Headlight Relay Kit

[Roger W.]

https://digital.allchevyperformance.com/issue/june-2025rm/how-to-get-brighter-headlights-for-your-vintage-muscle-car/

The topic of using Halogen headlights in a C1 has been previously discussed. This kit seems to be an easy fix.

[Patrick H.]

The article doesn't directly address this, but my question with these kits is if this can be done without modifying (cutting, splicing) the original wiring at all. I don't mind cutting and splicing kit wiring, but I'm not about to cut my original wiring to add this.

[David H.]

Headlights only thing affected by old wiring?

Dave

[Dave P.]

The article doesn't directly address this, but my question with these kits is if this can be done without modifying (cutting, splicing) the original wiring at all.

Sure. You can purchase Packard 59 series male and female terminals, as well as a 3 cavity connector shell that will plug into the existing headlight connector. You use the existing circuits as the trigger / control source for the relay coils. Fabricate a stand alone harness from the relays to the headlights, or in a C2 I'd go to the connector between the forward lamp harness and the bucket harness.

The kit looks like it has wire, terminals and connector shells. You're building your own harness anyway. You would need an Aptive 8917857 connector shell, and (3) 8905807 terminals for the interconnect to an existing low-beam headlight connector. Probably available from Mouser.

What the article isn't clear at conveying is how to determine the existing voltage drop, and predicting improvement. Measure voltage drop on a circuit by placing the leads of your voltmeter at two different points in a circuit. The volt reading is the drop between those two points. Place one lead on the headlight connector tan or lt green and the other on the alternator output with the engine running. This is the voltage drop on the (+) side. Do the same between the black wire at the headlight connector and the alternator case. This is the voltage drop on the (-) side. Add the two together for total voltage drop between system voltage and voltage at the bulb.

If the existing drop is appx 1 volt or less, there isn't going to be a lot of improvement. To assess whether the relay mod is going to be a meaningful improvement try this: With the headlights ON take a piece of 12ga wire and insert it in the backside of the headlight connector (tan = low beam, lt green = high beam) and the other end to your proposed voltage source for the relays. (Horn relay, alternator output, or battery +.) Note the difference in intensity with and without the jumper. If it isn't significant, you may conclude that the relay mods are not worth the effort.

The relay mod won't address or improve voltage drop on the (-) side. You can use the jumper method cited above for the (+) side on the negative side to asses possible improvement on the ground side. You can incorporate new larger gauge negative wiring in your stand alone harness, and ground directly to the engine block or alternator case.

[Roger W.]

We have had posts by owners' of c1s who have installed Halogen headlights and the circuit breaker in the headlight switch kept tripping. This kit would solve that problem.