with wiring diagrams.
Team Owner
Joined: Mar 2002
Posts: 24,160
Likes: 78
At the switch IIRC, green is high beam, tan is low
switch in -> continuity from blue to green
switch out -> continuity from blue to tan
that's all it does
In fact, if you want to verify that the switch was the culprit, you could just wire blue directly to tan and see if your low beams come on.
Also, before you pull all your hair out, check the low beam filaments themselves. Seems weird that they'd both go out at the same time, but it's not impossible I guess.
switch in -> continuity from blue to green
switch out -> continuity from blue to tan
that's all it does
In fact, if you want to verify that the switch was the culprit, you could just wire blue directly to tan and see if your low beams come on.
Also, before you pull all your hair out, check the low beam filaments themselves. Seems weird that they'd both go out at the same time, but it's not impossible I guess.
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Thread Starter
Instructor
Joined: Nov 2004
Posts: 136
Likes: 0
From: Northern VA
Evening all,
Just wanted to thank you for your help. If found that both of the low beam lights were blown. I'm sure it's unusual for both to go at once or in close succession. It was nice to take the headlight bezels off though. I got in there and cleaned everything up and then WD40'd all of the pivot points. Not only are all the headlamps working now, both of the assemblies come up with greater ease. I found that both of the headlights assemblies were rubbing on the plastic that acts as a protector when they're retracted. The assemblies were well spaced so I adjusted the position of the lower grills and voila, they both work great.
Next is the wiper door. I picked an Acutron vacuum tester and will begin that investigation this week.
thanks again,
roy
Just wanted to thank you for your help. If found that both of the low beam lights were blown. I'm sure it's unusual for both to go at once or in close succession. It was nice to take the headlight bezels off though. I got in there and cleaned everything up and then WD40'd all of the pivot points. Not only are all the headlamps working now, both of the assemblies come up with greater ease. I found that both of the headlights assemblies were rubbing on the plastic that acts as a protector when they're retracted. The assemblies were well spaced so I adjusted the position of the lower grills and voila, they both work great.
Next is the wiper door. I picked an Acutron vacuum tester and will begin that investigation this week.
thanks again,
roy
Team Owner
Joined: Mar 2002
Posts: 24,160
Likes: 78
The "blue" I was talking about was the hot to the floor switch. (not that it matters now) What color was yours? Age and exposure can change the colors of wires I've noticed.
Glad to hear you got it working. I guess on second thought it might not be all that weird for both to blow. You have to remember that the lows get cycled a lot more than the highs. And I suppose if one blew it would cause a little surge on the other which may kill it if it's already on its last legs? dunno ... ask an EE 
Originally Posted by Not2New72
Evening all,
Just wanted to thank you for your help. If found that both of the low beam lights were blown. I'm sure it's unusual for both to go at once or in close succession.
Just wanted to thank you for your help. If found that both of the low beam lights were blown. I'm sure it's unusual for both to go at once or in close succession.