Fixing Dim Or Blinking Headlights - Quick Tech

You've added that larger output alternator, but things still don't seem right. Maybe the lights flicker, or worse, a wire has burned up. Well, your original '60 to '69 Mopar came with an alternator that could put out anywhere from 37 to 45 amperes. The output of the alternator is routed through the bulkhead connector to the ammeter and then back out through the bulkhead connector to the fusible link. There are several issues right away. First, the original alternator output wire in the harness is 12-gauge wire, and even in a short length, it's only good to about 60 amperes-and that's pushing it. Also, that high current is routed through the 30-to-40-year-old bulkhead connector-twice. It also goes through an ammeter that was not designed for more than 45 to 59 amperes. Depending on where the accessories are connected, wires could melt, lights could dim or flicker, or the accessories might not work correctly.

The remedy to this problem is actually quite simple and relatively inexpensive. When Paul Emiro of Sherrybrook Garage showed us his fix, we decided to install it on our Dart Sport. Now, however, thanks to Mopars by Crane, you can get the wiring upgrade kit to solve all these problems on your car.

The first part of the fix requires a length of 8-gauge stranded wire with ring connectors soldered on each end-crimping is not good enough! We used wire with the THHN type of insulation since it has a good temperature rating. This 8-gauge wire goes to the output stud of the alternator and to the large stud on the starter relay. Now the full output of the alternator can go to the battery and everything else. Make sure to remove or properly terminate the original alternator output cable.

The second part of the fix requires supplying enough field current to the alternator. The original alternator only required a few amperes to excite the field. A larger output alternator requires much more field current to yield their full output. By adding a relay, field current comes directly from the battery when the relay is turned on, not routed through the bulkhead connector and ignition switch. The original blue wire that went to the regulator is used to turn the relay on. Make sure the normally open contact is used so the voltage is applied to the regulator only when the key is in the "on" position. The later style regulator was designed for use with an up-to-100-amp output alternator and requires an isolated field (two connections) '70-and-later style alternator. The early style regulators may not be able to produce enough field current or may fail trying.

Keep in mind, with this fix the ammeter will no longer work properly. We recommend adding an aftermarket voltmeter that is hooked to a switched circuit. If you use a single wire alternator, it will still require the 8-gauge wire and the voltmeter.