Recently had a bunch of paint work done on my volvo TAMD-74P EDC engines. The alternators were removed as were several other components as part of the process. After reassembly, I'm getting battery alarms at the helm and I'm only seeing 12-12.5V when running without the battery charger on. The alternators have a terminal labeled "61" that should have 12v applied to it to energize the alternator. I've heard folks refer to it as an exciter wire. However, I do not see any meaningful voltage on this wire when the engine is on and running when measured between the 61 post and the negative on the starter. I've traced the wire and it runs to the black junction box on the engine and then up to the flybridge. After that I lose track because the wire seems to change color somewhere in the harness connections. Does anyone know where this wire would be connected? Some folks say it would be connected to the warning light panel, but somehow it's gotta have 12v on it. I'm trying to figure out where the disconnect is. I'm hoping theres just a blown fuse up there somewhere that I haven't found yet. The boat is a 2000 42' post SF. Any further troubleshooting suggestions would be appreciated. I'm in the Bahamas right now and would like to get this sorted before we cross back.
Does it charge when that exciter wire is jumped to the positive post? I did not realize the alternator was removed for painting. Is the case of the alternator making good (ground) contact with the block?
I tried connecting the positive alternator post to the “61” exciter post with a 14 ga alligator clips jumper and it flashed, insulation caught fire, and incinerated the jumper wire all in about 2 seconds. I’m not sure if the alligator clip grounded against the back of the alternator or what but it was…dramatic.
Ok here are some measurements from the port side, which does not have house loads. Battery charger off. 12.66V from positive to negative alternator post 12.6V from alternator positive to engine ground (bolt head) 13-13.1V from alternator positive to “61” 450mV (0.45v) from “61” to engine block bolt/ground so, it seems the “61” wire is at a 0.45V lower potential than the engine ground. I should note I also see that ~0.45v potential difference between engine ground and the 61 post when the engine is off/not running
Please post a pic of your alternator back. Point out what you think is the 61 wire. Late Monday night, have a note in to my VP tech just now. A pic may help. ,rc
