Headlights Flicker on 2005 Roadtrek 190 Despite New Batteries and Alternator

[apiufb30]

Question: My headlights are fluctuating dim and bright when I turn my van on. The battery gage on the dashboard also fluctuates. I have replaced the engine battery and the alternator, and now the coach battery. I didn't realize I was supposed to switch the inverter/converter/charger to "off" or "charge only." So it has been on "auto" this whole time (18months). My engine battery died about four months ago, so I had it replaced. I noticed the headlights fluctuating so I had Autozone test the engine battery and it said it was bad. So they replaced it, under warranty. I turned the inverter/converter,charger to "off." Then they tested the alternator and said it was bad, so I replaced the alternator three days ago. I went back to Autozone because it didn't fix the headlight issue. They checked the new battery and it was at 7%. So we put another new battery in. Then we check the coach battery and it read 6 on the multimeter. So we replaced the it with a new coach battery. This still hasn't fixed the headlight situation. But it did help with the interior lights. So I'm wondering if my isolator isn't working correctly? Or could it be my self resetting circuit breakers? Has anyone ever heard of this problem?

 

[youngnretired]

A couple questions: are just the headlights fluctuating, or also the interior lights, and does it fluctuate with the ignition key off (i realize the headlights dont come on with the key off or out of gear), turned on, or running, or all 3? For the headlights, is it fluctuating with only the low beams on, and have you verified that the high beams are or are not intermittently turning on/off?

Wondering if its a voltage regular/electrical connection issue, or something like a bad headlight switch.

 

[apiufb30]

The headlights, dash lights and battery gauge on dashboard fluctuate when I turn the van on. As it idles, they fluctuate, and they do the same when driving. The interior lights used to fluctuate as well until I replaced the house battery. Now the interior lights work perfect. The high beams work but they also fluctuate dim/bright. It also doesn't seem to correlate with revving the engine at all. I also just checked the ground wires and isolator wires and everything seems to be nice and tight. Pulled out the headlights and checked connections, all good there. Pulled the fuses out to the head lights and they look fine. I did notice this wire in the picture is hanging free. It looks like it goes to that spring loaded bolt at the top left. Not sure what that is? I traced it, it's a blue wire that runs to the interior of the van under the driver side dash.

 

[TX-Trek]

Have you checked (cleaned) all grounds?

 

[apiufb30]

I checked the grounds, they were tight and didn't look corroded.

 

[youngnretired]

Im not familiar with the isolator systems on these RVs as we bought our first one less than a year ago.

When the key is on or van running, is there voltage on that wire? It also looks like it rusted and the end broke off, see if you can find where it could have been attached to. Is there continuity between it and ground?

Also, and this has nothing to do with this being an RV, but lights that fluctuate seems like a voltage regulation or load issue. Assuming a high amp load doesn't exist on your camper and that the voltage regulator has been replaced because its inside the alternator, see if the big huge fat bare electrical bonding wire is tightly connected between the engine and the chassis or if its loose or missing. I do not know where these normally are on a newer van or 6.0L engine, but on older chevy stuff, it was always on the back of the engine to firewall. If this is disconnected, loose or missing, your voltage regulator may be "floating" as it does have a solid ground reference to know where its voltage output actually is.

There may be the negative wire from the battery down to the engine, but the battery, engine, and chassis all have to be bonded electrically for things to work properly.

 

[apiufb30]

Okay I'll give that a look. Thank you

 

[bwiencek]

I checked the grounds, they were tight and didn't look corroded.

Best to clean the ground on BOTH ends (chassis and battery) and then check and replace or double up the ground strap between engine and chassis as I believe it's the braided style and they are prone to getting corrosion and high resistance. (Google search the year and model (2005 chevrolet express 3500 ground locations) to find reference to where all the grounds are located so you can check and clean them (even if they look ok - clean them).

Once you do all that check voltage drop between - post on battery and engine block, chassis, and terminal on headlights. I'm going to guess like the others that your bonding between chassis (load and isolator), engine (alternator) and battery isn't good and there is resistance somewhere in the circuit causing your issues. The alternator could have either not been working or even fried because of the high resistance and the isolator could also be having issues because of grounding issues too.

 

[Hatteras Jim]

I agree it sounds like a ground/connection problem. Sometimes a layer of oxide builds up on the battery clamps on the inside. Make sure they are clean and bright. If they are good, try to find an old analog voltmeter and check the output directly on the alternator and battery to see if you can actually see the voltage fluctuations. Sometimes you can't pick this up on a digital meter. Your alternator (if the regulator is built in) could be failing. If you can't find the issue, then I would suggest an electrical shop. If the alternator spikes while you are driving, you could lose all of your bulbs at once. Isolators, which are just high current diodes can produce weird symptoms when going bad. There is a voltage drop across them of 0.6 to 0.9 volts when operating correctly.

 

[ccourcier@gmail.com]

Question: My headlights are fluctuating dim and bright when I turn my van on. The battery gage on the dashboard also fluctuates. I have replaced the engine battery and the alternator, and now the coach battery. I didn't realize I was supposed to switch the inverter/converter/charger to "off" or "charge only." So it has been on "auto" this whole time (18months). My engine battery died about four months ago, so I had it replaced. I noticed the headlights fluctuating so I had Autozone test the engine battery and it said it was bad. So they replaced it, under warranty. I turned the inverter/converter,charger to "off." Then they tested the alternator and said it was bad, so I replaced the alternator three days ago. I went back to Autozone because it didn't fix the headlight issue. They checked the new battery and it was at 7%. So we put another new battery in. Then we check the coach battery and it read 6 on the multimeter. So we replaced the it with a new coach battery. This still hasn't fixed the headlight situation. But it did help with the interior lights. So I'm wondering if my isolator isn't working correctly? Or could it be my self resetting circuit breakers? Has anyone ever heard of this problem?

You might be having a computer problem. The alternator voltage regulator is in the computer (ECM/PCM). Replacing the alternator wouldn't fix that.
When the alternator is charging it makes a very slight whistling noise. If the voltage regulator is switching the alternator on and off... if you listen closely you should be able to hear the whistling going on and off (unless there's a lot of ambient noise).
There might also be high resistance between the alternator and the battery causing the computer to get a faulty reading.
A shop with a good scanner should be able to diagnose that.