HI guys,
We keep getting an RPM error, which when we run the code, it is a voltage fault (spn 168 FMI 17). We get the fault after we have been boating for 3-4 hours, it is now very repeatable. We also notice the voltage starts around 13, and slowly drips down to under 10, and then rapidly will drip down to 7-8, and we're done. We have had to jump start it twice on the lake to get it back to the dock.
Sounds simple, but we have tested both batteries, they are good. We even replaced one that was older (even though it tested good), in hopes that was the problem. We took the alternator off and had it tested at an alternator shop and it came out just fine (oem alterator, 300 hours on the engine).
Our conclusion is simply that the batteries are all charged up when we leave the house (because we always plug it in when its sitting),but clearly they are not being maintained by the alternator when out on the lake, and we run down over 3-4 hours. Our boat has 3 stereo amps that suck power as well, but we even turned off the stereo last time and it still happened.
We are thinking alternator, or cabling problem to the battery?
Any suggestions? Its at an alternator/battery shop now. We're having the alternator and pathways tested again.
thanks, as always