Billhump

Problem Solved- This 2006 Diplomat has a LEECE Neville alternator, which is different from the DUVAC alternator used in the Monaco models above the Diplomat. After some research and help from this forum, I began checking the Electrical Systems in the coach: Here is what I found. Alternator VDC output at the positive and negative terminals (engine running) 14.15 DC, the 3 auxiliary field (stator) terminals output 7.2 VCD each. When I rewire the alternator per 2006 Monaco diplomat wiring diagram, the alt/charge fail light and annunciator now work as they should. Special thanks to WATERSKIER-1 and all who provided help to me on this problem.

Rick, when Cummins checked this alternator, they indicate on the bill that they had 13.8 VDC on the battery studs of the chassis batteries. The chassis batteries are isolated from the house batteries with an isolation relay located in the main fuse box under the driver’s seat. The 2 chassis batteries are new and maybe 3 months old. I will check the VDC at the alternator this afternoon. I am presently going through the electrical system and have found the auxiliary lights, docking lights and mirror adjustments are not working now, but worked before alternator change out. My led daytime running lights are now pulsating when the engine is running. Thanks for your troubleshooting knowledge. It’s very helpful.

Thank you Rick N. The alternator installed on the coach at the factory was a Leece Neville #LBP 2180, Cummins service center replaced that alternator with a Leece Neville #LNLB 2180 GH. When I called Leece Neville today, they told me that the two alternators were the same. I believe this alternator has 3 field (stator) connections, the two large terminals which are ground and a 12 VDC main. There are no terminals for ignition or DUVAC terminal. Tomorrow I will check the wiring that I have and look for the 5 AMP fuse. Thanks again

We have a 2006 Diplomat - 400 ISL Cummins engine with an original LEECE NEVILLE #LBP 2180 160 Amp alternator. The original alternator was just replaced with a new LEECE NEVILLE # LNLB 2180 GH at a Cummins repair center. Now the ALT/Charge fail light will not go off. I told the Cummins Service manager that this light was controlled by the 6V terminal on the back of the alternator which goes to a 6V relay in the front bay under the driver's seat. After being at the Cummins Repair Center for more than a month, I have now picked up the coach and will troubleshoot the problem myself. I have talked to a Leece Neville service tech and was informed that all 3 terminals on the back of the alternator have 7.5V. I have tested the 6V relay socket for this circuit and have no power at terminal 86 with the engine on, and terminal 85 is the ground. This was confirmed by both a multi meter and the labels on the wires to the socket. The alternator is producing a 13.7V charge to the batteries. The horn, lights, wipers, and dash instruments all work. My first question would be: Is there a fuse between the alternator terminal and the 86 port on the relay socket? 2. Do all 3 terminal in the back of the alternator produce 7.5V? HELP!!