mackandmaggie Report post Posted March 22, 2023 My 2017 Newmar with 6.9 cummins voltmeter fluctuates at startup about 10-12 times, then settles down to 13+ volts. This started a few months ago. Bought 2 new chassis batteries , cleaned and tightend all connections, and it still continues. Does anyone else have this issue. The rv runs great 14k miles. Don't know if is alternator voltage regulator. 40 miles from cummins office Share this post Link to post Share on other sites
dons2346 Report post Posted March 22, 2023 Welcome to the forum Mack. Are you now in a colder climate? It is possible that your intake grid heater is cycling on and off to adjust for the colder climate. It is also possible that the timer is failing. Doubt seriously that you have a failing alternator Share this post Link to post Share on other sites
bhalldorson Report post Posted March 22, 2023 I have a 6.7 cummins in a 2008 Fleetwood and it has always done this. We bought new and it never presented a problem so I haven't investigated. Fluctuation seems to last longer if it has been sitting for several days, but it always settles down after short period of time. Share this post Link to post Share on other sites
rayin Report post Posted March 23, 2023 I agree with previous replies. My old Dodge CTD 5,9 did that every time, but it always started in below 0°F weather.. Share this post Link to post Share on other sites
wildebill308 Report post Posted March 23, 2023 20 minutes ago, rayin said: I agree with previous replies. My old Dodge CTD 5,9 did that every time, but it always started in below 0°F weather.. I don't know for shure as I don't remember. I do remember that intake heater was a big load. Ray I just tryed to stay out of that colde of a place. Bill Share this post Link to post Share on other sites
rayin Report post Posted March 23, 2023 (edited) Bill all I had to do was stay home. I was still working then and going to work regardless of temperature was the norm. I worked 7 miles from our house so the 5.9 barely got warmed up and I was there. The Cummins ISB 5.9 in Dodge pickups was great, but Dodge derated the engine to 180HP to keep from destroying the Dodge automatic transmission, so it was a dog towing over a 35' 5er. Edited March 23, 2023 by rayin Share this post Link to post Share on other sites
mackandmaggie Report post Posted March 23, 2023 The rv is in fernandina Beach fl. Never been in cold weather or winterized. Freightliner couldn’t give me a definite answer. Just received the engine serial # and will get pdf for engine diagram Share this post Link to post Share on other sites
rayin Report post Posted March 24, 2023 (edited) 3 hours ago, mackandmaggie said: The rv is in fernandina Beach fl. Never been in cold weather or winterized. Freightliner couldn’t give me a definite answer. Just received the engine serial # and will get pdf for engine diagram Diesel engines work by heat, in fact they were originally called a heat engine. Anyway, look up the ignition flashpoint of #2 diesel fuel. A diesel engine combustion stroke must produce at least that temperature by compressing air until that happens. The Cummins grid heater heats the intake air just prior to entering the combustion chamber, in warm/hot weather it may only cycle once to warm incoming air enough to promote instant ignition when fuel is injected into the combustion chamber at the top of the piston stroke. When working properly the grid heater will cycle at least once with each cold start below 60°F. You can check to see if the grid heater is coming on prior to startup by removing the battery cable from the solenoid, taping the end and tying it out of the way temporarily. The Cummins B6.7 grid heater draws approx. 205A when cycling. Edited March 24, 2023 by rayin Share this post Link to post Share on other sites
