2020 Cascadia AC and voltage issues

Check your grounds, there are a lot of them. We pay with a credit card so if we get some mechanic like this, we dispute the charges for labor based on the issue that he is not diagnosing the issue.

 

Your voltage should be 13.2-13.6 ish when driving.

You're losing accys because of low voltage.

Loves guys.... well, you know

I'd be checking the alternator wiring and voltage 1st

 

It should have been charging 13.5 after the battery change.

You have a charging issue

 

YEP go to the dealer and get them to fix it. It sounds like a grounding problem, it takes both a ground through the chassis and engine to make the alternator work right. It could be a corroded end or a bad cable, for that matter that will cause the alternator's regulator to just see there is no need for voltage above what you are getting.

SO take it to the dealer.

 

Do you know if your truck has the aluminum battery cables. There was a recall you can google it or call Freightliner and see if your truck was already fix or affected. I had company truck doing funny electrical stuff they did not want fix it right away or look at it. Then going down the road one day the engine just cut off and they had to call tow truck. The repair was doing the recalled aluminum battery cables.

 

**** I forgot all about that, so here is the link ...

https://static.nhtsa.gov/odi/rcl/2021/RCMN-21V481-7216.pdf

 

Seems like if your batteries are dropping while you are sitting with everything off, then you have a short to ground. You can put a multimeter on batteries (main bus for fuses/ circuit breakers) and see if there is any current draw with everything turned off, then if there is start pulling fuses or flipping breakers one by one until you find the circuit responsible, then check that wiring. Disclaimer: This advice is worth what you paid for it because I don't really know crapola about truck repair.