I'm having a starting issue with my 04.5 for the second winter in a row. When it's warm the truck starts just fine but when the temperature drops into the 40's it's slow to turn over and start. Plugging in the engine heater helps, but if the temperature drops down into the 30's it still turns over pretty slowly. All of the injectors were replaced about 40,000 miles ago; one of the injector solenoids did fail a couple of months ago. It was replaced by a reputable diesel repair shop and the shop said the rest of them passed a diagnostics test. Everything worked great until the temperatures started dropping a couple weeks ago. I'm going to independently charge up each of the batteries and perform a load test on each of them separately. The Interstate batteries are less than three years old but you never know if one could develop a bad cell. Assuming the batteries pass the load tests, I'm guessing the starter could be the culprit, but I don't know how to troubleshoot that issue. Thanks for any replies.

 

Here's the easy way to test it. First, don't charge your batteries. leave the truck outside at night. In the morning, load test the batteries individually. this will tell you if you have a bad one. I think that you do have a weak one and the cold will definitely make it show. If not then clean all connections especially the ground cables going to the body and frame. Also get a pair of jumper cables, Put them from one battery to another to eliminate the positive cable that runs between them. If then you still have a starting problem it will more than likely be the starter. But put the load tester on the left side battery and check to see what the voltage is while cranking the truck over.