1969 headlights dimming???
Thread Starter
Cruising
Joined: Mar 2006
Posts: 14
Likes: 0
1969 headlights dimming???
Tonight I took the car for a drive and stopped for gas. It was getting dark so I turned on the headlights. The interior lights were all normal as far as brightness. On the dash the brights symbol for the high beams came on as well as both turn signal markers, not flashing though. I progressed home and the headlights continued to dim until they didn't funtion. I hit the high beams and it gave me a little light. Before I reached home they instantly returned to full brightness and the dash returned to normal, with the turn markers going off and the high beam marker going off. As I pulled up the drive it started again. The car runs fine and the interior lights seem fine. The voltage gauge reads almost 14 volts. Any ideas???
Thanks for any help.
Thanks for any help.
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Do you have a digital multi meter? Start checking things out. Battery, test it with the engine on and off. Off, somewhere north of 12V if it's healthy. On, 14+V.
Inspect the terminals and battery cables as far as you can see them. Are the cables swollen at all? This would indicate corrosion inside the protective jacket. Make sure the battery ground cable has good connections under the car, and I would even slide under the car and check your connections at the starter.
Then, go up to the alternator. With the engine off, check for 12+V at both the red wire going to the BAT lug on the alt, and from the red wire from the alt plug. With the engine off, the brown or white wire from the plug should have nothing. With the engine on, both red wires will still have 12+V but the brown or white wire will also have 12V.
I would suspect you have a bad ground or a bad power wire connection. Past that, the regulator or diode trio might be going out in your alternator and it's an intermittent symptom.
Inspect the terminals and battery cables as far as you can see them. Are the cables swollen at all? This would indicate corrosion inside the protective jacket. Make sure the battery ground cable has good connections under the car, and I would even slide under the car and check your connections at the starter.
Then, go up to the alternator. With the engine off, check for 12+V at both the red wire going to the BAT lug on the alt, and from the red wire from the alt plug. With the engine off, the brown or white wire from the plug should have nothing. With the engine on, both red wires will still have 12+V but the brown or white wire will also have 12V.
I would suspect you have a bad ground or a bad power wire connection. Past that, the regulator or diode trio might be going out in your alternator and it's an intermittent symptom.
Advanced
Joined: Dec 2006
Posts: 50
Likes: 1
From: So. Cal. CA
Check the High Beam Switch too
I had something similar happen. Don't know that I had ever used my high beams before, but one night I did, and my lights acted like you described. Was doing some research in the archives, and found a thread that said to check the High Beam Switch. Yup, mine was bad; had even melted the plastic connector 
Mike
Mike
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
I think if everything else was working fine and you had 14v on the gauge you can skip the battery and alternator and go directly to the headlight switch circuit. If it looks ok, then go thru the grounds for the headlights, make sure they are solid.
Having said that, its never a bad idea to look over the battery and alternator connections. I just don't think thats where your issue will be.
Having said that, its never a bad idea to look over the battery and alternator connections. I just don't think thats where your issue will be.
Thread Starter
Cruising
Joined: Mar 2006
Posts: 14
Likes: 0
Bingo!
Sure enough. A loose wire connection on the radiator support. I remedied this retapping the hole for a larger screw and
by adding another wire to it and running it to the motor/frame. Works perfect. Thanks for the input.
Racer
Joined: Jul 2004
Posts: 286
Likes: 1
From: Mesa az
You may want to look a bit further. That #14 on the radiator support isn't for the lights. All headlights get their "ground" returns via a wire inside the harness that runs back to the alternator. At least that's what the wiring diagram shows.
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