Every car fuse box comprises different fuses and relays with an acronym to give you a clue of what the fuse or relay is for. If you open your fuse box, you will see acronyms like MG/C, ST, EFI, DIM, HDLP or H-LP, etcetera.
In today’s article, I will explain HDLP fuse meaning, how it works, common issues, and how to replace it if it blows up.
What does HDLP mean in the fuse box?
Generally, the HDLP relay fuse stands for the headlamp fuse. It is a device that breaks current to protect the headlamp from overcurrent by overheating and breaking a fusible part to prevent the current from passing.
HDLP wash fuse refers to the headlamp wash fuse. Vehicles with automatic headlamp washers have an HDLP wash fuse that regulates the current that gets to the system. The fuse powers the washer pump. On most vehicles, the HDLP fuse is typically a 20A found inside the fuse box on the left engine compartment.
According to some users, the HDLP can be a 15-amp fuse located under the edge of the dashboard and may be marked with HDLP #1 and #2. So, it’s important to note that the location and amperage of the HDLP fuse varies from vehicle to vehicle. I recommend you consult your owner’s manual for a specific answer for your car’s HDLP fuse.
Now that we have seen the HDLP meaning, let’s see how it works.
How does an HDLP fuse work?
As explained earlier, fuses are designed to break a fusible circuit if too much power comes through them. This protects all the components on the circuit.
If the HDLP fuse blows up, it could cause your low and high-beam headlamps to stop working, depending on how your headlamp circuit is set up.
On most vehicles, the headlamp circuit has four relays, and the right and left headlamps (both high beams and low beams) are fused individually. If there’s an overcurrent or power surge, both the high beam and the low beams will stop working if the fuse HDLP fuse blows.
If your vehicle has two headlamp fuses (HDLP #1 and #2) and one blows, the lights on the other fuse will be working unless the second fuse is affected.
Common issues with HDLP fuses
Issues with the HDLP fuse are not common and do not get much attention as they do not blow more often than other car fuses. However, I have a few reports from different people about their personal experiences with an HDLP issue.
Someone reported checking his trunk and saw a fuse 30-amp fuse labeled HDLP wash. When checked the owner’s manual, the manual said the fuse was for a headlamp washer. But there’s a missing switch. The thing is, this feature does not have a switch. In several cars that feature the headlamp washer, the washer typically cycles when you use your windshield washer.
In other instances, someone who drives a 2012 Pete 384 has an issue where the rocker switch lights on when he turns on the headlamp. The headlamp will stay up to 30 minutes before coming on. According to the user, the car will project HDLP fault on the dashboard, and the lights will flicker while driving.
In another report from a user, there was an HDLP fault message showing on the dashboard, but after checking the bulbs and pigtails, everything appeared good. But still, the headlights and clearance lights are still out.
However, the HDLP fault only appears when the user switches on the high-beam headlights. After inspecting all the connectors, everything looks fine and intact. The low beam on the driver’s side starts blinking occasionally. After a while, it starts blinking consistently, and the high beam is completely out.
How to test an HDLP fuse
Testing an HDLP fuse is a fairly simple process that you can do at home with little or no tools. You can just do it by swapping the HDLP fuse with another fuse of the same amperage. But to do proper testing, you’ll need at least a working test light.
Method 1: Swap the HDLP fuse
This first method is pretty simple and easy. All you have to do is locate the HDLP fuse in your fuse box and swap it with another fuse of the same amperage. Now, check if that solves the headlamp problem. If it does, you have a blown HDLP fuse that needs replacement.
Method 2: Using test light
This second method involves testing the HDLP with a test light. Grab your test light and ground it to the negative battery terminal or metal surface on your car. If you choose to ground the vehicle anywhere aside from the negative battery terminal, then it must be on any unpainted metal surface.
Once connected, poke the tip of the test light on the positive battery terminal to ensure the tester is working properly. If the tester shines light when you connect it, it means the connections are okay.
Now, remove the tester’s tip from the positive battery terminal and stick it into one of the holes on the HDLP fuse. The tester should light up once you poke the tester into a working HDLP fuse hole. The fuse is likely blown if the tester does not shine light when you poke it into any of the holes.
Kindly note that you don’t need to turn on the ignition or start the vehicle before running the test. If the fuse is bad, the only feasible solution is to replace it.
How do you Replace an HDLP fuse?
If you suspect your HDLP fuse is bad and a test confirms it to be true, then you have to replace it. Replacing a fuse is one of the most common DIY fixes you can do in your car.
Here are the simplified steps on how to replace an HDLP or any other fuse in a car.
- Park the car on a leveled ground
- Turn off the engine
- Open the fuse box in the engine bay and locate the HDLP fuse
- Unplug the blown fuse and replace it with a new one
- Close the fuse box, and the headlamp should be working now.
The importance of HDLP fuses in vehicle safety
The HDLP fuse is an essential electrical component that protects the wiring, headlamp bulbs, and the washer pump from damage due to the overload of electricity.
Basically, HDLP fuses protect the headlamp wiring, headlamp pumps, and the washer pump from overcurrent, short-circuiting, overheated and melted wires, and fire outbreaks in the vehicle. If short-circuiting happens without the HDLP fuse, it can cause serious damage, fire, and even small-scale explosions.
If you have been reading to this point, you will know that HDLP fuse meaning on Chevy Silverado, HDLP fuse meaning on Ford, and on any other car model are the same. HDLP refers to the headlamp fuse on all cars. This article has also outlined common problems related to this component and how to test and replace the fuse.
If you keep having persistent problems after trying the guide in this article, contact your mechanic to have a closer look. The technician will run a thorough diagnosis and rectify the issue.