Originally Posted by Guitplayer
1 I`ve pulled the negative off the battery while the truck was running.
No change in the motor or headlight brightness. ALT is good?
2 Its having a hard time cranking,like the battery is low. I am trying to diagnosis this so I don`t get stranded.
3Strange the voltmeter drops as I change heater motor speeds. Is that a sign of something?


The battery seems fine. 327sbc

1 --- Its good as in outputting enough current without the battery. Its not a full test but most likely not your issue since you are referring to cranking as the issue. --- Don't leave that battery disconnected for long period of time.

2 --- Easiest way is swap it with a known good battery. If it cranks better then most likely other battery is not holding enough amps. If no change and still hard to crank could be other issue like starter or wiring with to much corrosion or bad contact to locations etc.

3 --- No that would be normal you are adding more windings and amp draw all affecting volts. volts = amps x resistance

Last edited by Gdads51; 11/14/2024 3:55 PM. Reason: cleaned up to separate original quote questions and provided answers