Maybe this has been covered but as I am new I have not seen it.
Just lately the gauge on the dash for volts is now upon starting, fluctuating between just under 12 to about 13.5, back and forth for a few minutes and then stays at 13.5 (or whatever it needs depending on state of batteries). I can drive for hours with no change once it settles down to normal, but then stop engine and start again and we go thru' the same pattern. I am sure someone has ideas on what is happening and what I have to do.
Thanks John
John, I can tell you with confidence that it is probably a bad ground. I just went through the same scenario. After 3 months of checking things, it was just a dirty battery ground. First step is to clean the starting batteries. If that doesn't fix it then check the chassis grounds before testing the alternator.
I had a somewhat similar problem that turned out to be intermittent making/breaking of the 6 amp circuit breaker that sends excitation to the alternator. This breaker is located with many of the other automotive breakers behind the cover in the stairwell.
I am going to out on limb and guess something that it might be. I had several Dodge trucks with Cummins diesels over the past several years. When I started them in cold weather the intake heater would come on and off for several minutes until the engine warmed up a bit. Usually just a few minutes. It would cause the volt meter to fluctuate as it would draw amps for the intake heater. I dont know if these engines work similarly. I guess someone will chime in on my guess.
Regards, Mark
thanks for these suggestions. I will check each possibility out once I get the coach back from getting new windscreen and a scratch fixed
John
You should have glow plugs on your coach. It s why they say not to use ether in there among other reasons. It does draw a bit of current. The M 11 has no Glow screen so they put an ether bottle in line for you. Strong batteries and a good starter and an update to the ECM took care of my hard start issue when it was cold out.