Holy AC Ripple, Batman!

This stemmed from my attempts to bench test the ABS module from an '04 Silverado 2500HD. Power, ground, Class 2, still not communicating. Triple check all my connections, check I'm in the right pins, still nothing. Green light on the Triton OBD cable is lit. Triton indicates it's charging. This module communicated on the vehicle... What am I doing wrong?

I start checking powers and grounds at the module, just like I would on a vehicle. Checking one of the two power feeds, and what do I see?



14V of ripple! :woohoo: This is easily the highest amount I've ever seen in a DC power source. No wonder this module won't talk!

So, where's this dirty power coming from? That'd be my grandfathers Sears trickle charger from 19-who-knows-when:



I figured, hey, it says 12V on the case, right? :blush: To be honest, I went for this charger because I left my jump pack at work. In fairness to grandpa, all of the cars he was working on didn't give much of a hoot about AC ripple.

Eventually, I did get the module to talk by borrowing one of my M12 batteries: