Need help. I have a 07 lmm duramax that the starter enguages and starts to rotate engine, then loses power.If you hold the ignition in the start position it will keep cycling this process over and over.But will not stay in long enough for it to start. This problem only happens in the winter at temperatures below 35 degrees. Any other time, no problem. Good batteries, clean cables, good starter

 

Check the starter fuse under the hood if when you change it and it blows again wiring under your passenger engine has a peeled wire and is shorting it out can try there

 

have you tried checking the voltage while cranking over? if i am not mistaken, the lower limit is something like 9 volts. if it gets near or below this then you will have issues like you describe. i would also check all of the grounds and connections running from the battery to the starter, etc. to make sure they are clean and tight.

also, if the voltage looks good at the batteries while cranking, it would be a good idea to check the voltage that the starter to see what it is there too. i would think it would not be more then about one volt less then the reading at the batteries. if it is more then you have a bad connection or some corrosion on one or more wires

 

Check the electrolyte in your batteries, and test them. I have one bad battery l, and if mine sits for more than a couple days it will drain the one good battery, and do what your describing.