Headlights, tallights and DRLs not working properly

1999 CHEVROLET PRIZM
108,800 MILES • 1.8L • 4 CYL • 2WD • AUTOMATIC
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ZHILL93
  • MEMBER
  • 20 POSTS
For some reason I can’t turn my daytime running lights on and for some reason my headlights and taillights cut on automatically at night even when I have switched them off. I can’t turn them off for some reason.
Apr 17, 2022 at 11:59 AM
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KASEKENNY
  • ✓Experienced Mechanic
  • 18,907 POSTS
If both the DRL and head lamps are acting up, then the likely cause of this is a switch issue. The reason is, each of these have separate relays and even a DRL module.

So, we need to prove this out by checking the voltage when the headlights are off coming from the switch and the dimmer relay.

I assume you will have voltage on the dimmer relay, so we need to check and find out if the DRL module is grounding this relay on the white and red wire.

https://www.2carpros.com/articles/how-to-check-wiring

I am attaching the wiring diagram below but if we do then the issue is the DRL module has failed and is causing both these issues.

Let me know if you have questions. Thanks
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Professional Diagram for 2CarPros Members
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Apr 18, 2022 at 10:02 AM
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