If a headlight fuse blows, it could cause the headlights to stop working. Most headlight systems are also designed with a relay that
switches the power between low beam
and high beam headlights. If this relay goes bad, it could allow power to the high beams, but not the low beams.
Where is the headlight relay located?
Find the headlight relay closure:
Usually, it is
under the hood of the car
. The point where your fuse panel is most likely located. On the other hand, it may also be located inside the cab of the car, this would be the case if your car comes with an interior fuse box.
How do I know if my headlight relay is bad?
Headlights Don’t Turn
On
The most common sign of a bad headlight relay is headlights that don’t work. A headlight relay will typically fail in the open position, preventing voltage from reaching the headlights. If the low beam relay fails, the low beams won’t work.
What happens when a headlight relay goes bad?
One of the most common symptoms of a faulty headlight switch is
issues switching between headlight modes
. If the headlight switch fails or wears out it can cause problems operating the headlights. A broken switch may only work on certain modes, or may cause them to come on and off intermittently and erratically.
Which relay is for the headlights?
Check in your vehicle’s owner’s manual for the location of the
headlight closure relay
. It will most likely be under the hood of your vehicle where your main fuse panel is located. However, it may be located inside the cab of the vehicle if you vehicle is equipped with an interior fuse box.
Can AutoZone test a relay?
A relay can be checked with a jump cable
, a voltimeter, an ohmimeter or a test light. If the terminals are accessible and the relay is not controlled by a computer, the fastest method will be a jump cable and a test light.
Why do my headlights not work but my brights do?
2. Headlight Fuse or Relay is Bad. Like all electrical systems, the headlights in your vehicle have a
fuse in the circuit to prevent too much electricity from reaching the bulb
. There will also be a headlight relay that switches power from the low beams to the high beams.
Does one fuse control both headlights?
The first, and easiest, component to check is the headlight fuse. Depending on how your headlight circuit is set up,
there may be one fuse or multiple fuses for the headlights
. If you find a blown fuse, then replacing it may fix the problem. … You should find battery voltage on both sides of the fuse.
Why is only one of my headlights working?
You’ll need to replace the bulb, switch, or relay. If just one bulb
fails to work in
either high beam mode or low beam mode, it may be the bulb. Most headlight failures that are limited to just high or low beams are related to a relay or the high beam control switch.
How do you check a relay?
- Locate the relay you need to test. …
- The quickest and easiest way to test a relay is to swap it out with a known good replacement. …
- Grab a multimeter and set it to Ohms. …
- Leave the multimeter on ohms or continuity. …
- Energize the electromagnet coil with a 9-12V battery across the pins.
Why do my headlights burn out so fast?
WATER LEAKING INTO HOUSING
Any signs of condensation inside the headlight housing may indicate that water is leaking into the housing. Water and electricity don’t mix and any condensation may cause a short circuit leading to failure. Also, any condensation coming in contact with a hot bulb may cause the bulb to break.
How do you diagnose headlight problems?
- Turn on your headlights. Replace whichever headlight bulbs do not turn on. …
- Open the engine compartment fuse box. Pull the fuse that operates on the non-functioning headlight circuit. …
- Connect the negative lead of the voltmeter to the negative terminal on the car battery.
What does HDM relay stand for?
If you know how to replace the HDM which stands for
Headlamp Driver Module
, is # 46 in the fuse box compartment on left side of engine.
What does H LP mean?
H-LP stands for
headlamp
, guessing the CLN might mean cleaner, as in a headlamp squirter or a wiper system neither of which are US Spec.
Why relay is used in headlights?
By using a relay we
move the high current switching away from the headlight switch so that the switch only sees a small current
– in the range of a few thousands of an amp. This solves part of the problem. You will need two relays – one for low beam and one for high beam.
