What's up folks. My 1997 4Runner SR5 4x4 doesn't have the headlights wired to the ignition. They are always hot, and both me and my wife leave them on sometimes. No cab alert noises either.

Anybody have experience with handling this wiring so that the headlights turn off with the ignition? I'm decent with wiring, and have some knowledge of relays and other types of switches and connectors.

Where would I start... with wiring in a new relay, or trying to tap the headlights into an existing relay connected to the ignition switch?

 

FYI, one of these days I am going to just jump in there with my clamp meter and figure out what's hot and what's not, and how I might unravel the mystery. I just wanted to see if anybody could give me a head start!

 

First off, a clamp on ammeter, or ampmeter, isn't exactly the right tool for the job. You need a multimeter. A meter that can read Volts, both AC and DC, and several different ranges of resistance, or Ohms. They come with 2 leads, a red one, and a black one. You plug the red one into the + for Volts, either a/c or d/c. For ohms, polarity isn't important, other than testing diodes. Such meters are readily available, at places like Harbor Freight, or most auto parts stores, like Auto Zone, or Napa.

Such meters can also read amps, but only small amounts of current flow. That's where the clamp on comes in handy. They can read much higher scales of amps.

Now, having said all that, what's hot when, isn't exactly what's important in this case. Toyota has a wonderful habit of using switched grounds. In other words, when you turn your lights on, you switch the ground they need into the headlight's circuit, you don't switch voltage onto the headlights.The voltage (battery voltage) is always on the headlights, but when you switch them on, you apply a ground, so current can flow. They did this for 2 reasons. First, that way you have headlights available in case the engine cuts out for some reason. For some reason the COR shuts the fuel off to the engine, for example. Second, Toyota electrical engineers, because it's the way the Japanese have always done it, switch grounds into and out of a circuit, rather than hot, as Americans do. If you were to check the switch, let us say, with your multimeter (the RED lead, volts DC, 20 volts scale), you would read the battery voltage, let's say +12.9 VDC on it, between the switch and ground, let us say a random chunk of the firewall with no paint on it. When you turn the switch to ON, low beams, you would now read something close to 0 VDC, because the terminal of the switch you are reading is now the same potential as the ground point you chose. You will read something, due to various minor resistances in the circuit developing a small amount of voltage to ground.

Finally, if I'm not mistaken, and your 97 is very similar to my 99, your lights have a 2 hour timer on them, so they shut themselves off after two hours of the lights being on, with the engine shut off. It works, too, trust me. Also, that's not long enough to drain a battery, in good condition, to the point it will no longer start the engine. Again, trust me on that. I've left my lights on on more than one occasion.

Does all my rambling help at all?
Pat☺

 

Thank you! Yes, I do own a multimeter and a clamp meter, and understand the functions of both. I was only referring to the clamp meter initially to suggest I would use it to determine which wires had current flowing as I turned the headlights on and off. I guess I had imagined I might need to assess which wires were the headlight wires in the cab if I needed to add a relay.

Well, thank you! This changes the whole thing. If the headlights turn themselves off after 2 hours, then I won't worry about it at all. My neighbor usually sends me a text message within an hour of leaving them on, so maybe I've never waited long enough to see what would happen.

Thanks 2ToyGuy

 

Finally, if I'm not mistaken, and your 97 is very similar to my 99, your lights have a 2 hour timer on them, so they shut themselves off after two hours of the lights being on, with the engine shut off. It works, too, trust me.

WHAT?!?!?!? NOOOO WAYYY.
Is that true? I have owned a 3rd gen for 20 years and have never heard that.

 

I don't think it's true. While @2ToyGuy sounded sure, it does not seem like my '97 4Runner is turning its headlights off after 2 hours. I am pretty sure today that mine are still not doing that, so my original reason for this post is still relevant for me, and that is regarding the idea of wiring in the headlights to the ignition. I'd be interested to know if anybody else can verify that the early 3rd Gen 4Runner does this with the headlights.

One day soon I'll leave a battery charger on my 4Runner battery and then leave the headlights on. Then I'll set a timer and go back and check.

 

One way to be absolutely certain: Do the test you're considering. Turn off the engine, with the lights on, and come back after something more than 2 hours. That will tell the tale.

A thing to check also: Read the owners manual. It specifies that system exists. But th test is the certain way to verify whether it's true or not...

Have funQ
Pat☺