2007 Prius no Power to Halogen Headlights Hi or Low beams

Hi all,

I am new to this forum and new to the Prius as well. I just purchased a higher mileage 2007 to use for a shop vehicle to try to save us some bucks annually. (I am a used car dealer) I didn't buy this one for resale. I bought it to save money on gas.

All that said, Everything seems to be working great except for the headlights... I have no power to the headlight sockets, and no power to any of the fuses. Both High and Low fuses for both sides are not getting voltage while the lights are turned on. (Multi-meter to ground and socket as well as fuses. Both with and without fuses installed to test for voltage)

Inside the vehicle there are no warnings or indications that there is a problem with the lights. When I turn the lights on, I get the green light on the center of the dash, and when I pull the high beams, I get the blue light on the dash.

I have replaced the Headlight sockets, the halogen lamps, the Headlight Relay, and also the lighting control module under the dash (On the fuse block under the dash)

I think our next step will be to check connections on the back side of the fuse panel in the engine compartment then trace the wires from the bottom of the engine compartment fuse panel back to the fuse block under the dash or where ever it goes.

I am a mechanic, this shouldn't be a big deal, but I am stumped...

Is there something obvious, as a new Prius owner, that I am overlooking?

Appreciate any input I can get!

 

Thank you. It seems we are on the same track. Hopefully I'll have lights tomorrow.

I didnt think to jump the power across to see if I can get it to the socket.

It reminds me of a Saab story I had to bypass a relay to diagnose. This one should be easier.

Thanks again and I will surely update my results.

Chris

 

Going to get the lights on today, i am determined to solve this today. But, I have a dumb question, even though I believe there are no dumb questions.

Currently I have the headlight assemblies out of the car and the sockets are dangling in the engine compartment. Is there any stupid chance that the lights don't work unless they are in the headlight housing?!

Just had to ask. I would love to slap my forehead today.

 

Yea, I knew I wasn't that lost...

Okay, so far today I proved that my halogen bulbs work. I jumped the wire from the fuseable link to the disuse and the lights came on. I used a 12v battery to test the headlight relay and they are working too. But, I put my multimeter on the plugs for the 12v relay and I am only getting 9-10v for the delay when I switch the lights on. Not enough to pull the relay.

And there lies my problem.

I will continue poking and probing. In the garage now...

Where am I losing 2 volts from the switch to the relay?

 

Mark this one as solved.

I determined it had a bad ground at the relay.

I turned the switch on and using my probe found the a pin on the ECU that runs on and off with the light switch.(behind glove box - passenger side) then I ran a wire from the engine compartment to the bad ground plug on the where the relay plugs in. I tucked the wire into the cab and spliced it on to the green ground wire on the ECU. It only makes the ground when I turn on the switch at the stalk.

It may not be perfectly right, but I now have headlights and high beams.

Everything else is working.

I used two strands, green and white from some CAT6 I had lying around.

If anything blows a fuse, I will let y'all know.

The picture isn't perfectly clear but I just tagged onto the green wire.

Thank you for your support!

 

Okay, I understand. But the wire I spliced to only lights the probe when the switch is rotated on for headlights. So yes I bypassed but, not directly to ground. It is a green wire, can't be sure it's #20 but I am sure it is a part of the headlight circuit.

I looked for pin 20, green wire, but this worked.

What I don't understand is, why didn't it show on the dash that the lights were not working?

And I guess I will find out soon when one of the bulbs burn out, if the dash will tell me now. Bulbs were most likely touched while working around this one. I have new ones for when they fail.

 

I put the wire to the upper side (closest to the windshield) of the relay, as the other had had voltage.
The lights are not always on. They are working on the switch.
And okay about the lights on the dash, but many of the cars I've seen lately tell you of a headlight out, sometimes even a specific headlight being out.
So headlights weren't working at all, but still a normal light bulb indicator in the dash saying all is good.
So I figured lack of a light on the dash might indicate there is a problem. Aparently it only indicates the switch for the light is on.

First Prius for me...

Thanks again for being there. And I am happy to have lights on again.

 

I am thinking old school, like when you have a blinker out, the blinker doesn't flash or flashes quickly...