RV Trip Planning Discussions

Go Back   iRV2 Forums > THE CHASSIS CLUB FORUMS > Freightliner Motorhome Chassis Forum
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
Thread Tools Search this Thread Display Modes
Old 03-19-2019, 07:29 PM   #1
Senior Member
GaDawgFan's Avatar
Join Date: Mar 2007
Location: Dacula, Georgia
Posts: 309
Alternator question

I have a 2000 Itasca Horizon on Freightliner chassis with Cat 300. While on the road last week I noticed the volt meter gauge was all over the place. Dropping al the way to the left and then back to the normal range. I have a Scanguage D on the dash and could see the volt gauge fluctuating between 11 & 13.5 volts. Am I same to say that the alternator needs a rebuild?

2000 Itasca Horizon 36LD

300 HP Cat Diesel
GaDawgFan is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 03-19-2019, 08:27 PM   #2
Senior Member
cataska's Avatar
Join Date: Jan 2018
Location: Sacramento CA.
Posts: 242
May be loose connection/bad ground I would check connections.

2005 Itasca meridian
cataska is offline   Reply With Quote
Old 03-20-2019, 12:42 AM   #3
Senior Member
FIRE UP's Avatar

Join Date: Dec 2009
Location: Out there, somewhere
Posts: 7,957
How about the belt? Maybe it's loose. But, I'm not all that familiar with the 3126 version of the CAT like I am with the C-7 version. In the later one, like ours, it has a spring tension serpentine belt that spins that alternator so, I'm not sure on yours. Could be loose connections on the back of the alternator too. Let us know what you find.
2004 ITASCA HORIZON 36GD, 2011 GMC Sierra 1500 4x4 Toad '08 GL 1800 Gold Wing
Retired-29.5 yrs, SDFD, Ham - KI6OND
Me, Karla and the Sophie character, (mini Schnauzer)
FIRE UP is offline   Reply With Quote
Old 03-20-2019, 12:39 PM   #4
Senior Member
Rkesselus's Avatar
Tiffin Owners Club
Join Date: Aug 2016
Location: Bastrop Texas
Posts: 1,104
3126 has a separate belt for the water pump all else runs off the serpentine belt
2000 Allegro Bus 35R 3126 Cat 300 Allison 3060MD 6 speed
Rkesselus is offline   Reply With Quote
Old 04-08-2019, 10:23 PM   #5
Senior Member
Join Date: Jun 2016
Location: Nine Mile Falls WA / Arizona City AZ
Posts: 993
In almost all cases, alternators are built to run the life of the engine.... but sometimes the brushes wear more quickly than others.... In all the HD units I've had apart, its always been brushes worn down to the spring.... new brushes.... all's well... that's where I'd go first...
Retired Business Owner, Re-manufacturing HD Clutches, Brake Shoes, Air Compressors, Sales & Installation of PacBrake and other Industrial Friction
jelag is offline   Reply With Quote
Old 04-09-2019, 09:47 AM   #6
Senior Member
mevman's Avatar
Fleetwood Owners Club
Freightliner Owners Club
Join Date: Feb 2012
Location: North Little Rock, Arkansas
Posts: 440
Originally Posted by jelag View Post
In almost all cases, alternators are built to run the life of the engine.... .
Interesting observations. I have had 2 separate alternators lockup due to bearing seizure.
2008 Fleetwood Bounder 38S w/Cummins 6.7 ISB, Flat tow-2010 Ford Ranger
Rich (KG5JAQ/WRDN699) & Margaret, Shih-Tzu 'Charley' in avatar.
mevman is offline   Reply With Quote
Old 04-09-2019, 10:35 AM   #7
Senior Member
Skip426's Avatar

Join Date: Apr 2011
Location: Powell River, B.C.
Posts: 18,532
I had similar issues last year ; the A/C compressor clutch bearing was failing , binding and causing the serpentine belt to slip ( then finally break ) volt reading was erratic prior to the belt breaking.

Easy enough to check ; remove serpentine belt and spin alternator , A/C clutch hub, and all related bearings in the belt routing.

A second thought; I always have them .

Is it possible that the outside temp was low enough that the engine's intake manifold heater was cycling , or was the engine at full operating temp ??
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.
Skip426 is offline   Reply With Quote
Old 04-09-2019, 11:35 AM   #8
Senior Member
Join Date: Jul 2014
Posts: 20,190
I think inactivity may be why MH alternators seize.

I don't recall seeing any seized alternator bearing, in 35 years of heavy equipment repairs.

In my experience, dirt was the killer, and even then, most were pretty hardy.

Leese Neville, on Cummins powered wheel loaders, was the one we replaced more often.
twinboat is online now   Reply With Quote
Old 04-09-2019, 12:48 PM   #9
Senior Member
bob caldwell's Avatar

Join Date: May 2017
Location: Vancouver Wash
Posts: 5,655
Voltmeters get their power from any circuit that's hot with the key on......
2010 Rockwood Sig Ultra lite 5er 8280......'99 Ram 2500, Cummins. 4x4.....Pullrite Superglide.......Use to work in calender factory.....got fired for tak'n a few days off.....RV Mutant 186
bob caldwell is offline   Reply With Quote
Old 04-09-2019, 01:39 PM   #10
Senior Member
Skip426's Avatar

Join Date: Apr 2011
Location: Powell River, B.C.
Posts: 18,532
A third thought .

Did the battery light come on when the gauge dropped to the bottom of the scale ?

Testing info on the gauge system in this file .
Attached Files
File Type: pdf Freightliner gauges operation , testing.pdf (127.9 KB, 25 views)

99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.
Skip426 is offline   Reply With Quote


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Alternator belt and alternator replacement jimloeh Monaco Owner's Forum 7 08-15-2016 05:10 PM
Alternator question on 2001 Alpine 4day Alpine Coach Owner's Forum 4 07-05-2014 08:49 AM
Alternator question BushlandGS Cummins Engines 6 08-16-2011 05:01 PM
Alternator question prpickett Newmar Owner's Forum 16 05-29-2011 07:26 PM
Alternator Light stays on but alternator charges augiedeg Spartan Motorhome Chassis Forum 1 10-20-2010 07:05 AM

» Featured Campgrounds

Reviews provided by

Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 11:21 AM.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2020, vBulletin Solutions, Inc.