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Topic: No charging voltage  (Read 351 times) previous topic - next topic

No charging voltage

I just got done changing the hose between water  pump and Thermostat housing.
I had to take the alternator off


I put everything back together and after I started the engine the voltage on my gauge does not show the higher 13.8 charging voltage and its the same when I run the generator.
I use a simple voltage reader  that I plug in the cig lighter plug and it reads the same in both cig light sockets.

normally  when driving I would see 13.8 voltage and when stopped would be around 12.8.


how do I proceed  here.

check the output at the alternator

then check the boost switch

check the vsr


2003 Foretravel u320 build 6066
cummins 450 ism
2008 Jeep Cherokee Toad
former Country Coach Owner.
Part time Rv er
Never afraid to learn.

Re: No charging voltage

Reply #1 –
Quote from: danilaprepeleac –
I had to take the alternator off...
I put everything back together and after I started the engine the voltage on my gauge does not show the higher 13.8 charging voltage

how do I proceed  here.
check the output at the alternator
then check the boost switch
check the vsr
When a "problem" pops up immediately after working on the engine, the last thing you messed with is the first thing to check.  So yes, take a good look at the alternator.  Did you reconnect the wires to the alternator exactly as you found them before removal?  How many wires connect to your alternator?  You should have the large positive and negative cables, plus either one or two small gauge wires.

If you are sure the wires on the alternator are correct, then run the engine at high idle (about 1000 rpm) and check the output voltage at the large B+ post on the alternator.

The BOOST switch has nothing to do with the alternator charging output.  All it does is physically connect the two battery banks.

VSR (Voltage Sensitive Relay).  Do you have a battery isolator on your coach, or does the VSR take the place of the isolator?

1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: No charging voltage

Reply #2 –
Yup, #1 suspect is that the alternator connections are not correct-- either on wrong post or not clean and tight.
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: No charging voltage

Reply #3 –
Unfortunately, based on my experiences, now try ONLY ONE THING at a time. Changing too many connections at once can quickly complicate the hell out of things.
Change one thing then check.
Nitehawk,  Demolition Lady, & our NEW master, Zippy the speeding BB cat.
1989 Grand Villa 36' ORED
Oshkosh chassis, 8.2 DD V8
2006 Saturn Vue AWD

Re: No charging voltage

Reply #4 –
What nitehawk said. What does the voltage gauge on the dash read with the engine running?
1993 U225 Build #: 4285
500 Watts Solar
Honda CRV AWD
Former 1981 Foretravel Travco
Retired, Full Time Off Grid Snowbird