Headlight Relay Update

Here's a way to replace the 3 relay system in your Charger with 2 relays that are available from Radio Shack.

The original headlight relays were all SPST relays, or Single Pole Single Throw. This means that they had a single input and a single output. The Radio Shack relays (12V 25AMP) are SPDT relays, or Single Pole Double Throw. This means that they have a single input, and both a Normally Closed and a Normally Open output. This allows us to combine the functions of the Open and Control relays into ONE relay!

Here's a picture of the relay base.

Here's a schematic showing what each pin does.

Pins 85 & 86 are the relay coil. Pin 30 is the power input, Pin 87a is the Normally Closed output, and Pin 87 is the Normally Open output.

When power & ground are applied to the coil, the "switch" inside the relay is pulled down from the Normally Closed contact to the Normally Open contact.

 

Okay, so how do we use 2 relays to replace 3? First, we will need the 2 relays, some 10 or 12 gauge wire, a pack of 10 yellow male spade lug connectors, a pack of 10 yellow female spade lug connectors, and some wire cutters and terminal crimpers.

Make seven jumper wires, about 4" to 6" long, with a male at one end and a female at the other. Make one more jumper with a female at each end. Now remove the old relays from the car, and disconnect the battery.

Take the connector for the Open Relay, and one of the new relays. This will be the Open/Control Relay. Put a jumper from pin 30 to the thick red wire, a jumper from pin 87 to the thick purple wire, a jumper from pin 85 to the Light Green wire, and a jumper from pin 86 to the Black wire.

Now take the other new relay, this will be the Close Relay. Take the female/female jumper and connect pin 87a on the Open/Control relay to pin 85 on the Close Relay. Take the connector for the old Close relay and the new Close Relay, put a jumper from pin 30 to the thick Red wire, put a jumper from pin 87 to the thick Red/Orange wire, and put a jumper from pin 86 to the black wire.

Mount the relays using the old mounting screws, and re-connect the battery. You're done!

Here's a schematic of the relay conversion.