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I have a couple of problems. First, I have a 2002 Toyota Tacoma pickup truck. I normally leave the headlights turned on all the time. When I turn off the ignition and open the door the lights automatically go off. When I start the truck, they come back on. Problem #1: My wife says I am crazy and the only person on the planet who would do such a thing. Problem #2: This morning the headlights came on all by themselves with the truck in the garage and they won’t turn off. When I went to get the newspaper, the lights were off. When I went to go to work the lights were on. No one had touched the truck. Also, I cannot get the lights to off - short of pulling the relay (which I did). Are these problems related?

My car has an auto off timer of 30 seconds, and I haven’t turned them “off” for a couple months, myself, though I do keep looking to make sure they DO turn off. So you’re not alone in that sense.

As for the problem, I’m not really sure what could cause it. Might be something in the relay, or the stalk, that has caused it to remain on.

Problem 1: No, you’re not crazy. There’s a reason cars have automatic headlights - people want and use them. That said, if your truck has HID’s you should not use this feature.

Problem 2: The truck thinks it’s on when it’s off. Likely suspect is the electrical part of the key cylinder. What’s the temperature like there? Sometimes electricals act up in the cold because the cold contracts, and therefore bends, wires, and so things which should not touch, do.

Thanks for the response. It is not that cold here. Outside is around 40F and my garage is around 50-55F. The problem only effects the headlights. The rear lights and dashboard all behave in a normal fashion. They go out when the key is turned off and the door opens. I checked the voltages on the socket for the headlight relay. There is 12 v across the relay (as there should be) and 12 v across the coil of the relay (meaning the light will come on if I put the relay in). So, I think the problem is somewhere between the circuit that senses the engine is off and the door is open and relay for the headlamps.

Your thinking about the relay control is most likely correct. There probably is a logic control module tieing to the relay coil for the lights and it may be faulty.

Checking some data, if you have daytime running lights, the headlight relay is controlled by the daytime running light module.

I took the pickup to my mechanic. He said it is the body control module. Furthermore, he said the price Toyota gave him for a new one was $1000. He was going to check further. Is the diagnosis reasonable? (I think it is. However, it is strange that only one small part of the programming goes bad). Second, do these modules always cost so much?

Your mechanic may very well be correct. I assume he has done the proper testing to verify the location of the problem. The new price he quoted you for a module like that is not out of line. They are very expensive so it is important that the trouble is diagnosed correctly. You should be able to order a refurbished unit from a auto store or get a used one from a salvage yard for a lot lower cost (less than half) if the trouble really is with the unit.

Here is just one example.

Thank you. I will talk to the mechanic about his diagnosis. I appreciate the independent advice.

Just a follow up. I took my truck to a mechanic. He determined the Body Control Module (or what Toyota calls the Integration Relay and it goes by several other names) was bad. Toyota Parts Dealer said a new one was $1000. I searched for something priced a bit more reasonable. I could not find one at any parts store. We checked several local junk yards. No luck. I was told these normally go bad when water leaks into the dash (typically from the windshield). I had no signs of water leaking – it was just an electronic failure(?) Not wanting to spend $1000 on an older truck, the mechanic gave me the schematics. The red-white wire out the Integration Relay runs to the headlight relay. So, I bought a $3 switch from the hardware store, cut the red-white wire, soldered the switch in. I now have an extra headlight switch, but it works great! I have to mechanically do what the Integration module used to do electronically. For $1000, I will flip the switch manually. Thanks for all the comments. I found a several instances of this problem on the internet, but could not find many resolutions.