All lights flicker when running
- Thread starter coalman
- Start date
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Chances are it's a ground issue - somewhere.
Light switch could be going.
67Dart273
Well-Known Member
Do you still have the old electro--mechanical regulator?
Like this?
The way to determine if it's mechanical or electronic is look at the bottom. If there are two large wirewound resistors, it is mechanical. If not, it's electronic. This is an original mechanical
There is quite a few issues if you have factory old wiring. Grounding, bad connections, the mentioned dimmer switch, and the regulator and connections.
This can ALSO be a problem in the charging system
Bad connections in the alternator output path, worn brushes in the alternator, as well as the old style regulator
Like this?
The way to determine if it's mechanical or electronic is look at the bottom. If there are two large wirewound resistors, it is mechanical. If not, it's electronic. This is an original mechanical
There is quite a few issues if you have factory old wiring. Grounding, bad connections, the mentioned dimmer switch, and the regulator and connections.
This can ALSO be a problem in the charging system
Bad connections in the alternator output path, worn brushes in the alternator, as well as the old style regulator
Rapid Robert
Well-Known Member
X2 & reg at the top of that (2) item suspect list (if wire wound resistors "old style" reg) & if not WW type then it ain't even on the list
chryslerfat
Well-Known Member
Usually caused by the old regulator.
gdizzle
Well-Known Member
i was told it is alternator. So if it ends up being the regulator I would be very interested. Keep us informed
BillGrissom
Well-Known Member
Do you mean just dash and cabin lamp or headlamps too? Look for a common source, such as dimmer for the first two, or I think the ACC supply for all 3 (fuse, key switch, headlamp switch).
67Dart273
Well-Known Member
This could be an odd "ground loop" so to speak, a problem with the regulator, alternator brushes, or problems in the bulkhead connector / ammeter / light switch circuit.
First thing to do is try and more define the problem. Get the thing warmed up and normalized, and try and determine if there's a "favorite" condition in which this occurs, IE dead slow idle, fast idle, low cruise RPM, etc.
Monitor battery voltage and record it. Turn lights off and see if voltage stabilizes. Now try and duplicate the load which the lights put on the system, that is, recheck battery voltage with radio / stereo, heater, etc powered on.
Best, if you can, to "drum up" a carbon pile tester, then you can vary the load.
Read this MAD article:
http://www.madelectrical.com/electricaltech/amp-gauges.shtml
Watch "whut it does" and determine if it's random or "rhythmic" If it's random, probably a loose connection. If it has a rhythm, probably some sort of loop
EXAMPLE.......loose connection in some circuit causes charging voltage to sag, regulator tries to compensate and at some point the connection "makes" because of the rising voltage, now the regulator must drop back down, over...and over.........
Check regulator grounding and check regulator supply voltage for "harness voltage drop."
To do that, run engine, warm, all accessories off, and repeat with lights, heater, etc on.
Check the ground by stabbing one meter probe into the top of the NEGative battery post. The post, not the cable clamp. Stab the remaining probe into the mounting flange of the voltage regulator. You want a very very low voltage, the lower the better, and zero is perfect. Over .2V (2/10 of one volt) means you have a grounding problem. Regulator MUST be at same voltage as battery NEG
Now check the harness. Turn off engine, turn key back to "run." Stab one probe of your meter into the top of the POSitive battery post. Stick the other probe into the connector for the IGN terminal of the VR. Again you want to see a very low reading. Over .3V or so (3/10) is too much, and indicates a voltage drop from the battery, through the various connectors and ignition switch, to the regulator.
First thing to do is try and more define the problem. Get the thing warmed up and normalized, and try and determine if there's a "favorite" condition in which this occurs, IE dead slow idle, fast idle, low cruise RPM, etc.
Monitor battery voltage and record it. Turn lights off and see if voltage stabilizes. Now try and duplicate the load which the lights put on the system, that is, recheck battery voltage with radio / stereo, heater, etc powered on.
Best, if you can, to "drum up" a carbon pile tester, then you can vary the load.
Read this MAD article:
http://www.madelectrical.com/electricaltech/amp-gauges.shtml
Watch "whut it does" and determine if it's random or "rhythmic" If it's random, probably a loose connection. If it has a rhythm, probably some sort of loop
EXAMPLE.......loose connection in some circuit causes charging voltage to sag, regulator tries to compensate and at some point the connection "makes" because of the rising voltage, now the regulator must drop back down, over...and over.........
Check regulator grounding and check regulator supply voltage for "harness voltage drop."
To do that, run engine, warm, all accessories off, and repeat with lights, heater, etc on.
Check the ground by stabbing one meter probe into the top of the NEGative battery post. The post, not the cable clamp. Stab the remaining probe into the mounting flange of the voltage regulator. You want a very very low voltage, the lower the better, and zero is perfect. Over .2V (2/10 of one volt) means you have a grounding problem. Regulator MUST be at same voltage as battery NEG
Now check the harness. Turn off engine, turn key back to "run." Stab one probe of your meter into the top of the POSitive battery post. Stick the other probe into the connector for the IGN terminal of the VR. Again you want to see a very low reading. Over .3V or so (3/10) is too much, and indicates a voltage drop from the battery, through the various connectors and ignition switch, to the regulator.
Thanks again for all the advice, have the car on jack stands working on the parking brake cables right now, battery disconnected. Looks like I will need a longer center cable to clear the dual exhaust...
PhillH
Well-Known Member
I went through this and even though it could be a million different things. Check to see if the ohm gauge pulses with it. Mine did. I cleaned the contact for the regulater since that grounds itself to the body. At the same time I replaced the battery ground strap, the strap coming from the front of engine to the radiator area and added one missing from the back of the head to the firewall. Problem solved. I got all that info from here, thank you very much.
I have one from a 111" wheelbase if needed, just the ride.
This information is worth repeating. You always have great electrical diagnosis info. tmm
I am doing something like that, I found the ground cable cracked at the battery terminal, pulled the voltage regulator, and cleaned up where it mounts, cleaned all ground wires at front of engine. I will look for the ground from wire from the back of engine to the firewall. Also did you notice that the regulator is transistorized? Thanks a bunch to all of you....
67Dart273
Well-Known Member
Yes, although this does not always exclude it as a problem
These problems CAN be difficult. You can get into sort of a low frequency oscillation. These things work on the same idea as feedback in a mike / public address system. The frequency is determined by the system and the situation. You notice that with mike feedback, moving the mike affects the tone, the amount, and so on.
These problems CAN be similar.
Here is where I am at with this. Just got the instrument panel back in and the fuel gage to work, car has a new electronic voltage regulator, had the alternator checked out, out of the car and it is supposed to ok. Did the amp gage by pass mod, and have an after market volt gage which bounces around with the light flicker.. Any help would be appreciated. Thanks....
Just fixed this on my 64. I have a new style regulator. One of the Brand new ones was causing a flicker at idle. Went away when the rpm's went up. I went ahead and added a couple of more grounding straps as well. Installed another new regulator and flicker went away. everything flickered on the car including the volt gauge. I swapped out the ammeter for a volt gauge.
67Dart273
Well-Known Member
So it's a repeating quite fast flicker?
You likely still have a voltage drop some place, or a "loop" formed causing a feedback.
One thing you might try is to "tap into" the regulator power wire as close as you can get such as where it all tee's together at the ballast, and jumper from there direct to battery with a clip. See if that temporarily makes things better.
It that does not do it, jumper a good ground direct from VR to battery, and if THAT doesn't clear it up try a different regulator. Pay attention to the connector make sure it's clean at tight, the VR connector that is.
Phreakish
Well-Known Member
I've seen this before when a diode or two popped in the alternator. Ac voltage causes the flicker. Rare, but happens.
A swap with a know good or remove it and have it tested, though I've seen bad alts pass the typical bench check.
It's also possible to disconnect the field and positive wire from the alt to see if it goes away - problem is that this test doesn't rule out the regulator. Alternator problems can be tough to diagnose.
A swap with a know good or remove it and have it tested, though I've seen bad alts pass the typical bench check.
It's also possible to disconnect the field and positive wire from the alt to see if it goes away - problem is that this test doesn't rule out the regulator. Alternator problems can be tough to diagnose.
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