Bad Headlight Relay Symptoms: 5 Common Failure Signs

Bad Headlight Relay Symptoms. Learn the common signs of a bad headlight relay so you can fix the issue before getting stranded at night. This video covers headlights not turning on, flickering lights, issues with high/low beams, lights staying on, uneven headlight brightness, dim lights, and relay clicking noises.
What this video covers
1. Headlight Intro
2. Symptom #1 - Headlights Not Turning On
3. Symptom #2 - Flickering Headlights
4. Symptom #3 - Issues with High/Low Beams
5. Symptom #4 - Headlights Staying On
6. Symptom #5 - Uneven/Dim Headlights
7. Symptom #6 - Clicking Noises
8. What causes headlight relays to fail?
9. How to test and replace a bad headlight relay
Disclaimer: This content is for educational purposes and should not replace professional advice. As an experienced mechanic, I aim to provide helpful insights, but I'm not liable for any damage or issues arising from the application of this information. Always consult a qualified mechanic for specific vehicle needs. Viewer discretion and responsibility are advised

[@samkitty5894]

When I turn my headlight switch to park, parking lights come on and the dash light up.
When I move the headlight switch to low beams, they don't come on, and my dashboard light go out.
If I pull on the high beam lever high beams come on but once I let go the lever, they go out.
All the fuses are fine. I assume at this point I am down to 2 possible culprits, headlight switch or the headlight relay. Here is another thing I noticed. With no key in the ignition, and with headlight switch to off position, if I manually pinch the contacts on the headlight relay, low beams come on.
I didn't know that the headlight relay is constantly powered, but not engaged.

[@adilux3]

I have a car with 1 dim headlight and 1 normal headlight when the switch is set to manual ON, but when I switch the headlight to auto, both lights are normal, would you know what the problem is? Is it the relay?

[@27THEBREEZE]

my drivers side headlight stays on on 59 plate astra

[@HonestMechanicChannel]

Hi. If the driver's side headlight on your 59 plate Astra stays on, it might be due to a faulty headlight relay, a problem with the headlight switch, or a short circuit in the wiring. To resolve the issue, start by checking and potentially replacing the headlight relay. If that doesn't fix it, inspect the headlight switch and the wiring for any signs of damage or wear. It might be necessary to consult with a professional mechanic or an auto electrician for a thorough diagnosis and repair.

[@Stevesguitartraveling777]

My driver side headlight on my 2007 Corolla just went out a week ago after replacing it in 2019 I noticed the highbeams were not working as well but after I change the bulb, I noticed the highbeams were working, but the low beam was not. I tried replacing the fuse, but that didn’t work. I’m not sure if it’s bad wiring and the dielectric grease on the bulb socket or it’s a bad relay.