Can I Use the Margin from Pledging to Trade If My Cash Balance Is Zero or Negative?

Yes, you can use the pledged margin to take new positions, even if your fund/cash balance is zero or negative.

However, as per exchange rules, at least 50% Of The Total Margin requirement must be in Cash. If the required cash margin is not maintained, the shortfall amount will attract an interest charge of 18% per annum until the deficit is cleared.