Basically EVERY Printed circuit board used in Automotive Electronics is Wave Soldered during assembly.

Do you think they do this in Stuttgart? Or Goteborg? or Torslanda?...

Try Matamoros, Calexico, Hermosillo. Try shaving pennies when subbing out the contracts to your suppliers and you gt Mexican Wave soldering and poor workmanship.

Bosch, Hella and AC/Delco all went to Mexico 20 years ago and all found out 3 year later they had assumed Detroit/Stuttgart/Torslanda levels of QA/QC existed in Mexico...they didn;t.

Get a 15 watt soldering iron and some basic lead free solder in 1/8th in diameter and open te relay or assembly and fix it in 10 sec by reheating the joint until the excess flux burns off and the solder flows well and let it cool.

Bob's your Uncle it works like a charm!