ignition
If the key was in Accessory, it would be flowing to the key switch, then out the accesory wire to the fuse.
If the key is in Run position, it would do that in addition to the current flowing to the alternator field and the ignition.
Lets say
Heater fan draws 7 amps on high.
Field draws 2 amps
Coil draws 1 amp, and if there's an ECU, it draws an amp or 2 as well.
= Total of 10 to 12 amps.
Then the flow would look something like this. If there was a bad terminal on the wire from the ammeter, it would still show in the same voltage drop check as in the headlight example. But with heater on, we can also check for drops at and in the keyed switch and its connections.
As before, all of the red rectangles should have the same voltage as battery positive, if there's no resistance along the flow path.
The dark rectangle on the other side of the ballast resistor will have lower voltage as long as there is current flowing through the coil (points closed);
Is this with the switch in run or off?
Correct!
If the key was in Accessory, it would be flowing to the key switch, then out the accesory wire to the fuse.
If the key is in Run position, it would do that in addition to the current flowing to the alternator field and the ignition.
Lets say
Heater fan draws 7 amps on high.
Field draws 2 amps
Coil draws 1 amp, and if there's an ECU, it draws an amp or 2 as well.
= Total of 10 to 12 amps.
Then the flow would look something like this. If there was a bad terminal on the wire from the ammeter, it would still show in the same voltage drop check as in the headlight example. But with heater on, we can also check for drops at and in the keyed switch and its connections.
As before, all of the red rectangles should have the same voltage as battery positive, if there's no resistance along the flow path.
The dark rectangle on the other side of the ballast resistor will have lower voltage as long as there is current flowing through the coil (points closed);
