Hey all, I'm having a weird headlight issue and aside from discovering that this gen of Prius has a lot of headlight problems, I wasn't able to determine the next step in troubleshooting mine. Hoping this group can help identify what could be wrong. Initial symptom I was looking at is that the passenger side low beam is dim. It is correctly installed, the plastic is clear and clean, but the bulb is dim. Upon inspection, not only is the low beam dim but the high beams are both on but also dim when the low beams are on. Flipping the high beam switch turns on the driver's side high beam, but all lights on the right side (low, high, marker?) turn off completely. Hopefully the pics make this clear. I changed the low beam bulb, checked fuses, and at least took a cursory look for bad grounds or damaged wires. Looking at the wiring diagram I'm not sure how this could happen other than a bad relay but hoping this group can provide some ideas. Summary: Low beams on: Driver side low beam on, driver side high beam on but dim. Passenger side low beam on but dim, passenger side high beam on but dim. High beams on: Driver side low and high beams on and 'normal', all lights off on passenger side.
Well if it's the relay then your banking on a dirty contact or something to be supplying not 12 volts something less that would seem to be like a stretch You could just measure on your low beam bulb and see that you have 12 point whatever volts there to be certain there's at least 12 You're running halogen lights I'm assuming so it's possible there could be a socket or plug issue I'm running all LEDs in the Gen 3 that still together which is a 13 persona and the headlights are impeccable as a Gen 3 goes this is the single fixed projector fake projector whatever you want to call it cut off seems to be good with the LEDs and they are very bright and the color Kelvin matches the LED running lights in the front bumper cover. I know in some Gen 3 and 2010 2011 maybe I'm not sure there was a wiring harness issue maybe this can be part of that problem Not sure.
Yeah, I'll have to take the multimeter to it. Since the high beam bulbs are turning on but also dim I was thinking that the relay that switches between them might be partially failed and 'leaking' when the lows are on. I need to look at the diagram again too. Do you have a link/part # for the LEDs you are running?
Aux beam S series I have s1 in they're now now fans on them . They've been in about 2 years on one car and a few longer on another I used this brand almost specifically they are available through Amazon through the AUX b e a m store I have some other models that I've used but their fan models they don't last very long to make noise and have a box full of them here I need to get them to the trash in a generation 3 if the halogens haven't sucked the wiring harness to crap or whatever goes on here in my two generation 3s which are h8 and h11 bulbs I have the same branded lamps with the factory harnesses that have never been touched that I know of and I have had no headlight problems in either of the generation 3's the 10 and the 13 since I've owned the cars matter of fact those have been the things that work the best on the generation 3 is the headlights or the lights. With these LED bulbs The rest of the car has been in other disaster and now thank God both of them are off the road sitting in the driveway The lights and all the ancilliaries work fine. The door panels are caved in and the engines are worthless but other than that they're pretty yard ornaments Time to get them stripped and out of here
From a quick look at the diagram I'd definitely want to see what was going on at the DIM relay. I don't think it switches between the two as much as just turns the brights on and off. You could pull it and test the load side for continuity as a quick check that it's not stuck closed (should be open when pulled). Perhaps there's a similar relay you could swap it with? I'd also want to check that the ground to A2 (all the RH lights) is solid. If you have a spare bulb and could possibly make a test light you would hook one side to battery positive and one side to the ground of one of the RH lights (close to the bulb as possible) and see if you get a dim or bright light. I wouldn't consider LED's until you have the situation figured out.
Very likely a ground problem at the A2 or A3 ground points for the headlights or at the ground junction for either the left or right side near the headlights. The A2 or A3 chassis grounds may look ok but not be cleanly grounded to the chassis. This would cause a floating ground on the bulbs. Same thing could happen at the junction points on either side. Temporarily adding a separate ground on the white/bk near the bulb connectors on each side would be a good diagnostic.
A2 chassis ground seems to be it. At least I think that's the one: Brown wire at the attachment point in front of the RH wheel well was damaged inside the connector. Jumping it caused the lights to work as expected. One additional symptom that helped me think this through was that removing the bulb from the connector on the RH high beam caused the entire RH light assembly to all get no voltage just like when turning on the high beams. So when the lows were on current was finding a path through the high beam circuit, and when that circuit was engaged by the relay it no longer provided that path (?). Thanks for the help!
Wait until you get a floating neutral bus bar in the main breaker box of a home. Some circuits go way higher than 120v while some go low.
I've wired up both or three buildings here on the property full 200 amp services etc I try not to have any of that going on kind of a pain in the .
Actually I love doing my plumbing I've plumbed up my 200 ft well pump My bladder tank which is 100 gallons and all my 1-in water piping to three buildings I don't think I would leave that to somebody else personally.
Yes. You perfectly described classic symptoms of faulty headlight grounding. It's not uncommon on cars in general, especially old ones.
