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Topic: 2004 U320 dash volt meter dropping voltage (Read 459 times) previous topic - next topic

2004 U320 dash volt meter dropping voltage

  I have several questions from our first extended camping trip. On the trip, my dash gauge reading dropped down from the normal 13.5-14 to 11.5-12.00 volts.  At the same time the check engine alarm began to sound.  My generator was already running along with the Aqua hot.  After about an hour, with no voltage change, I switched the boost switch on and immediately the dash voltmeter bumped up to 13.5 again. What is causing this voltage drop?  Does my dash gauge only monitor the engine battery power?  Without the boost switch on, is my gen powering just the house batteries?

David Blackford

 

David and Barbara Blackford with Sadie          2004 U320 38 ft Tag axle "Big Blue"  2 slides          500 hp Cummins  w/ 2018 Jeep Sahara

Re: 2004 U320 dash volt meter dropping voltage

Reply #1 –
Quote from: dblackford –
1. 11.5-12.00 volts.  At the same time the check engine alarm began to sound. 
2.My generator was already running  After about an hour, with no voltage change, I switched the boost switch on and immediately the dash voltmeter bumped up to 13.5 again.
3. What is causing this voltage drop? 
4.Does my dash gauge only monitor the engine battery power? 
5. Without the boost switch on, is my gen powering just the house batteries?

David,
1. With that low of voltage you getting close to the ECM shutting down
2. I am surprised it ran that long before the engine at least started missing
3. Could be a bad connection on the alternator sense wire, a bad breaker on the sense wire, failing alternator, failing battery isolator. (first things that comes to mind)
3a. FYI research the DUVAC system that your coach came with.
4. Yes
5. yes.

Mike


Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: 2004 U320 dash volt meter dropping voltage

Reply #2 –
Check your alternator to see if it is putting out.
Peter and Frieda Morin
1999 36ft. U320 Foretravel
Build # 5436
1998 Suzuki Sidekick Sport

Re: 2004 U320 dash volt meter dropping voltage

Reply #3 –

My dash monitor does not read correctly.  When I read up on issues I have had with my gv320 I usually come across something one of the members have already figured out that is helpful to me. Someone suggested this item that I keep plugged in when running down the road.
Amazon.com: Palumma 24W/4.8A Dual USB Car Charger, 12V to USB Outlet with...

I have 2–12v plugs on the dash. My top one reads the voltage of the house batteries.
And the bottom plug reads the voltage of the chassis's batteries

As an Amazon Associate Foretravel Owners' Forum earns from qualifying purchases.

2000 GV320 4010 build #5712  2019-?
1999 Bounder 2000-2008
Bardstown, KY
🥃The Bourbon Capital of the World🥃

Re: 2004 U320 dash volt meter dropping voltage

Reply #4 –
Running the generator does not charge the start batteries as the coach was originally configured.  Switching on the boost switch connects the start batteries to the house batteries which makes your start battery voltage go up.

Start with a sense wire change, the connectors at either end fail. The sense wire lets the alternator know the start battery voltage. Test the output of the alternator.  A bad sense wire, bad connections, a failing diode based isolator and any of the connections from the alternator to the start batteries are suspect.  Check and clean every battery post and cable.  Make sure you batteries are connected properly.

Roger Engdahl and Susan Green
2001 U320 3610 #5879 (Home2) - 2014 Jeep Cherokee or 2018 F150
Hastings, MN

Re: 2004 U320 dash volt meter dropping voltage

Reply #5 –
Easiest place to start your troubleshooting is at the BATTERY ISOLATOR.

With engine at 1,100 or so RPM, check voltage on the middle stud (from alternator B+ terminal).  Should be in the high 14's.  Check voltage at the two outer terminals (one connected directly to chassis batteries, the other to the house batteries).  Each should read about .7 VDC less than the center stud.  13.5-14,2 is fine.

Let us know what you find and we can direct you to the "next easiest place to check".
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: 2004 U320 dash volt meter dropping voltage

Reply #6 –
 Thanks for all the responses and helpful direction. I now have a game plan ready. I will add to this post after I've made some checks.

Dblackford
David and Barbara Blackford with Sadie          2004 U320 38 ft Tag axle "Big Blue"  2 slides          500 hp Cummins  w/ 2018 Jeep Sahara