I recently swapped the Philips HIR2 55w 9012 bulbs for my original Sylvania 9006 halogen low beams, and there is a definite improvement in brightness. My question is, would there be any practical purpose to installing a relay harness onto the HIR low beams to further improve the brightness, or would this simply put the bulbs into "overdrive" and reduce their lifespan without any tangible benefit (?)

In addition, is there any way to check the level of voltage that the low beam headlight socket is receiving? I have access to a multimeter, just not sure where to check.

Thanks

 

You do not need aftermarket relays to run HIR2 bulbs.

Technically, the car already has relays for the headlights, the aftermarket relay harness is to bypass part of the stock headlight circuit and power the headlights directly via the car's battery. The stock headlight circuit is still used to trigger the aftermarket relays, via separate wire routing. Relays are essentially switches.

I run HIR2 bulbs in my car without any bypass harness.

Any brightness improvement probably may be marginal, as there would be various factors to consider (such as quality of the aftermarket relays; and aftermarket wiring vs the car's existing wiring for the headlights).

You can test voltage on the low beam headlight sockets:

Left low beam socket: Voltmeter's red lead to cavity terminal (Red/Yel wire +) and Voltmeter's black lead to cavity terminal (Blk wire -)

Right low beam socket: Voltmeter's red lead to cavity terminal (Red/Grn wire +) and Voltmeter's black lead to cavity terminal (Blk wire -)

Info.: Honda's utilizes a dual mode charging system to increase fuel efficiency and reduce drag on the engine on start-up. The ECM/PCM determines charging based on info. from the Electronic Load Detector (ELD). During heavy load, the ECM/PCM can set charging voltage for high output (~14V - 15V). During light load and start-up, the ECM/PCM sets charging voltage for low output (~12 - 13V).

 

Great, thank you for the info redbull. I had read elsewhere that the voltage of the headlight should be check with the bulbs plugged in and the headlights turned on for the most accurate reading (also read some stuff about "volt drop testing", not sure what this refers to, or if it's even necessary in this application). How would one go about checking it with these methods? Thanks again

 

You can check the voltage with the bulbs out or in. If you check with the bulbs in, you would have to backprobe the socket from the wiring side.

Backprobing is either using a backprobe set or using a thin needle or something and making contact with the metal terminal of the connector without piercing the wire in the back of the still connected connector. Care must be taken to ensure that the wiring does not get damaged. You can use something like a T pin, available at Walmart, etc., and backprobe. These pictures are just to give a picture of the concept of backprobing without piercing any wires.

https://www.hondaaccordforum.com/for...%5D-t-pins-jpg

https://www.hondaaccordforum.com/for...back-probe-jpg

 

Thanks for the info. I'll give that a shot