2006 Hyundai Tucson, Park Lights Stay On

This 2006 Hyundai Tucson came in with complaint that the park/tail lights would not turn off. As you can see below the park lights are on….


…. and the light switch is off.


Testing begins at the interior fuse box at the driver’s door opening. I am pointing to the right hand tail light fuse. Oddly enough the left hand tail light fuse is just to the right of the right hand fuse. I know it is a very small thing but wouldn’t you think that the left hand tail light fuse would be to the left of the right hand tail light fuse. But I digress.


I used a terminal that is the same size as a mini fuse blade terminal. Checking for power on the left side of both of the fuse slots indicated that power was being sent out from the tail light relay but remember the switch is off and the relay should be deactivated.



I also checked for power on the right terminal at each fuse slot. There was no power which was good thing. If there had been power on those two terminals it would have meant that the tail lights were on with the fuses removed and that they were being powered by an alternate power source.



A little bit of research showed that the tail light relay is built into the interior fuse box. There are a few screws that hold the under dash trim panel in place. All of the screws have phillip’s heads. One at each lower corner of the panel.


Two just to the rear of the hood release handle. The panel just unsnaps from the dash once the screws are removed. There is also a metal panel under this plastic panel. All of those fasteners have 10 mm heads. The data link connector also has to be removed from the panel by squeezing in the latches at either end of the connector.


There are three fasteners that hold the fuse block to the dash. Almost impossible to see so there are no pictures. Although all have 10 mm heads, two are bolts and one is a nut. The lower bolt at the forward edge is easy to get to. The upper bolt along the forward edge and the nut on the inside edge above the harness connectors are difficult to see and needed a swivel socket and long extension to remove them.


Once the fuse block is dropped down it is just a matter of disconnecting the harness connectors. There are also three harnesses that are secured to a metal strap at the lower forward edge of the fuse block. You should have probably disconnected the battery before getting to this point. I was scheduled to install a new fuse block that was ordered from a local dealer the day before. The customer and myself were both quite pleased when we were told the fuse box price was about $78 USD plus $8 USD for expedited shipping. Low and behold it came in and was the wrong part. They had ordered and sent the underhood fuse block instead. A few phone calls and a fax later and the proper part was identified but the price had changed to $358 USD and not in stock. Had to be ordered again.  Mind you that it is Friday afternoon on Labor Day weekend. Time to switch plans.


If at all possible I would like to fix the relay inside the fuse block. I started by removing all of the fuses from the assembly. Then I went around the outside edge of the fuse block assembly and pried the sides apart to release the latches.


A gentle wiggle and the cover was out of the way. The green circuit board assembly took a little more wiggling and prying to remove it from the plastic case.


I did not know which relay was at fault and it would be very dangerous to try and reconnect everything with the circuit board outside of the plastic case so I decided to remove all of the relay covers. The larger relay covers were not too hard to remove. I slid a curved pick under either side and flipped them up with little difficulty.


Of course I found no problems with the contacts on either of the two larger relays.


That meant removing the cover from the smallest relay. I had to pry along the edges of that cover in the same manner but in the end I had to break the cover in order to remove it.


I inspected the contacts of the smaller relay with a magnifying glass and could see the build up of material on one of the contacts. What happens on any relay is that when the contacts are move to the closed position there is an arc. When the arc occurs metal is displaced from one contact and usually transfers to the opposing contact. This happens many time in the life of the relay. A hill of metal fragments build on one contact. The other contact that is losing metal has a valley formed in the contact face. After enough build up is formed the two surfaces mechanically stick together. I am pointing to the contact are of the relay below.


I used a utility razor blade to shave the hill off of one contact and therefore removed the mechanical locking forces that were causing the contacts to stick together. It was that mechanical force that was keeping the park/tail lights on. I used super glue to add extra support to the relay covers that had been removed earlier.


In the end this Labor Day Weekend was going to be a little bit better for both me and my customer. They had their vehicle and my head hurt a little less.

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