electrical gremlin

How old are your batteries? They are probably junk.

Separate your batteries and test them with a load tester. You should also clean all posts and terminal connections at the batteries as well. If the batteries are older than 3 years I wouldnt even bother testing them, just replace.

 

Volvos are known for their electrical problems.

 

I cant say Volvo electrical system is bad. But not the best.

The only problem of Volvo is wiring.

Trucks like Actros MP2-3, MAN TGA are more complicated. But they got better wires. Cascadia electrical system is like simplified Actros, so hard to understand how does it work, like Volvo Version-2.

All new Renault and Mack trucks got Volvo style electrical system too.

Scania is not simple thing too!!!!

DAF, KW and Pete have simpler systems.

As example of complicated electrical system combined with weak wiring are Iveco Stralis and MAN TGA.

BTW, guys, US Volvo wires are thiker, becouse EU volvos got 24 V systems with thin wires, that fail on bad roads. So more issues with FH!

 

inspect all connectors in battery box and chassis to cab power supply wiring.

 

Hate to say this, but you should always replace ALL batteries at the same time. 1 bad battery will screw with the rest of them.

Not trying to beat a dead horse here, but... I barely got two years out of my batteries. I have an APU and our APU's treat the batteries like deep cycle batteries, not a good way to treat our trucks starting batteries. Severely limits their life span.

Any update, kinda curious to see what the problem was?