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hello guys. So I picked up a new to me 2008 f250 last week. While driving almost every 10-15 seconds the dash, radio, gauges, would cut off and cut on constantly and the battery light was on. When I ran the codes I got a B1317 or high voltage. I measured the voltage through my scanner while driving and in fact it would jump up to 16-17 volts while driving.... not good. I checked the battery connections and the alternator and everything seemed tight and good, so today I replaced the alternator with an ultima 200 AMP reman alternator. First drive with truck absolutely no issues. Second drive the check engine light comes on and I have the same B1317 code, however nothing is cutting off so I am happy about that. Does anyone have any ideas of where I should look next?
unplug the PCM control harness at the alternator...then check your voltages ....after stabilization with the harness off and a good battery.. you should get 13.75 volts. this is the voltage out put of the alternator in DUMB mode. after stabilization, if you are not getting this...theres a defect in either the alternator or the battery.
with the PCM control harness connected to the alternator and a good battery you should get 13.75 - 14.5 volts (alternator in SMART mode) depending on air temps.
Here’s what I found with a multimeter. I’m starting to wonder if I gave it enough time for the system to “stabilize”... how long should that take after starting?
Alternator plug disconnected truck not running
13.37 battery
13.35 alternator
