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When I switch the high beams on, or less dramatically, off while driving, there is a momentary buck at the moment I hit the switch.
As far as I know, this does not happen when I switch on or off any other electrical components, but I guess I could test that in more detail. But for right now, it’s when I switch the high beams on or off. When I turn them on it is a single buck and pretty dramatic….
The battery is new and fully charged.
I just replaced the entire ignition system, soup to nuts.
The alternator is new.
That said, this issue was present prior to the work mentioned above.
There is no light flickering. The lights are bright, no dimming. The battery gauge ticks slightly when I hit the switch, but no more than I might expect… and less than it did before I swapped the alternator (the voltage regulator was on its way out in the old one).
It kind of started doing this out of nowhere awhile ago…. I can’t pinpoint when or what work I did when it started.
Just a guess here, the dimmer switch may have some corrosion on it creating resistance. Remove it, spray some contact cleaner in the switch and at the contact points on the wiring harness. Jerry
The MSD box is grounded to the frame at the same place the negative battery lead connects to the frame…. Highly unlikely it’s that, but maybe the head light high beam ground needs attention? Could a ground issue with the headlights make the ignition act up?? Just a guess that I’m looking for an affirmation of some kind… if that can’t be it, then not worth looking at.
Just a guess here, the dimmer switch may have some corrosion on it creating resistance. Remove it, spray some contact cleaner in the switch and at the contact points on the wiring harness. Jerry
Based on your profile name I assumed you have a 1980. Now that you stated the dimmer switch is on the floor you have a 1976 or older, what year is the car?
You mention an MSD box but give no details on what all of the modifications are to the ignition system. Please provide them.
Have you hooked up a voltmeter to the MSD box power wire and watched the reading when you turned on the high beam?
From: Loud, Raw and Dangerous 1968 327 4S in Southern California
When you did the ign. upgrade did you replace the RFI capacitors? Might be a noise issue with your MSD due to the headlight switch arcing when it switches. Here is a picture of one that is located at the voltage regulator.
Last edited by Redvette2; Sep 30, 2024 at 04:52 AM.
I couldn't wrap my head around this and even wondered if vacuum played a role.
But then something about after market ignition was mentioned,
I guess a power drop could be happening if headlight draw changes power to system?
When you did the ign. upgrade did you replace the RFI capacitors? Might be a noise issue with your MSD due to the headlight switch arcing when it switches. Here is a picture of the one that is located at the voltage regulator.
Based on your profile name I assumed you have a 1980. Now that you stated the dimmer switch is on the floor you have a 1976 or older, what year is the car?
You mention an MSD box but give no details on what all of the modifications are to the ignition system. Please provide them.
Have you hooked up a voltmeter to the MSD box power wire and watched the reading when you turned on the high beam?
The car is a 69. Ignition is MSD6AL. MSD coil, wires, distributor. As I mentioned… all brand new. But the problem appeared before the new ignition. Power wires to the MSD box are new as well.
I have not done what you suggested, but it’s worth a look at.
When you did the ign. upgrade did you replace the RFI capacitors? Might be a noise issue with your MSD due to the headlight switch arcing when it switches. Here is a picture of one that is located at the voltage regulator.
Thanks for the reply, but this is a 69 and the alternator has an internal regulator.
I couldn't wrap my head around this and even wondered if vacuum played a role.
But then something about after market ignition was mentioned,
I guess a power drop could be happening if headlight draw changes power to system?
Yea… but why would this just appear. I has MSD ignition before and after this issue appeared.
HOWEVER…. The MSD ignition box was previously a very old MSD 6.
It burned out one day a few years ago and I replaced it with a new MSD 6AL.
Now I do not recall if this issue appeared when I put the new MSD6AL box in or not.
But could putting an upgraded box over the very old 6 bring out an issue like this?
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Check all your grounds. If you have a bad ground in your ignition system it will find another ground source, same if your engine block isn't grounded well, or if your headlight ground isn't good....turning on or off the switch may be affecting the ground path. Especially since it's an old problem unrelated to the ignition upgrade
I would be running battery power to headlight relays. Using the old wiring and switches only to trigger a relay will use just the tiniest bit of power. It'll prolong the life of your old wiring and switches. Give you brighter headlights AND if voltage drop in your wiring is causing your buck. It'll now be gone.
my 2 cents.
I would be running battery power to headlight relays. Using the old wiring and switches only to trigger a relay will use just the tiniest bit of power. It'll prolong the life of your old wiring and switches. Give you brighter headlights AND if voltage drop in your wiring is causing your buck. It'll now be gone.
my 2 cents.
Running a relay for the lights is interesting.
Could I run the switch to the relay, as you said… but instead of power from battery, could I get power directly from the alternator instead?
I ask because the only direct battery power under the hood that I am aware of without splicing into something else, and without running through the firewall through the car to the battery itself, is to go to the starter… and I already have things running off the starter…. So the alternator seem like a good direct power source, but is that ok?
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High beam causing a buck
