Hello. The headlights stay on all the time & wear the battery down. I’ve replaced the DRL module with two new modules & neither fixed the problem. I even examined the headlight switch (some burn up at the switch), but this headlight switch & wiring look new. I even took the headlight switch out & the headlights still stayed on. I made sure that the new modules were grounded to the chasis properly.
The problem might be with the multifunction switch. With the headlight switch removed the multifunction switch is still provided with power. One of the functions of the multifunction switch is to turn the headlights on when you want to flash-to-pass. So it could be that the flash-to-pass contacts in the multifunction switch are stuck closed causing the headlights to remain on.
Tester
Are they on High or lowered “DRL” intensity? Could be Parking brake switch or ignition switch.
Ignition switch?
The headlight circuit doesn’t pass thru the ignition switch. The headlights can be turned on without the ignition switch being on.
Tester
A shorted or fault ignition switch can keep the DRLs on.
Remove the headlight fuse. If the headlights turn off the problem is with the multifunction switch.
Tester
Tester, that should be correct. But there may be more to it.
In my car, I can turn the headlights on without turning the ignition switch on, but if I have the headlights on and turn the key off the lights stay on until I open the door, at which point they go out. Even in my case, you can see from the attached schematic that the headlight circcuit goes through the the contacts of the headlight relay, the coil of which is energized by the “integration relay”. I haven’t looked up the “integration relay”, but the point is that without schematics it’s hard to make assumptions.
You’re comparing apples to oranges.
You keep putting up those Scion diagrams as if all vehicles are wired the same. They’re not. If they were the diagram would read Toyota, GM, Ford, Honda, Nissan, etc…
The Taurus headlight circuit looks nothing like that.
Tester
I used it to illustrate the point that these circuits generally aren’t as direct as one would think. They often go through the contacts of various relays that allow functions specific to that car to happen. I use my stuff as examples to illustrate points only because thay’re the only design drawings I have access to.
I realize that all cars aren’t wired alike, but I don’t have access to schematics for the OP’s car. If I did, I’d post them. If you do have access to them, post them and perhaps we can track the problem down.
I do have access to the factory wiring diagram for OP’s headlight circuit. But I can’t post them here for two reasons. One, Mitchell-On-Demand doesn’t allow the user to transfer a file from their website onto the internet. And second, even if I could, I wouldn’t because it violates copyright laws.
Tester
You’re right and I respect your integrity. In my case I’m under no such constraints with the Scion drawings.
I do hope you realize that I only post these Scion documents to illustrate points and know that cers vary, especially in their approaches to wiring. I’ve always felt that a picture is worth 1,000 words.
After looking at some data on your vehicle it shows your should have a autolamp headlamp relay and a module called a light sensor amplifier which controls the relay. I would first suspect the module is turning on the relay rather than a having a faulty relay. Try to locate these two items and remove the module from the circuit and see if the problem clears doing that. There is another module that can also turn on the relay called the Anti-theft personality module. If removing the light sensor module doesn’t solve the issue then look to that one next.