EE WAS DISPATCHED IN MAINTENANCE SERVICE TRUCK U-932 TO WORK ON A WHEEL LEAK ON END DUMP UNIT 302. AS HE WAS GETTING OUT OF THE SERVICE TRUCK, HIS FOOT SLIPPED OFF OF THE STEP OF THE SERVICE T RUCK, AND HE GRABBED THE STEERING WHEEL OF THE SERVICE TRUCK TO KEEP HIMSELF FROM FALLING. HIS LOWER BACK MUSCLES WERE STRAINED IN THE PROCESS. HE NEVER FELL TO GROUND. HISTORY OF BACK PROBLE