Problem with my '70 headlights
Thread Starter
Intermediate
Joined: Jan 2004
Posts: 42
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From: Arecibo P.R.
Problem with my '70 headlights
Hello,
I'm having some electrical gremling on my '70. I'm replacing the lamps. I put 2 new halogen lamps in the driver's side. Still need to fight the passenger side. In the bright mode both lamps turn on, but in low beam, they both go off. Since the low beam has 3 prongs, I assume there are 2 elements, one for low beam and one for high beam. What voltage should I see in the low beam lamp connectors? Could this be related to the dimmer switch? Any guidance will be appreciated. By the way, I almost had to take the whole front of the car apart to remove the bezel so I could take the lamps out.
Thanks,
Ismael
I'm having some electrical gremling on my '70. I'm replacing the lamps. I put 2 new halogen lamps in the driver's side. Still need to fight the passenger side. In the bright mode both lamps turn on, but in low beam, they both go off. Since the low beam has 3 prongs, I assume there are 2 elements, one for low beam and one for high beam. What voltage should I see in the low beam lamp connectors? Could this be related to the dimmer switch? Any guidance will be appreciated. By the way, I almost had to take the whole front of the car apart to remove the bezel so I could take the lamps out.
Thanks,
Ismael
Melting Slicks
Joined: May 2004
Posts: 2,509
Likes: 525
From: Willowbrook IL
St. Jude Donor '13-'14-'15-'16
Power for your low beams comes from the TAN lead to the left headlamp. The right headlamp gets the power from the left side via a TAN wire.
Your dimmer switch is fed by the LIGHT BLUE wire fri=om the light switch. From the dimmer switch, TAN is for the low beams and the LIGHT GREEN is for the high beams.
So you should have 12 volts at the dimmer switch and at both leads coming from it. Start there. If you have power there go to the lighting harness connector on the firewall, the left connector. Check for power there. If it is there then trace the TAN wire to the left lamp. If it isn't there, the TAN wire is broken somewhere.
If you had a wiring diagram, it would help you.
Don
Your dimmer switch is fed by the LIGHT BLUE wire fri=om the light switch. From the dimmer switch, TAN is for the low beams and the LIGHT GREEN is for the high beams.
So you should have 12 volts at the dimmer switch and at both leads coming from it. Start there. If you have power there go to the lighting harness connector on the firewall, the left connector. Check for power there. If it is there then trace the TAN wire to the left lamp. If it isn't there, the TAN wire is broken somewhere.
If you had a wiring diagram, it would help you.
Don
Melting Slicks
Joined: Mar 2000
Posts: 2,801
Likes: 0
From: NJ
Originally Posted by ismaelg
By the way, I almost had to take the whole front of the car apart to remove the bezel so I could take the lamps out.
Thanks,
Ismael
Thanks,
Ismael
I'm starting to consider spending the $100 or so bucks to just buy new all rings and screws.
Let us know how you make out.
Dave
Thread Starter
Intermediate
Joined: Jan 2004
Posts: 42
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From: Arecibo P.R.
Don,
Thanks for the info. I replaced all 4 lamps and the passenger side work fine. That means the problem is only on the driver's side, after the junction that feeds the other side. As for taking the bezels out, I ended up removing the housing actuator screw (3/4" bolt) and loosing up the 2 screws on the side that hold the stop bolt so I could lift the whole thing hi enough for the bezels to come out.
Thanks,
Ismael
Thanks for the info. I replaced all 4 lamps and the passenger side work fine. That means the problem is only on the driver's side, after the junction that feeds the other side. As for taking the bezels out, I ended up removing the housing actuator screw (3/4" bolt) and loosing up the 2 screws on the side that hold the stop bolt so I could lift the whole thing hi enough for the bezels to come out.
Thanks,
Ismael
Melting Slicks
Joined: Mar 2000
Posts: 2,801
Likes: 0
From: NJ
Ismeal,
I just put the new lamps into my 70 and experienced the same exact problem that you are discribing. My wife, who has an engineering degree, suggested that there might be a problem with the contacts and it could be disrupting the ground.
Sure enough I went back, pulled out the lamps, cleaned and aligned the contacts, and now everyting works fine.
If you have not done so already I suggest you try this before you go pulling things apart chasing wires.
Good luck.
Dave
I just put the new lamps into my 70 and experienced the same exact problem that you are discribing. My wife, who has an engineering degree, suggested that there might be a problem with the contacts and it could be disrupting the ground.
Sure enough I went back, pulled out the lamps, cleaned and aligned the contacts, and now everyting works fine.
If you have not done so already I suggest you try this before you go pulling things apart chasing wires.
Good luck.
Dave
