Is the Chabad custom to light a Yizkor candle?
Many are accustomed to light a Yizkor candle [i.e. Ner Neshama] for the days that Yizkor is recited. However, it is not necessarily the Chabad custom to light a candle for Yizkor. Indeed, the Rebbe and Rebbe Rayatz did not light Yizkor candles. [Practically, while some light a Yizkor candle as family tradition, and as stated in Luach Kolel Chabad, others follow the above mentioned custom of the Rebbe and do not do so, and there is no obligation for one to adapt to the traditions of others to light it. This especially applies if one forgot to light the candle before Yom Tov, and desires to light on Yom Tov.]
 See Aruch Hashulchan 514:19; Betzel Hachochma 4:29; Sefer Hachaim Hanitzchiyim 12:2
 Toras Menachem 56:231 “In answer to the question of why we are not accustomed to light a Yizkor candle as stated in Luach Kolel Chabad, the Rebbe replied “I did not witness that the Rebbe Rayatz did so.”; Hamelech Bemisibo 1:321 [printed in Shulchan Menachem 2:250]; Heard from Rav Leibel Groner; However, in Luach Kolel Chabad it says to light it.
 Toras Menachem ibid; Heard from Rav Leibel Groner
 See Admur 514:13; Michaber 514:5