Jimmy Kimmel's Band Leader Cleto Escobedo III Cause of Death Released

Jimmy Kimmel’s longtime bandleader, Cleto Escobedo III, died because his heart couldn't pump enough blood to keep him alive, TMZ has learned.

We obtained Cleto's death certificate and it lists cardiogenic shock as the immediate cause of death ... with vasodilatory shock, disseminated intravascular coagulation and alcoholic cirrhosis of the liver as the underlying causes.

The document also says other conditions that contributed to Cleto's death include sepsis, graft versus host disease, immunosuppressed, chronic kidney disease and pneumonia.

Cardiogenic shock is a life-threatening condition that happens when the heart suddenly can't pump enough blood to meet the body's needs ... according to the Mayo Clinic.

The doc says Cleto was cremated and the certificate makes note that he was an entertainer who played music for 40 years.

Escobedo had been noticeably absent from "Jimmy Kimmel Live!" for months after falling ill -- before Jimmy confirmed his passing in an emotional Instagram tribute.

Cleto and Jimmy go way back -- they grew up together in Las Vegas, and when Kimmel landed his late-night gig in 2003, he fought hard to make Cleto the leader of Cleto and the Cletones, saying he didn't have better chemistry with anyone else.

Cleto was 59.