The TOPDON LITE scanner indicated that the the Glow plugs in cylinders #1,3, 5 were bad. I removed
them, tested with an ohm meter and they checked ok. Then I tested them with 12 volts DC and
they would get red hot in only about two seconds. With a TOPDON PRO hope for something new
will come up. So far, the 6.6 L Duramax LLY
makes no effort to start with the starter spinning great.