battery isolator/disconect

[rwquick]

1995 gulfstream sunvoyager. The battery disconect in the stairwell for the chassy will not turn off.
Started 3 day's ago while driving the defrost fan quit working. When we got home I pulled the fan and tested it, it was good put it back in. tried to start the rv but the battery disconect in the stairwell would not turn on. Thought I had dead batteries put a charger on it, the charger said the batteries were good. Put the charger on quickstart and was able to turn on the isolator in the stairwell and start the rig. Had a red light for an overheating transmition (we did not drive it anywhere) which would not go out. the defrost fan worked. Shut the rig down and tried to turn off the chassy battery, it wont turn off. Started the coach the next day and the red light is out, stil lcan't turn off the chassy batteries.

Need advice on where to begin.

also plan to replace the thermostat on the cummings diesel. Which hose has the thermostat behind it the top or bottom. What is the normal operating temperature of a diesel engine

[Wanabee FTer]

Hi rwquick, Welcome to IRV2!

I would start by checking for loose/poor ground connections. There are many throughout the chassis, check the battery connections and ground connections first then clean and tighten any other ground connections if needed.
Good luck and keep us posted.

[trower]

The thermostat is going to be near the top of the engine close to the water pump. May or may not be at the upper hose connection. Most diesels operate at nearly the same temps as a gas engine. 180+- normal driving and 210-220+- at load. The exact temp is controlled by the Thermostat setting 160, 180, 190 etc.

[KIX]

My engine coolant runs at about 175* F.
In an engine (gas or diesel) the thermostat does not control the temp. It will stay closed until it reaches the design temp. And then stay open until the engine coolant cools down at shut down. It doesn't open and close to help maintain temp.