The beacon of light that once heralded the Beacon Tower on the DUMBO skyline is kaput — one of nearly 100 construction problems cited in a $150 million racketeering lawsuit brought by the building’s condo board.

The RICO suit, filed last week in Brooklyn State Supreme Court, accuses the sponsors and the architect of committing mail fraud after obtaining a temporary certificate of occupancy.

To obtain the certificate, the engineer and architect signed Building Department documents verifying that fire stops were present when the board’s engineers later found none were installed, the complaint says.

Sales material for the 23-story tower at 85 Adams St. boasted of “a curvilinear louvered top … lit internally creating a beacon of light that will announce Beacon Tower’s position at the apex of the DUMBO community.”

But the light went out and there is no way to get to it to fix it, according to Steve Sladkus of Wolf Haldenstein, the lawyer for the board.

In addition, the complaint lists a litany of woes, including counter tops that are too high, parapet walls that are too low, improperly placed sprinklers, water leaks and unsafe windows.

The suit says that the sponsors were aware of the lack of required fire stops and other issues after the condo board commissioned a “top to bottom engineering report.” But none of the required sponsor amendments to the offering plan warned prospective buyers of construction defects, according to the complaint.

The suit names the sponsors, Jeshayahu, aka Shaya Boymelgreen, the Boymelgreen Family, AI Properties and Developments (USA), the sales brokers at Corcoran Brooklyn, the architects Cetra/Ruddy, two engineering firms and others. The parties either declined comment or could not be reached.