Hello all, time for my first post. I joined the forum recently to do some research and try to diagnose issues I've had with the local FD's LMTV. I work for the fleet maintenance department for our local government in my area and we have an LMTV on indefinite loan to us from the US Forestry department. I think I've solved the problems that I had with the truck, but I wanted to add a thread, not only for my own future reference, but also for anyone else with a similar issue that could benefit from my experience with it.
The folks at the station the truck is normally stationed at don't like the truck and call it a "piece of junk" or say it needs to be put in a museum, but I'm of the opinion that it just needs to be looked after better by folks who have a bit of the right knowledge about it. The truck really is a joy to drive when it is working properly and if you know how to operate it's functions. The worst thing you can do to a vehicle is let it sit, run it for everything it's worth, then put it away wet.
Recently our LMTV had an issue with the batteries not charging. The unit had been used during the recent Florida storms and proper fording procedures hadn't been followed. I had to have the unit towed to the shop one night after the operators couldn't get it started following a trip to another fire station. We found that the battery disconnect relay was bad and no longer engaging due to already present corrosion getting worse after salt water exposure. We went ahead and installed 4 new batteries and a new battery disconnect relay, but still had starting issues. A shiny new starter along with cleaned off starter cables seemed to solve the starting issue (the salt water had it's way with the original starter). After that, as far as I'm aware, the truck was fine for the limited times that they used it afterwards.
A couple weeks ago, I got a call from the station that the unit wasn't starting again. When I got there, I found that the bus bars from the battery switch to the relay were corroded and a few of the nuts had melted from poor connections. I cleaned up the bus bars, all terminal ends, and installed them back into place with new nuts. Truck was fine again for a while.
A few days ago, I once again received a call that the unit wouldn't start. When I turned on cab power, the disconnect relay would engage, but before I had enough time to start the truck, it would disengage and continue cycling on/off until cab power was turned off. I inspected the vehicle and found a few faults. The main ground from the frame to the alternator had turned to powder from corrosion and the terminals on the alternator itself weren't in great condition. I cleaned off all the terminals on the alternator, had to install a new terminal on the wire going to the 14V side of the regulator, and hooked everything back up. I also made a new ground cable, cleaned off the mounting points with a wire wheel, and installed the new cable. I tested all the batteries and cleaned up all the terminals on those as well, verifying that everything was hooked up correctly. The disconnect relay would now stay on for longer, but was still cycling. I decided to bypass the disconnect relay with a set of jumper cables to get the truck running. Once it was running, I removed the cables and I could get a few more start cycles before the disconnect relay started acting up again. While the truck was running, I noticed the red BATT DISCONN light was on and the voltage gauge was pegged at 28V. I went ahead and lowered the spare tire so I could access the Polarity Protection Device. I cleaned the terminals on there and hooked everything back up. The relay was no longer cycling and I could start the truck as normal (this was before I knew that you could unplug the PPD to bypass the disconnect function). The truck is now charging at just under 26V on the gauge and the red light is also off. I will continue to monitor the unit and post any updates.
The folks at the station the truck is normally stationed at don't like the truck and call it a "piece of junk" or say it needs to be put in a museum, but I'm of the opinion that it just needs to be looked after better by folks who have a bit of the right knowledge about it. The truck really is a joy to drive when it is working properly and if you know how to operate it's functions. The worst thing you can do to a vehicle is let it sit, run it for everything it's worth, then put it away wet.
Recently our LMTV had an issue with the batteries not charging. The unit had been used during the recent Florida storms and proper fording procedures hadn't been followed. I had to have the unit towed to the shop one night after the operators couldn't get it started following a trip to another fire station. We found that the battery disconnect relay was bad and no longer engaging due to already present corrosion getting worse after salt water exposure. We went ahead and installed 4 new batteries and a new battery disconnect relay, but still had starting issues. A shiny new starter along with cleaned off starter cables seemed to solve the starting issue (the salt water had it's way with the original starter). After that, as far as I'm aware, the truck was fine for the limited times that they used it afterwards.
A couple weeks ago, I got a call from the station that the unit wasn't starting again. When I got there, I found that the bus bars from the battery switch to the relay were corroded and a few of the nuts had melted from poor connections. I cleaned up the bus bars, all terminal ends, and installed them back into place with new nuts. Truck was fine again for a while.
A few days ago, I once again received a call that the unit wouldn't start. When I turned on cab power, the disconnect relay would engage, but before I had enough time to start the truck, it would disengage and continue cycling on/off until cab power was turned off. I inspected the vehicle and found a few faults. The main ground from the frame to the alternator had turned to powder from corrosion and the terminals on the alternator itself weren't in great condition. I cleaned off all the terminals on the alternator, had to install a new terminal on the wire going to the 14V side of the regulator, and hooked everything back up. I also made a new ground cable, cleaned off the mounting points with a wire wheel, and installed the new cable. I tested all the batteries and cleaned up all the terminals on those as well, verifying that everything was hooked up correctly. The disconnect relay would now stay on for longer, but was still cycling. I decided to bypass the disconnect relay with a set of jumper cables to get the truck running. Once it was running, I removed the cables and I could get a few more start cycles before the disconnect relay started acting up again. While the truck was running, I noticed the red BATT DISCONN light was on and the voltage gauge was pegged at 28V. I went ahead and lowered the spare tire so I could access the Polarity Protection Device. I cleaned the terminals on there and hooked everything back up. The relay was no longer cycling and I could start the truck as normal (this was before I knew that you could unplug the PPD to bypass the disconnect function). The truck is now charging at just under 26V on the gauge and the red light is also off. I will continue to monitor the unit and post any updates.
