I have a 2013 SRX and had this problem develop slowly, and I did solve it by having the headlight assemblies replaced. But my trek to get there is perhaps worth sharing: I know that on old cars, dim headlights often result from corroded ground. It's an electrical light, after all: it has to be on the supply side (not enough current, probably amps not volts) or on the ground side. First I tried simply replacing the original bulbs with new bulbs, ostensibly brighter than the original. If anything, the lights were even dimmer with the new bulbs (and certainly were no brighter.) This eliminated anything to do with the bulb itself as the problem, no matter whether it was ground-side or supply-side. I put the old bulbs back in, and started experimenting. I rigged up a way to run a separate ground to the drivers side light (which is much easier to access), by running a wire from the chassis into the plug along with the bulb, and I didn't see any difference. So I figured it was on the supply side, and I suspected that the circuit that controlled the daylight running light mode was perhaps degrading over time, resulting in fewer amps coming to the bulb. (I think the daylight mode is created by reducing the amps that come to the bulb, and that the voltage remain constant.) I determined that the low beam lights, though not bright enough, were still a lot brighter that the daylight running mode. (I did this by pulling into and out of my garage, and seeing the lights get noticeably brighter and dimmer, as seen in a mirror I placed directly in front of the car). So I thought I'd rig up another supply path straight from the battery to see if the bulbs were brighter if I could set and hold the amps constant. Before I could get this rigged up, I did something (inadvertently) that caused a relay to fail (open) somewhere in the headlight circuit for the driver's side only. So that low beam light was out altogether, whereas the passenger side light had not been altered. This was really dangerous, as that one light alone was nowhere near bright enough to drive. So I had the dealer find the problem: the technician detected the open relay. I had them replace that drivers side headlight assembly only. The result was that the drivers side light was back to its normal, "new" brightness, and it was OK to drive that way. The drivers side light was much brighter than the passenger side light. After a few months, I had the dealer replace the passenger side headlight assembly as well, and now they both look like new.