Headlight Control Issues (LSM) 2003 XC70

[djdadcore]

I’m having some issues with my headlight control module (LSM) on my 2003 XC70. I recently had my instrument cluster repaired. Prior to repair, it was loosing backlight intermittently along with the function of the headlight control. Sometimes it would not work at all and sometimes after driving for 30-45 mins it would suddenly snap to and work. After getting my cluster back, it is still not working more than it is. I followed a tutorial to reflow the solder on the board to all the problem areas (please forgive my amateur work.) Since doing that, it will inconsistently work and when it does work the lights on the module and all buttons work, the dash cluster will brighten and the radio will brighten. I can take the whole module apart and plug in just the bare board and it will work, then I can assemble it and it will work, but once I put it back together and reinsert it into the dash it will work. But if I turn off the car, walk away for 15-20 mins and come back, it will not work. As far as I understand, the module sends data signal from the CAN bus and the relay is integrated to the module. I really would love to fix this module to avoid waste but I’m guessing I just need a new module? What does everyone think?

[djdadcore]

Here is a photo of the board post repairs

[DavidE7]

Were you successful at fixing the PCB?

The only option I know is to reflow the solder on all the electrical components. Get electronics flux and apply a little to each solder joint before touching with the soldering iron to keep the solder joints pretty. I have found that replacing the headlight switch module is a lot easier and quicker (if you have a local pick-n-pull junkyard) than trying to get all the very small solder joints fixed. A junkyard module is also the lowest cost way to get replacement light bulbs. Use a link free cloth and rubbing alcohol to clean the marks near the transistor in the center-left of your picture. I found an improperly soldered transistor in a Climate Control Module and a Driver Information Module. Reflowing the solder fixed both devces.