ignition
@4spdragtop
Here's two examples of how to look for the bad wiring in this path where the current is flowing. It must be flowing to show resistance.
Instead of measuring voltage to ground reference, we will use the voltmeter directly to look for drop.
Red probe to the high voltage point, and black probe to possible lower voltage point.
We find 2 volts between the battery post and the solenoid stud.
Therefore there must be excessive resistance between those two locations.
The problem must be in that cable or its connections.
Next example:
We find no voltage between the battery post and solenoid stud. Move on.
We find also find no voltage between solenoid and firewall side of connector. We can't move on because our leads are too short and we have nothing to make one longer. OK. So here we take a voltage reading to ground and compare it to the Battery positive to ground. We'll call this voltage B. We don't care if its 9 or 12 Volts, as long as its the same. On the other side of the firewall, terminal connection to ground is 0.1 Volts less. Some resistance, but alone not a problem.
Continue checking for voltage drops all the way down the line to the headlight switch connector.
Between the ammeter's alternator side stud and the headlight switch's B1 feed, we find nearly 2 Volt drop.
Therefore there is excessive resistance in the wires or connections between those two points. Probably around the ring terminal and wire that connects to the ammeter but possibly at the main splice.
(If it was after the main splice we would not see the drop at the ignition switch. With key off, the wire from the main splice to the switch is just like an extension of the voltmeter probe)
@4spdragtop
Here's two examples of how to look for the bad wiring in this path where the current is flowing. It must be flowing to show resistance.
Instead of measuring voltage to ground reference, we will use the voltmeter directly to look for drop.
Red probe to the high voltage point, and black probe to possible lower voltage point.
We find 2 volts between the battery post and the solenoid stud.
Therefore there must be excessive resistance between those two locations.
The problem must be in that cable or its connections.
Next example:
We find no voltage between the battery post and solenoid stud. Move on.
We find also find no voltage between solenoid and firewall side of connector. We can't move on because our leads are too short and we have nothing to make one longer. OK. So here we take a voltage reading to ground and compare it to the Battery positive to ground. We'll call this voltage B. We don't care if its 9 or 12 Volts, as long as its the same. On the other side of the firewall, terminal connection to ground is 0.1 Volts less. Some resistance, but alone not a problem.
Continue checking for voltage drops all the way down the line to the headlight switch connector.
Between the ammeter's alternator side stud and the headlight switch's B1 feed, we find nearly 2 Volt drop.
Therefore there is excessive resistance in the wires or connections between those two points. Probably around the ring terminal and wire that connects to the ammeter but possibly at the main splice.
(If it was after the main splice we would not see the drop at the ignition switch. With key off, the wire from the main splice to the switch is just like an extension of the voltmeter probe)
