How to Repair the Tail Light of Truck Bed

I was traveling from Idaho Falls to Nampa with my friend in a pickup truck. Suddenly a passerby told us that our truck bed tail light was not working, As we all know it is illegal to travel without a functional tail light, so we managed to repair the tail light as there was no garage nearby. So I have decided to help out other folks who have such problems with their truck.

How to Repair or Diagnose Non-Functional Tail Lights? To repair the tail lights, we have to open the tail light from the truck bed and change the fused bulbs. If all the bulbs are Okay, then clean the bulb contacts with a cleaner solution. If then also the tail lights do not work; change the wire harness connected to the tail lights.

Steps to Repair the Tail Light of Truck Bed

Now let’s deep dive into the process described in detail step-by-step to repair the tail light of truck bed.

Removing the Tail Lights from the Truck Bed

This process is typical for all pickups. We can remove the tail lights from truck bed by unscrewing a screw located near the tailgate lock. Use the appropriate tool to open this nut and gently pull out the tail light. If you feel something is wrong; Its time to read the user instruction manual that came with the pickup.

Removing the Defunct Bulb out of Bulb Housing

Gently pull the holder from the tail light housing and replace it with a new and tested one. Then gently put back the holder in the bulb housing while keeping track of the grooves around the holder. Then check the bulb by applying the brake. If it works, then congratulations! We have successfully fixed our tail light.

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What if the Tail Light does not Glow Even After Replacing the Bulb?

As we travel with our pickup truck to various places in various weather so the contacts on the bulb holder and the bulb metal contacts may pick up corrosion due to changing temperature and moisture. Corossion problem is more prominent if you drive more in the coastal region. Now If we have the tail light opened already, take some rust removing solution from the local hardware store like WD-40 and some fine sandpapers. Remove the corrosion from the contacts by spraying with WD-40 and then let it dry. Properly polish the contact surface with sandpaper. Now put back the entire assembly as we have removed from the housing. Then again test the tail light if it glows.

What if the Tail Light does not Glow Even After Cleaning the Contacts?

If the tail light does not shine even after cleaning the contacts, then we need to do some advanced diagnostics for any electrical faults. We need a multimeter for this job and of course glove; it’s better to be safe! We need to set the multimeter in DC voltage measurement mode for automatic range selection multimeters. For standard multimeters, we have to select the DC voltage range to 20 volts. 

Now apply the brakes again and measure the voltage between the terminals by putting the multimeter probes in between the terminal and any exposed bare metal part of the vehicle. If the reading from the meter shows between 12v to 14v, then the wire harness connecting the tail lights are okay, we have to re-clean the contacts again correctly.

If the multimeter does not show any voltage, well it is a nightmare situation. We have to replace the wire harness of the pickup; which is preferably an advanced job. We have to get the original wire harness by visiting the manufacture parts store or other authorized parts dealer.

Do not cheap out in purchasing the wire harness. Cheap quality may get damaged well before time and can cause a fire in the truck too. After obtaining the wire harness, it’s time to put it inside the car, which should be carried out by an authorized technician.

Can I Replace My Damaged Tail Light Wire Harness?

Yes with some good technical know-how about electronics and tool experience you can replace the wire harness on your own. We don’t have to visit the garage to get it repaired. Although there is no universal way to follow to replace the harness, still the majority of the truck have their tail light harness extended from underneath the dashboard up to tail lamp under the truck bed. We need protection gears too and a lot of patience to get it replaced on our truck.

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But Wait! My Truck Has LED Tail Lights, What Should I Do if it Fails?

Most modern cars come equipped with led tail lights aka LIGHT EMITTING DIODE. These are the most efficient and brightest lights used on modern automobiles. This puts less load on the battery. These last long as they are totally solid unlike tungsten filaments in the regular bulbs. This LED is not replaceable individually; they are part of the entire light assembly. We have to replace the entire tail light if LEDs stop working. The reasons include surge from the alternator, a high voltage from the power system, improper use of output sockets inside a vehicle and such. LED tail lamps are very expensive to replace or repair.

We have to visit the authorized dealer to get one replacement for the tail light. Then we have to remove the dysfunctional led tail lamp from the truck bed by using appropriate tools. Unscrew the screws near the truck bed tailgate locking mechanism and then gently pulling it out. Then detach the connections from the led tail light and connect the new incoming functional tail light.

We have to fix just as we removed the older one. We have to be careful not to scratch the glass of an LED lamp or drop it. Although it has solid-state technology like LED chips; Inside the minuscule LED chips there are tiny gold wires which connect Anode (Positive electrode) to the cathode (Negative electrode) when current passes along the chip which emits light; sounds simple huh! Please handle the light with care. On dropping this, the gold wire may get disconnected rendering the light useless.

Related Questions

Can I Upgrade My Tail Lights to Aftermarket LED Lights?

Yes and No! LED lights have a much longer life up to 50,000 hours if driven by optimum current and voltage. Some older trucks may not have good power regulators and surge in the power system. Replacing filament bulbs with LED ones are too risky for such a situation. We have to find for a replacement LED bulbs in the market which have inbuilt power regulators which can bear the surge, over voltage or under voltage situations. Normal incandescent lights have 2500 to 5000 hours only. These bulbs can also sustain over-voltage, under-voltage and surge conditions better and longer than LED bulbs.

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The main disadvantage of LED tail lights is they need to stay cool to prolong their lifetime. So while purchasing for replacement LED we need to be careful about the shape and size heatsinks the LED tail light module has got. Some states have regulations for the luminance and color wavelength for tail lights. We need to make sure that we follow all the rules laid by states and federal government bodies. There is also drop-in replacement LED available in the market to replace the bulbs in the older trucks. Again we have to take care of the heat sink sizes of the bulbs prior to purchase.

Should I Use Tail Light Protectors?

Yes, we can use tail light protectors. The protectors are made out of either steel, Stainless steel, Chromed steel or plastic. It is always good to have protected tail lamps. The glass of tail lamps is relatively fragile. Any flying gravel from passing vehicles will crack it for sure and don’t think about going offroad without tail light protectors. But we have to make sure that the protector must not cover more than 70 percent of the total area of the tail light.


Broken tail light not only gets you in trouble with cops but could also be dangerous, especially when you are driving at night. The aforementioned steps should get you through the trouble if you can pull it off. However, it is also necessary to carry replacement parts in your toolbox. It’s also a good practice to check your tail lights, headlamps, turn lights, and other components before leaving your home.

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