Engine running doesn't charge coach batteries

[walkervalj]

I own a 2006 Gulfstream Endura Super C, with 5500 Chev Kodiak chassis. Used to charge coach batteries when engine was running. No longer does. What do I look for first? I suspect a relay, or isolator, but do not have enough knowledge to know where to look. Owner manual says batteries charge when engine running, but gives no other info. Generator charges batteries, but truck engine does not. All 4 coach batteries are fairly new (less than a year). Shore power works fine. Have checked for any tripped breakers, and blown fuses, and have found none. Where is isolator located? What does it look like? . I have basic electrical knowledge and can run a VOM, but coach/chassis systems pretty new to me. There is a relay under hood labeled PTO. Any chance that is it? Any way to test relays ? Any help appreciated

[donc6288]

I have a 2004 Crescendo with the same issue. All fuses are good that I can find. At the IRD or isolator relay delay, the battery terminal is hot, but with the motor running, neither the solenoid or the ignition terminals have power on them.

[eddard]

It may be different in the newer models, but on my 1998 Gulf stream Ultra, the isolator solenoid is mounted in the engine compartment on the firewall just right of center. the coach battery lead is clearly labeled, the engine (chassis) lead is not. Using a multimeter, you can test for an energizing signal by probing the terminals on the solenoid. If the triggering voltage is there, it would appear that your solenoid has failed.

As a temporary fix, you could put a fused jumper from one side of the solenoid to the other. I made one years ago for my old MH, using 12 gauge wire, a 10 amp fuse, and alligator clips.