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Headlight failure

Tiny
GKBLOOM
  • MEMBER
  • 2000 TOYOTA COROLLA
  • 1.8L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 170,000 MILES
When I start my vehicle headlights comes on for ten seconds and then turns off if the light switch is in the "off" position. If the light switch is in the "on" position the headlights will not come on at all, almost like the headlight switch has some faulty contacts? Is the problem in the switch or maybe the ECU body module?
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Wednesday, June 12th, 2019 AT 11:09 AM

12 Replies

Tiny
SCGRANTURISMO
  • MECHANIC
  • 4,897 POSTS
Hello,

This could be a problem with the headlamp switch itself. But to be sure if it is or not, I have included for you in the diagrams down below the factory diagnostic tests for the headlamp switch for your vehicle. Please go through this guide and get back to us with the results. We will then proceed from there.

Thanks,
Alex
2CarPros
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Wednesday, March 31st, 2021 AT 12:56 PM
Tiny
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Alex,

Thanks for the information and I will begin to check this out tomorrow. When checking the light switch function do you need to check from chassis ground back to the terminals on the switch plug or is it better to place the meter leads across the terminal pins?
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Wednesday, March 31st, 2021 AT 12:56 PM
Tiny
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Hello Alex, The wiring diagram for the light/turn signal plug that you sent does not quite match up to to my plug. I have 8 pins on top row and 8 pins on bottom row and yours shows 8 on top and 9 on bottom. I'm not sure if there is a different schematic you can provide for a 2000 Corolla?
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Wednesday, March 31st, 2021 AT 12:56 PM
Tiny
SCGRANTURISMO
  • MECHANIC
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Hello again,

Both of my reference guides show a 17 pin connector for all models of the Corolla for 2000. I have included the diagnostic test procedures from my other reference, as it is a little more comprehensive. Please go through this guide and get back to us with what you are able to find out.

Thanks,
Alex
2CarPros
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Wednesday, March 31st, 2021 AT 12:56 PM
Tiny
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Hello folks, here is a picture of the plug that only has 16 pins and not 17 pins. Any ideas on the pin out of this 16 pin plug?
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Wednesday, March 31st, 2021 AT 12:56 PM
Tiny
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Hello again,

How many pins does the female harness connector to the switch have?

Thanks,
Alex
2CarPros
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Wednesday, March 31st, 2021 AT 12:56 PM
Tiny
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Alex,

Female connector has 16 Pins as well. There are nine wires hooked up (see diagram). When I plugged the switch back (key turned on) in I was able to measure some of the pins (see diagram). I assume the two smaller pins I could not measure would be turn signal function? Is it possible that the two larger pins (on top) I could not measure might be for normal headlight function. I'm not sure what the pin that has 10 volts on it does, the voltage did not change when ever I turned any of the switches (headlight/turn signal) on or off.
Can you provide any wiring diagram from headlight/turn signal switch? Not sure if my car has a DRL Relay or where it would be located.

I labeled the picture below and took measurement from battery ground to the pins. I making some assumption's on what the pins are labeled based on turning on and off the high beam switch and turning the light on and off. The turn signals do work for another data point.
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Wednesday, March 31st, 2021 AT 12:56 PM
Tiny
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Hello again,

I have included the exterior lighting wiring diagram for your vehicle in the diagrams down below. I hope that this helps. Please let us know what you can find out.

Thanks,
Alex
2CarPros
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Wednesday, March 31st, 2021 AT 12:56 PM
Tiny
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Hello Alex,

I finally had some time to work on this problem and thanks for the schematics. I did some voltage checking and noticed that on pin 2 of the DRL relay there was approximately 14 volts with the lights off so I ran a ground wire from pin 2 on the DRL relay back to the ground battery terminal and the lights did come on. The Light switch on the steering column has no affect on turning the lights off with the ground wire from pin 2 on DRL relay to ground. The high beam indicator on the light switch does work and when the car is turned off the lights do go off. Left and right signal also works okay

Any ideas on why the Light switch will not turn the lights off now that I have DRL pin 2 jumped to ground. I measured the current flow from pin 2 to ground and it is about 8 amps which seems about right since the headlights were on.
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Wednesday, March 31st, 2021 AT 12:57 PM
Tiny
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Hello,

Okay, I do not see the relay you are talking about. Relays are electromagnetic switches that use an energized coil to "flip" the switch and that allows electricity to flow to circuit's load. A four pin relay consists of two pins, usually pins 88 and 86, that control the coil, one pin connects to a switched power source, i.E. A fuse that is either hot in run or start, and the other hooks to a ground, so when the ignition key is turned to either start or have the vehicle running the coil will be energized and the switch pulled closed, and only then will the coil be energized. The other two pins, usually pins 50 and 87, are hooked up to a constant power source and the other to the load or the device you want powered, so that when the coil is energized, the switch is pulled closed and the device that you want power to is now powered. I am not sure what pin you mean when you say pin 2, but I am going to assume that it the ground side of the coil, and that it usually will run to a control module and that the control module usually provides ground causing the coil to energize. You have just cut this module out of the equation and provide the relays control side with ground making the switch close and power to be provided to the headlights.

Thanks,
Alex
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Wednesday, March 31st, 2021 AT 12:57 PM
Tiny
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Alex,
Providing a new ground to the contact side of the relay did fix the problem.
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Wednesday, March 31st, 2021 AT 12:57 PM
Tiny
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Hello again,

That's great. We love it when you get the problem fixed. Great job, and please, feel free to ask should you have any other vehicle related problems.

Thanks,
Alex
2CarPros
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Wednesday, March 31st, 2021 AT 12:57 PM

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