2002 Hyundai GX350L Park Tail Lights Do Not Work

This 2002 Hyundai GX350L came in with the complaint that the front park lights, rear tail lights and dash illumination lights all do not work. The first thing that I noticed was that there was no click of the tail light relay when the switch was turned off and on. I found and tested the taillight fuse in the underhood fuse box. It was both good and powered.

After consulting a wiring diagram I shifted my efforts to the interior of the vehicle. From the look and feel of everything, someone else had been here recently. I needed clear access to the interior fuse/relay box and that meant that the under dash panels had to be removed. There are retaining screws at each lower corner. There are two screws on the underside of the hood release handle. All are phillips head.

There is one screw on the underside of the park brake release handle. After the screw is removed the handle can be slid off. This reveals the two screws that hold the panel to the park brake handle bracket.

The switch panel has to be carefully pried out so that the hidden screw can be removed. There are latches on each of the switch harness connectors that have to be pushed in before the harnesses can be pulled from the switches.

The panel will then pull free of the dash with the minor exception being around the ignition lock cylinder. The panel will need to be pulled and wiggled  in order to release the hidden push clip that is located just to the left of the lock cylinder. The panel will also catch slightly under the edge of the panel just above the lock cylinder. I had to use a small screw driver the free the trapped edge.

Now the interior steel panel has to be removed.  There are two  recessed 10 mm nuts along the upper edge of the panel. One on either side of the steering column.

There are two 10 mm bolts. One on either lower corner of the panel. After all fasteners are removed the panel will pull free of the dash. The right hand side takes a little maneuvering around to free it from the surrounding plastic.

The parking brake assembly has to be re positioned out of the way in order to gain better access to the fuse box and it’s rear wiring connectors. There are three 12 mm nuts that hold the bracket to the vehicle. Two along the firewall edge and one above. The lowest one on the firewall side required a swivel socket and long extension. One could use a wrench but it would be a little more difficult.

I was of course doing this repair for the first time and had to fully remove the fuse box in order to determine the actual cause of the problem. Note the over heated connector that I am holding in the next picture.  I realized later that I could have seen  and repaired this without removing the fuse/relay box. Hind site is 20/20.

I called the local Hyundia dealership to find that the fuse box would have to be ordered and would cost $760.00.  The customer did not have the money to replace the fuse/relay box along with the needed labor to diagnose, install and repair the harness connector. I did some extensive research in the wiring diagrams and found that the single damaged wire only supplies power to the #30 and # 86 relay terminals, nothing else. I gave the customer the option of installing a new relay harness and wiring it around the original location as should below.

I tested  and identified the relay terminals within the fuse/relay box. I then manufactured the harness assembly that you see in both the picture above and below.

The main reason I decided to wire around the fuse box can be seen below. Note the discolored large terminal to the left. The internal solder joint had been compromised and due to the construction methods used by the manufacturer, it could not be repaired without major disassembly.

The orange wire needs to be cut and the matching wire from the harness will be spliced into the wire half that is part of the harness.

Even though I know that the orange wire that is still in the harness connector is dead, I feel compelled to cap it off with a piece of heat shrink tubing. One important note for anyone attempting this repair is that although the wire is orange in color it appeared to be brown due to the heat damage.

When reassembling the under dash components, I realized that testing and repair can be done without removing the fuse/relay box.  The parking brake assembly has to be loosened and repositioned to the right to gain access to the wiring. If you will click on and enlarge the following picture, you should be able to see that the orange wire is the very top wire in the wiring harness. I would recommend a quick test of the orange wire to confirm that battery voltage is present at all times before proceeding with this repair.

I used a wire tye to attach the relay harness to the combination switch wiring harness. Notice that I labeled it so that anyone coming into this after the repair will know that this had been done.

The customer had mentioned to me that the combination switch had been replaced without fixing the problem before it arrived at my shop. I thought that I would check and identify the circuit and appropriate test for activation of the park/tail lights.  The control wire is the light blue wire in the center of the second row. It has a dark blue/white wire to the left and a green/yellow to the right. With the switch off there should be a nominal 1.8 volts present and it should go to zero volts when the switch is turned on. A continuity test would reveal an open circuit to ground with the switch off and full continuity to ground with the switch. I had a reading of 1.6 ohms resistance with the switch on. This wire connects the switch to the body control computer. Which in turn activates the park/tail light relay.

Another one done. It should be noted that the dash lights also started working again after this repair. Sadly most people do not know that engineers have designed a safety system into just about every modern automobile. If there is a power supply problem for the exterior park and tail lights power will also be disrupted for the dash lights. This way the driver will be alerted to a lighting problem without leaving the vehicle. Whenever you are driving and you notice that the dash lights have gone out you should pull over and check to see if the exterior lights are working.