having trouble starting my Peterbilt for a few days need help!! Thank yiu

If the batteries are weak and your trying to jump it.... it will take awhile. Been there done that. If the starter is lagging when it’s normal.... time to replace the starter. Been there done that.

 

I'd check all your positive and negative connections as well. A rotten cable or poor connection will cause slow cranking speed too.

 

You have bad cells in one or more batteries. My truck did same exact thing, voltage never dropped though. 2 out of 3 batteries was bad. Had to jump it off maybe 4 wkends in a row, thought i had a parasitic drain somewhere that i couldnt find. The last time i tried to jump it off, smoke boiled off the hot post and dang near melted the post in half lol. Took batteries to have em checked and sure enough. Replaced all 3, no more problems.

 

It would drag alot worse the colder it was as well. Warmer mornings, it wasnt half as bad.

 

If you haven’t got it running yet, run a couple tests. I ran into something like this on an old farm tractor, so I’m modifying from that. It’s start with what I know you have on hand. Take your jumper cables and run them from the large power and ground posts on your starter directly to the batteries, if it turns over better disconnect power and crank it again, repeat with the ground also. This will check if your cables they could be burnt or have a bad/loose crimp. You can test the ground strap to the frame also like this
Next if you have a volt meter. Crank the engine to blow off the surface charge, disconnect all your batteries and test their voltage. If one is more than 0.5 volts lower, or below 11 volts the battery is probably the problem.

 

Good deal

 

Volts don't crank your engine. You need cranking amps. Bought a battery analyzer for about $30.00. Will tell you your cranking amps. I had one bad battery. Check all your connections. Cold damp weather has an effect.

 

If your batteries test good my money is on the starter. We’ve got 7 379s and identical simptums happened to a truck last winter and a different truck this winter. Crank over a few times and no start. Always when it was less than 15. Put a new starter and they were good as new.

Good luck jumping it. I tried jumping the trucks in those scinereos and I had good quality 0 gauge cables for an hour+ with no luck. Try plugging the truck in for a few hours. It will help it start if you get the block temp up