Goofy headlight problem

[sargentwolf]

Hi all.

So finished up installing my new backup camera today. Works great, I can now see the confused drivers behind me.

Problem I've been having (and it's been beating my best troubleshooting methods) is the electrical gauge bounces between 20 and 26 volts while idle and there's nasty alternator whine over the intercom headsets.

When I turned on the lights, I had accidentally turned the high beams on. The bouncing volt gauge was gone, it was steady at 26 volts. Looks like the issue is there.

Now, what makes the circuit different when the high beams are on? More voltage? Guessing I have a grounding issue inside the headlight buckets and the increased voltage powers through the ground?

Guesses?

 

[coachgeo]

Headlight switch issue?

 

[tennmogger]

My truck did that, bouncing volt meter, voltage steadies with load. That went on for months. Then the truck would not start one day. Batteries were bad, the 12-24 pair, showing high internal resistance. New batteries fixed the voltage fluxuation completely.

There was not sufficient load on the alternator. The bat cells would come up to regulator's upper limit v, the alt would drop voltage, see 'too low' and charge again, hit limit, on and on.

Try load testing your batteries, individually.

As bad as my batteries were, I don't know how it had started every time! But the engine starts on first click so batteries had juice for that. That's why a heavy load test is needed.

 

[sargentwolf]

I'll ohm out the switch.

Can't be, had em checked 2 months ago. All are good.

 

[gimpyrobb]

All were good.

I have found a carbon pile tester to be a great tool to have in the stable.

If not batteries, my next guess would be voltage regulator.

 

[Awesomeness]

I would think that what changes when you turn on the high beam headlights is that you actually start putting a load on the alternator/voltage regulator. The high beams are probably the highest current drawing device in the truck.

Try this simple test. Start the truck, watch the bouncing voltage gauge, then connect some high-current device to the voltage posts in the dash. It doesn't really matter what the device is - you could use another headlight, or maybe a 24v power tool, etc. See if the voltage gauge stops bouncing. You may also need to try both a 12V and 24V device, separately. If the gauge stops bouncing, it's something in the charging system, most likely the regulator I would think.

 

[coachgeo]

I would think that what changes when you turn on the high beam headlights is that you actually start putting a load on the alternator/voltage regulator. The high beams are probably the highest current drawing device in the truck.

Try this simple test. Start the truck, watch the bouncing voltage gauge, then connect some high-current device to the voltage posts in the dash. It doesn't really matter what the device is - you could use another headlight, or maybe a 24v power tool, etc. See if the voltage gauge stops bouncing. You may also need to try both a 12V and 24V device, separately. If the gauge stops bouncing, it's something in the charging system, most likely the regulator I would think.

Headlights are 12v so would assume this test to work best at the 12v lug in the panel.

 

[Suprman]

I would remove the AC connection on the regulator and tape it off. Run the 24V regulation wire to the fuel solenoid positive, remove the old one and tape off. See if that helps.

 

[sargentwolf]

Ok so an update.

Now the gauge is steady no matter what I do. Lights on/off, high beam on/off, CB intercom and camera on/off...I have not done the regulation wire trick yet, it just fixed itself.

I blame aliens. Or a loose ground somewhere. There goes my weekend...