About four years ago I installed an IBS-DBS from Sierra Expeditions. (As some have pointed out this particular system is far more expensive than other systems out there but I pulled the trigger on it anyway. That is not what this thread is about.) I installed it in my UZJ-100 without issue. It went in easily and worked very well - for a while. When I bought the system I added the RBM (Relay Booster Module) which is supposed to help in protecting the system in the event you need to jump your own starter battery with your accessory battery. "RBM Relay Booster Module: designed to improve the functionality of the IBS-DBS Dual Battery System (IBS-DBS and DBi-DBS) in the event that the starter battery is empty or fails totally." I was running an Optima blue top as my accessory battery and a Sears Platinum Group 31 as my primary starter battery. Fast forward about three years. The first thing that happened is while on a long hot drive in the Philippines the controller began to beep and the green link light illuminated. I played with the controller a bit to see if I could make this stop and I found linking and unlinking the batteries manually would make the condition revert to regular operation. I read this in the IBS-DBS trouble shooting "manual" which there really is not much to: "Link failure alarm: The monitor monitors the charge on both batteries. When fitting charge (from alternator, solar, charger) no charge to the other battery is detected, the link error alarm with flashing green LED "linked" and the "beep" sounds. If this error occurs, check immediately the wiring of the power cables to (relay, battery terminals, crimp contacts, control relays). After bug fixes, the alarm will automatically reset." I inspected all my connections and found nothing wrong. I do not drive the truck much here in the Philippines and often only drive short distances. The problem did not present again for a while and then my Sears G31 battery started failing. When I drove more than about 45 minutes, the error started to present again. Eventually, after about 6 months or so, the G31 battery was garbage and I replaced it with an Optima blue top G31 (which are about 2 times the price here as in the states. Ouch. But other batteries here are junk.) Problem not solved. And as a matter of fact, it was getting worse. It started to happen after 20 minutes. Ten even 10 minutes of driving. Eventually I recognized that the accessory battery was only being charged for about the first ten minutes of driving. After that, a malfunction caused the system to ignore the accessory battery. It showed on the controller in the cab and I watched as it would drain when using my fridge. I contacted Wil and Sierra Expeditions and he thought it could be a bad main 200amp relay. I also did some searching and found someone in another forum having a very similar problem his solution was to remove the RBM (which is an option) completely. He also was driving in harsh hot conditions. But because I do not pay attention to what I read, and it was going to be easier to replace the main relay than remove the RBM, I went ahead an got a new main relay from Wil. It was far cheaper than the RBM as well so I figured it was worth a shot. (In retrospect I should have just removed the RBM and kept my $30 but I bought a Trasharoo at the same time but I digress.) Once installed there was no change to the system. It continued to fail. This Thursday I finally got around to getting in the 120 Fahrenheit basement to remove the RBM. Problem solved. Like the guy in the other forum, my RBM had failed and was preventing my system from operating. Closer inspection also revealed that the sealant on the RBM was no longer intact. I am guessing the heat and humidity of the Philippines destroyed the internals. Wil was quick to respond to my emails and I appreciate that. There was no way for him to have known the true problem. Unfortunately, because I installed the system myself, it only has a three year warranty, if someone else had done it for me, I would have a five year. Go figure. In summary, if you have a IBS-DBS with an RBM and start getting a flashing linked light and alarm after a short time, remove the RBM from the system first. It is likely the culprit and the easiest thing to do - even easier than inspecting all your connections and wires, as a troubleshooting step.