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03 f250 6.0.... replaced both batterys and volts have been around 11.9 to 12.9.. fluctuates alot. Checked alternator and passed. Noticed previous owner had supee glued pigtail on alternator due to locking pin breaking. Its on pretty tight but could this be my issue? If so ive heard about some being available for $5. Thanks in advance
03 f250 6.0.... replaced both batterys and volts have been around 11.9 to 12.9.. fluctuates alot. Checked alternator and passed. Noticed previous owner had supee glued pigtail on alternator due to locking pin breaking. Its on pretty tight but could this be my issue? If so ive heard about some being available for $5. Thanks in advance
Where are you reading the voltage from? Scan Gauges are usually .5 volts off actual. Voltmeter is the best and most accurate.
Also are the cable ends clean. Both the ground and power sides on both ends.
That means you may have to trace the ground cables to the frame and block.
The one on the passenger side is near the A/C compressor and frame and the driver
isde is under the air-filter near the frame head.
You test you can do with ha DMM (Digital Multi Meter) is a Voltage Drop Test.
Here is a example on Youtube.
The key thing being at high currents even a little increased resistance in a cable
can cost you a lot of power.
One place a problem can hide in under cable insulation. It may "look" good but
it can hide all sorts of corrosion and rob power. Never assume a cable is good
by looks. The Voltage Drop Test is free just you time.
I monitor volts from a autometer guage, a edge cs and torque pro. They all are pretty even. I also have disconnected both batterys and checked volts with fluke meter. In addition, my alternator wire is 0guage and a 200a fuse. All battery terminals are fairly new. No corrosion what so ever.. positive/negative wire are 0ga aswell. :/
Use the steps from the voltage drop test and put one probe on the battery +
term and the other one on the stud from the alternator stud. Do this so that
that adaptor is part of the section your testing to see if that adaptor is adding
resistance to that circuit.
