Tailgate Third Brake Light Fix
 

Hi guys, been a while since my last post, but we've had a 2002 V70 XC 2.4T since 2019 and recently, it has a third brake light that doesn't work. After some research, it seems that it's an LED brake light, so the whole assembly has to be replaced instead of a bulb. And of course, the part is discontinued with no aftermarket replacements available on FCPEuro or Rockauto, so the only option was a random light from Eastern Europe for $80-100 on eBay, or was it? I previously repaired the cluster/DIM on the car, so I thought I'd at least try to locate the failure point on this light.

I found that the weak point in the brake light is a little box that sends power from the connector to the LED strip. The connector sends power to a small PCB that has a resistor and a diode whose 2 pins go through a hole on the LED PCB into a box that flips the power 180 degrees to 2 solder pads on the PCB which then go to all the LEDs and associated resistors. I got the entire LED strip to light up after some finagling, so I found the connection of the diode's pins from the small connector PCB was poor and intermittent while on the desk and in hand. Looking at the PCB design, it would've been so easy to just have the diode's pins go straight through to the pads where it was needed anyway. Other than the (lack of) tension of the pins in the that box through the holes, there was only 1 tiny tab of the small PCB that slotted into a hole on the LED PCB while the other side of it touched a thin trace that I identified as a second potential point of failure, but it still conducted fine, so it was not rubbed through yet. I ended up going over it with clear nail polish to protect it in the future.

Either way, the way forward was clear, I had to re-establish a solid connection between that diode and the solder pads, so I bent the legs just enough to go directly into the pad holes while keeping the same spot as factory due to the housing cutout. I managed the bend, but accidentally kept my soldering iron temp too high, so the pads lifted. I attempted a repair on those using more noob unorthadox methods and also repurposed 2 USB wires as jumpers just in case it didn't work out and connected them to the nearest pads on the same trace.

Tested it on the bench once more, then installed in the car and it works in the driveway, so that's a plus. Only time will tell how long the fix holds up given that soldered connections are vulnerable to vibration, but I did use leaded solder, so that should help a bit. I just don't know why Volvo would use such a failure-prone method of connection for the power to the LED board. It would've been so easy to just bend the wires 45 degrees or so forward and have a substantially better connection than what they did from the factory. Sure it's a yay for modularity, but that part is part of the entire assembly which would get replaced as one anyway and thus doesn't help sustainability.

Taking the brake light assembly apart can seem daunting at first, but there are 2 tabs of the clear part that go into slots on either end of the black piece, just bend the black piece outward a bit with a small flathead and the plastic should yield enough to lift one side out and slide the other out after you've also gently cracked the 2 pieces apart longways across using your fingers and/or a small flathead. If it doesn't clip back in fully afterward, it's not a problem since it will be held against the tailgate and glass by 2 sliding clips and a push clip afterward anyway. Worst case, just use hot glue or superglue if you really want/need.

I couldn't find anything close to this level of detail with some searches on multiple forums a few days ago, so I'm posting my adventure in case it helps someone else in the same situation. I didn't take any pics during the DIM repair, but I made sure to take some this time.
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