This combination as the name suggests is formed by conjunction of the chandala ( outcaste ) planets Rahu Ketu with the Guru ( priest or teacher ) .Jupiter chandal dosha is also known as Guru Chandal Dosha because of Jupiter is also known as Guru and has a major role in this dosha .Guru dosha is also likely to provide malefic results for the native if it is conjunction with or aspected by Saturn, Rahu or Ketu in the natal chart. This is most malefic for the native but also beneficial in some cases when the Ketu and Guru are in the benefic position in the natal chart. Different effects of position of the Guru Chandal Dosha obtained in the different house of the birth chart.
It has been seen as a negative combination by ancient Rishi because the native becomes too materialistic especially in the case of Rahu conjunction of Jupiter. The conjunction of Jupiter with ketu is supposed to provide wicked tendencies even when the native is born in the most decent family because of this dosha. The native is selfish and sensual. They are flirtatious in nature. Female natives lose their partner early either by divorce or becoming widow.
However this combination can give a generous and highly philosophical nature when placed in signs like aquarius and pisces.
If Jupiter becoming malefic can cause major health problems such as Jaundice, liver problems, high blood pressure , difficulties in making decision, hindrance in education, negative thinking etc.