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Robwheeler · 04-02-2021, 11:05 PM

Ok all. Thanks for your replies and I am still searching. Here’s what I’ve found thus far as i continue searching.
Ground wire to chassis battery never connected correctly by previous owner. Repaired.
Installed new isolator/aux start solenoid. still no charge for chassis battery, but when I drive I can now push the button and charge from house batteries while driving which is new and exciting😂House batteries charges fine from shore power and I jump them to charge chassis battery while on shore power.
Checked new alternator and it wasn’t putting out voltage. Checked fuses and found blown fuses. Replaced blown fuses and alternator began charging for a minute, followed by a “burning”smell. Shut down, checked all fuses and “gauges” fuse was blown and alternator shows no charge again. I’m convinced I’m now chasing a short, but could use advise on where to start. I’m going to replace gauges fuse tomorrow to seee if alternator fires up again.
I’ve never run into an alternator that won’t charge without a fuse and it’s baffling me. Is it my “l” wire, smallest on the alternator, telling it not to charge?
Confused!!!
Thanks

YC1 · 04-03-2021, 08:33 AM

What fuses are blown and what size are they? Pictures please please.

If your batteries have been charged up and are in good working order the alternator should not be working hard.

However, with the vintage of the rv/engine I would be looking closely at any engine block ground straps to the frame. Those need to be working correctly or other wires will suffer the pain.

Use your nose and find that smoke. It is really hard to get it back into the wires.

The fuse blew for a reason if you smelled smoke. You might be lucky and just need to get the wiring cleaned up.

You CANNOT have any resistance in connections when messing with a high current device like an alternator or battery. Twelve volts just will not push through any contamination.

A dremel tool with a sanding drum is fantastic for cleaning things up nice and shiny.

Once you are positive your grounds on your batteries and engine are solid as new then replace the fuse with a smaller one if possible to start. If it pops immediately don't panic, you can move up in size until you reach the factory sized one.

Does your rv have a external regulator? A nice shiny box (when new), mounted somewhere near the engine. It likely has wires marked with information. If so, just replace it after taking careful pictures and disconnecting all batteries. If you replaced an alternator with an external regulator and did not replace the regulator you did just half the job. My opinion of course but the alternator is the heartbeat of the 12 volt systems.

Robwheeler · 04-14-2021, 11:44 PM

Thanks for all the trouble shooting advise. I realized that fuse marked gauges is actually all the indicator lights on the instrument cluster. Upon turning the key to on, the park brake, temp, seatbelt, check engine lights would illuminate for a few seconds, then pop the 20 amp fuse under the dash. I also traced when this happened, the ISO relay ignition fuse 5 amp on the firewall under the hood would pop. I decided to pull the fuse block on the firewall to check for an arc or similar. I didn’t see anything but cleaned up the connections and put the block back on. I then went inside and tried to check all systems tied to the indicator lights. Anything I could see like the wire to the parking brake sensor, an engine temp sensor, seat belt sensor, I’m not exactly sure if I found any of them but low and behold and I’ll quote my wife “ I did some great wire jiggling”. The 20 amp fuse is not popping and the alternator is charging. Of course I’m more confused than ever, since I should have stopped at every wire I checked and turned the key on but I wasn’t that smart. Right now I’m leaning towards the fuse block on the firewall because they looked a little crammed in there and there is probably 1/8 inch between the rear of the connectors and the steel it’s mounted to. I will continue on but as of now I’m much closer than I was. Thanks for all your help so far

Robwheeler · 04-14-2021, 11:49 PM

A side note, when these symptoms occur and the fuse is blown and I turn the headlights on with the key in the on position I get the warning chime that you would normally get when the headlights are on and the key is off. Im trying to make sure that the headlight switch isn’t also causing the fuse to blow as there are about 8 wires coming to and from that sucker too .

donr103 · 04-16-2021, 08:31 AM

if you look just above the fuse box in the picts. there will be a small black box. maybe 2in by 3in and 1/2 thick . it is very hard to see or find. that is the isolator. i found if you blow or brush off top and get cell phone in there you should find the part number on the top . web check it and down load diagram. The AUX START RELAY is a bad name for what it does. it should be aux start/coach bat charge relay. the isolator will charge coach batts when it sees that chassis bat above certain volts. I am glade you got problem fixed but how old are your coach batts and have any one been in there moving things around.?? my point is.. that if you got bad coach batt or short then you could over load chassis alt and blow fuses. also seach here battery isolator and you will find people here that know far more than me. I also would like to thank this site and the community for helping me. I know they will help you get to the bottom of this. good luck

donr103 · 04-16-2021, 08:39 AM

just a note look up battery combiner too. the MH charges all batts going down road but on shore power only charges coach batts on different mds so your chassis batt will not charge on shore power, i added one now i charge chassis bat and coach batts on shore power. i still think you might have a problem in coach batt side. or just luckly fixed it.. i got this info here. just search batt combiner.

Robwheeler · 04-16-2021, 10:38 PM

You guys have helped me a lot and thanks for so much information.
I got the gauges fuse to not blow when I turn the key on by shutting everything down first. I fire up the truck and have alternator voltage and everything’s great ��.
I take it for a test spin to pump out and get her warmed up. I’m pushing over 14 volts the whole time and start turning one thing at a time and never drop below 13.5 until I turn on the heater. Fuse blows and I get no amps out of alternator. ��. Guess which fuse doesn’t blow when I start checking everything out? The fuse marked heater. ��. Shut heater off pop in new gauges fuse and she’s charging again. I shall now tear into the heater and find out why. So far I see power to the fan switch, so I assume I’ll find 7 more relays or a burned heater/blower fan shorting out.
So happy to at least I know I can get a charge from the alt!!!
Thanks again

YC1 · 04-17-2021, 07:52 AM

It sounds like something is miswired.

Since the previous owner did not connect the ground from your chassis battery it could have done some serious damage.

The battery path will try to find a way for those massive electrons to flow when starting but you could have been spared by having to use the aux start button thus actually using the coach batteries.

Getting close to 14 volts from the alternator is a positive thing. Why it is NOT charging the batteries ??? is a problem.

It might be time to step back and post a list of issues fresh. What fuses are popping? What voltages do you have on that fuse block that was "missing" voltage.

I doubt your heater fan is bad because they take a lot of current and adding that bit to a miswired circuit could pop a 20 amp fuse.

You might consider finding the fan wire and connect your own power temporarily through an inline fuse. If you have a clamp on ammeter you could simply measure the current and post that.

I mentioned earlier that you might be able to run the generator, push the aux start button and charge your engine batteries. This is a temporary workaround when in trouble but seems to work for many folks.

Since your vehicle has been "rewired" to some degree it could be impossible to sort out without a real schematic for the vehicle. Finding the amount of power the heater is using (assuming it is not bad), would allow you to use your own inline fuse holder and just bypass any issues.

donr103 · 04-17-2021, 09:07 PM

if i were you i would disconnect bats and go down to starter and make sure the wires at the starter are very clean. take picts first how connected. then check each fusable link there. and next would be the computer or ecm it tells the alt when and how much to charge.. i have ran into that problem before