Which way you working?
If working from battery, looking for drops, I tend check at the solenoid relay, then the bulkhead engine side. Then the next in sequence would be the ammeter. Because of easy access, I usually skip ahead to bulkhead out to resistor and then go inside to the ignition switch 'cause its in the dash.
Some depends on what loads are on. Remember it only drops when there is current flow. ECU on and coil will draw some current, fan or lights will draw alot.
I wouldn't unwrapp around the welded splice unless you have a reason to based on voltage drop before and after.
