Going crazy with new Duster and over voltage issue.

Contrary to popular belief, the ballast resistor is rarely the problem, nor is the voltage regulator. It’s probably a connection problem, possibly more than one connection.

What voltage did you measure between key switched feed at ballast resistor and battery positive? As mentioned above, more than 0.3 V is a significant drop in the ignition circuit that requires investigation.

If you measure a 1.5 V drop, this may give you a charging voltage of ~16 V because the voltage regulator will think the system is running 1.5 V lower than it actually is.

If your measurement is higher than 0.3 V follow the path Del (67dart273) outlined above and measure each connection in your ignition circuit.

The drops add up and are cumulative. For example, you may have 0.3 V at the bulkhead, 0.5 V in the ignition switch connector, and 0.4 V in the ignition switch itself, for a total of 1.2 V.

I worked through this same issue earlier this year with Del’s assistance and it turned out to be a cumulative problem, most significant drops were the ignition switch connector and the ignition switch. It’s important to do the measurements.