captjima Report post Posted July 13, 2015 I have noticed that when the engine was under load that the voltmeter would trend downward. The engine quit once but restarted by itself before I could get off the road. Twice I have got a low voltage alarm. Getting ready for summer trip, I started the engine and it ran for about a minute and quit. I drove the rig 100 miles last week with no problem.Batteries are new. Engine cranks gauges work with the exception of the voltmeter. Any help is welcome. Newmar Mountianair Cat 3126 Freightliner X/C Share this post Link to post Share on other sites
huffypuff Report post Posted July 13, 2015 If you get it started again, put a voltmeter on the chassis batteries to see if it's charging. Electronics and solenoids don't like low voltage and will shut down the engine. Share this post Link to post Share on other sites
wolfe10 Report post Posted July 14, 2015 captjima, Welcome to the FMCA Forum. As Ray said, all modern electronic engines are sensitive to very low voltage. You need to find the source of the falling voltage. Could be as simple as a bad connection at a battery post. Could be a failing alternator. Troubleshooting is pretty basic and little different from a 1950's Chevy. Suggest you get it fixed before starting the engine again. Bad voltage/voltage spikes can damage electronics. Share this post Link to post Share on other sites
DaveAtherton Report post Posted July 14, 2015 Yes Electronic Cat engines need correct voltage without question. There are sensors and regulator that will either Derate engine or ECM will shut down engine. Just signed in today. Dave Atherton Retired Cat Mechanic Share this post Link to post Share on other sites
dickandlois Report post Posted July 14, 2015 Hi Dave Welcome to the FMCA Forum! Glad you decided to join in on the fun! LOL You and the Wife parked next to us in Redmond for a few days. Think your wife may still be making one dish you like in the Microwave. Now I have to ask, are you going to be in Madison for the Rally?Rich Share this post Link to post Share on other sites
DaveAtherton Report post Posted July 14, 2015 Newmar 2000, been thinking your problem is not all low voltage, reason you indicated engine quit in moving off road and restart and going again. New batteries check alt for output voltage. If charging tells engine is getting correct voltage and possible fault gauge or connection. Here is where I'm going , you have a 5 volt sensor going bad, connection to sensor dirty. Would suggest check out your charging system and than drive motorhome. Problem happen again off and on because this is a event code that will reset itself and you will go again. If this happens again get with Brett and we will get you going. If what sensor I'm thinking will take about 15 minutes to install at a Cost of aprox. $ 137.00. Dave Atherton retired Cat Mechanic Share this post Link to post Share on other sites
DaveAtherton Report post Posted July 14, 2015 Hi Dave Welcome to the FMCA Forum !Glad you decided to join in on the fun ! LOLYou and the Wife parked next to us in Redmond for a few days. Think your wife may still be making one dish you like in the Microwave.Now I have to ask, are you going to be in Madison for the Rally ?Rich ! Yes, we will be working with the Beaver Group doing security. Dave Share this post Link to post Share on other sites
hermanmullins Report post Posted July 14, 2015 Rich, Where will you be working in Madison? Bobbie and I are on Water Service. Herman Share this post Link to post Share on other sites
captjima Report post Posted July 14, 2015 The chassis batteries are 2 weeks old and fully charged. I had the alternator tested and its OK. I installed a new belt tensioner and belt last year. I can't do too much until I am able to start the engine. Share this post Link to post Share on other sites
wolfe10 Report post Posted July 14, 2015 I would start (yes before starting the engine) by carefully cleaning and tightening connections at the batteries, and engine. And check the same up front at the ignition solenoid and any circuits that have to do with the Allison or Caterpillar. This includes the negative/ground connections. Clearly if the batteries are new and fully charged (12.7 VDC or above) at the batteries and not "further downstream" there is a problem. A digital voltmeter will be your FRIEND. Use it to verify that you have the same or close to the same voltage at the different points that you have at the chassis batteries. After doing this, I would turn on the ignition (not try to start the engine) and verify that voltage is still 12.2 VDC or more at these various places (voltage under load can drop, particularly if a poor connection between battery and the point you are checking it). Share this post Link to post Share on other sites
dickandlois Report post Posted July 14, 2015 Rich, Where will you be working in Madison? Bobbie and I are on Water Service. Herman Working Security and maybe carts. See you in about 10 days. OH, I think your PM file is full, PM was rejected. Rich. Share this post Link to post Share on other sites
