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Topic: E-450, new alternator it test good, not charging battery.. (Read 285 times) previous topic - next topic
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E-450, new alternator it test good, not charging battery..
Any ideas? 2002 31B LD.

Thanks,
Mark
2002 30' IB
Need electrical schematic for 2002 31B LD
Reply #1 –
Does anyone have a electrical schematic for 2002 31B LD?
2002 30' IB
Need electrical schematic for 2002 31B LD
Reply #2 –
Does anyone have a electrical schematic for 2002 31B LD?
2002 30' IB
Re: Need electrical schematic for 2002 31B LD
Reply #3 –
There is no such thing.
Don & Dorothy
Sold our LD in June of 2023

Our boring always non-PC travel blog
Traveling Dorothy
Re: Need electrical schematic for 2002 31B LD
Reply #4 –
Can you tell me if there is a fuse for the alternator?
2002 30' IB
Re: E-450, new alternator it test good, not charging battery..
Reply #5 –
Mark-

Not charging the chassis battery, the house batteries, or both?

I assume if you're asking this question that you did not install the new alternator yourself. If so, then what does the person who installed it say about it not charging the chassis battery? I should think that was a functional check he would have made.

Check your owners manual. It likely has a diagram of the alternator/charging circuit. On coaches old enough to have a diode isolator installed, the alternator output cable goes to the center post on the isolator. The chassis battery 12V+ lead goes to one of the isolator output posts, and the house battery bank to the other output post. I believe later coaches used a solenoid, rather than a diode isolator. As I said, look in your manual.

Mark H
Former owner, 31-foot gas Class A
Former owner, 1997-8 mid-bath
Re: Need electrical schematic for 2002 31B LD
Reply #6 –
I am not a tech.  There well might be a fuse for the alternator. Anything under the hood is Ford, not LD. Your Ford owners manual will show the location of each fuse. There is a box under the hood and also one under the dash. I hope you got both the Ford and LD manuals with your rig.

You did not say which battery is not being charged. If it's not charging the chassis battery, go back to where you had it installed. You can test if the voltage is reaching the house batteries with a VOM. Anything reading over 13 indicates voltage is reaching them. 14.2 would be about right. If you don't get a reading, you may need a tech. Good luck with that. most know less than I do.

Charging the house batteries with the alternator is a slow process.
Don & Dorothy
Sold our LD in June of 2023

Our boring always non-PC travel blog
Traveling Dorothy
Re: E-450, new alternator it test good, not charging battery..
Reply #7 –
The alternator is protected by a fusable link.
It's a short section of calibrated wire, normally 4-gauge sizes smaller than than the wire it is protecting.
If it burns out, it needs to be cut out and then have a new usable link splice in.
If the alternator is protecting  good power, chance are the isolator had failed.
With the engine running, check all three terminals of the isolator for voltage.
You should see readings in the 13-volt range, on all three terminals.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: E-450, new alternator it test good, not charging battery..
Reply #8 –
Did you mean fusible link, Larry?
Greg & Victoria
2017 Mid-Bath  “Nocona” towing a manual 2015 Forester
Previously a 1985 TK
SKP #61264
Re: E-450, new alternator it test good, not charging battery..
Reply #9 –
Larry means a fusable link. 
Ford put the big one at the starter solenoid end of alternator output/ ammeter shunt cable in 1991. 
 LD may have relocated it to accommodate the battery isolator.

My  1991Coachman Van was electrically dead whhen that one melted, well blew,  Not even the 4 way flashers would work.  Cause,  the alternator diode board disentgrated shorting the battery to ground.
Rodney
1988 Mid Bath
Re: E-450, new alternator it test good, not charging battery..
Reply #10 –
Thanks for the great advise. We will be rechecking the system Monday.
Electrical issues can be the most frustrating and difficult problems to solve.


Mark.
I will be ordering an owner's manual next week.
2002 30' IB
 
Re: E-450, new alternator it test good, not charging battery..
Reply #11 –
Mark-

The Ford EVTM (Electrical and Vacuum Troubleshooting Manual) went with the LD when we sold it a couple years ago. They are specific to the model year of the chassis. You can pick them up on eBay for not a lot of money. The EVTM covers all the Ford wiring, including the ignition and chassis battery charging systems.

Here's the diagram from the 1997 LD manual. It covers the connections to the diode isolator and from there to the house batteries.

Mark H





Former owner, 31-foot gas Class A
Former owner, 1997-8 mid-bath