Headlights go out and then later come back on

[gumpy]

Not due to 50 watt bulbs. Those were standard, I think, and at 28v, that's only about 2 amps each.

Ok, here's a question for you. Are your fog lamps on a separate circuit, or are they factory wired? The schematic shows a fog/head light switch where either the fog lights are on
or the headlights are on. is that how your bus is?  or can the fog lamps and head lamps be on together?

[Brett G]

They can be on together.  The 2 times when the headlights went out, I drove with the fog lights on and then the headlights would come back on....so they were all on. 

Brett

[Brett G]

I can test to make sure again.

[gumpy]

Ok, so it's probably the 15A circuit breaker off terminal 14 that feeds the headlight circuit that is tripping. The problem could be a weak breaker. You could try
swapping in another one of similar rating just to see. I doubt it's the breaker, though. It's more likely a short in the switch or the dimmer switch. Could also be
in the relay, but usually wouldn't cause a breaker to trip. Just wouldn't work.


Check your wiring starting at stud 14. follow the circuit path. The wiring should follow. Look for something that might be shorting a terminal to ground or something else.
Check the switch to make sure it's functioning properly. Might need to pull the wiring and use an ohm meter on the terminals. Same with the dimmer switch.

Dimmer switch would be my first suspect. They're usually metal cased, so if something internal breaks or comes loose, they can easily touch the grounded case and
cause the short. Stomping on it several times could have broken the contact, and when the circuit breaker cooled, it turned back on. maybe it's just a loose wire on the
dimmer switch connection or on the headlight switch connection.

[Brett G]

This is good stuff.  I'll get after it.  I re-read your earlier post.  The original lights must have come with 50 Watt bulbs but that's not what's in there now.  One is a 90 Watt.

Wagner 28v 4579 80/60W and the other is a Wagner 28v 4813 90W

[gumpy]

Well, they are a bit higher in wattage, but not significant enough to cause a problem. The circuit is fed through a 15 amp breaker and then split between
high and low 10 amp breakers. If both high and low are going out, then the 15 amp breaker is the one that's tripping, so the problem lies either in that
breaker or between that breaker and the 10 amp pair.

[Brett G]

I plan on tackling this, this weekend.  With the current bulbs (Wagner 28v 4579 80/60W and the other is a Wagner 28v 4813 90W) and if my math is correct, when the high beams are on, it's drawing 14.2 amps and that breaker is 15A.  Think that's too close, especially with breaker being that old?  Other thought is that I'd like to keep the current lights because they arebpretty darn good at night.  Can I replace that 15A breaker with a 20A breaker?   80W x 2 + 90W x 2 = 340 / 24 = 14.2 amps

[gumpy]

it's possible. Your voltage should be around 28V when your bus is running which drops the current to around 12.5.

You could probably change that breaker. It could be weak.

You could increase it's size, too, but you need to see what size wire was used (I can't read it in the schematic).  If the wire is not large enough,
you'll have to run new wire for the circuit. 12ga would be a minimum and if you have to come from the batteries, then 10ga to the junction box
and 12ga from there on.  If you change to a bigger breaker, use one that is self resetting. You've already seen why :-)

[eddiepotts]

Just a suggestion but check the ground wire on your head lights. if your ground is not heavy enough from the wire strands getting and broken from age and vibration you will pull a heavier load. this will trip the breaker. With the lights on for awhile feel the ground wire with your hand and see if it is hot.

[zubzub]

I have had this problem in a 12 volt system it was worn out wires....headlights pull some amps for a long time.  changed out the wire was not the first person to have done so on this bus....so I used larger wire.  Don"t know about your bus but mine only runs on high or low not both at same time....agree that floor mounted dimmer switch is usually the first place to look.....easy to replace and they almost always need replacing as most are garbage.

[Brett G]

Thanks all, I'm waiting on a circuit breaker to come in and then I'll start diving in.

[bevans6]

He has a four headlight system so on high beam all four lights are on.

Brian