1998 International Electrical Issue

I have a 1998 9400 INTL with a n14 Cummins and a 10 speed manual. For the last couple of months my radio will randomly shut off and the CB speaker will crackle. I have looked at the power in wires and didn’t find anything out of the ordinary. Recently running nights with the lights on i have noticed that the dash lights will flicker when the radio shuts off or the cb crackles, and when starting the truck it acts like its not getting enough power or that the starter is going out. The only place that all 3 of these things would be tied into together would be the ignition switch. I have replaced the starter and the starter solenoid on the fire about a year ago. Is this a symptom that the ignition switch is going out? Thank you in advance

 

I’ve heard that international hasn’t been known for their electrical reliability while eating in the driver pits. So that must be true then? I’ll clean up the ground I can find and add another when I get back home. Thank you!

 

Update

I have figured out that the cause for the starting issue was corroded battery terminals I got those cleaned up and the truck starts fine. The issue that I still haven’t figured out is that the radio will randomly shut off and the CB radio will randomly crackle. I’ve noticed my volt meter Fluctuates it never reads any less than 13.9 and will read as high as mid 16 depending on how heavy the pull. It jumps around as you accelerate, but once you’re on level ground or coasting, it will settle back at 13.9 V I cleaned the main ground at the starter and at the frame and cleaned all the connections at the alternator and it’s still continues to do this. I’m wondering is this an issue that I should continue to pursue find a solution or just accept as is.