gbalthrop , thanks for the suggestions, please see my replies below.
Suggestions:
1) Use ISTA or INPA to view "Freeze Frame Data"/ Fault Details for any Fault Code that has "Voltage" FF Data. We're looking for any "Over-voltage" or system Voltage > 16.0V. That will "Scramble" bus communications between Modules. It often causes Wiper "Self-Activation". Restart usually restores proper function (momentarily).
Reply: I have grabbed multiple logs using MHD and the battery voltage always stays between 13.7 and 14.41. I have logs that are a couple of minutes long and there is never a spike. Is this sufficient to rule out the alternator?
2) You can use "Hidden Menu 9.00" to view System Voltage on the instrument cluster, or use Scan tool to display KL30 Battery Voltage or KL87 Main Relay voltage, while you drive, or while engine runs.
https://www.carsaddiction.com/articl...er-hidden-menu
3) Voltage Regulator brush failure/wear on rear of Alternator is most likely cause of Over-voltage.
4) There are other possible causes, particularly if issue began after shop connection to OBD II Socket. You can use ISTA to view wiring (SSP document) of "OBD" II Socket (just search OBD with filter for SSP only. Then examine/test OBD Socket for any obvious damage, particularly to the D-CAN sockets/wiring.
Reply: at the obd port, i found the CAN high and low pins and I get 60 ohms when I place a probe in each location at the same time. I believe that’s normal.
Everything points to a Bus Fault. Whether caused by Overvoltage, OBD II Socket damage, or other Bus wiring/connector fault is the question. I'm NOT an expert on Bus issues, or HOW to diagnose them. I would suggest seeing what ISTA says about Bus Diagnosis, & seeing if ISTA "Test Plan" can help diagnose any of those fault codes.
Reply: I believe it’s a wiring issue but not sure. I am hoping with help from the forum I can figure it out. It’s just weird it popped up out of the blue. My car has around 65k miles on it, is in socal, and doesn’t see rain.
I’m also unclear on the best way to test the wires. Do I get something like this?
https://a.co/d/6DEEAlJ