Rep Power: 0

Fuses checked and all working properly. Horn works. SRS light is on. This is a new issue (cruise used to work perfectly for 2+yrs in spite of SRS light)

Click the cruise button and the light comes on. During the day (headlights turned off) it sets/maintains, decel, accel, all works perfect.

However, whenever the headlights are on, the light for the cruise button comes on but it won't set/maintain. I have tried testing if it's an electrical drain issue via turning on interior lights, cranking the sterio, etc, nothing else seems to impact the cruise. I can't for the life of me figure out why / how this could develop and yet be so specific in how/when it happens. (Edit: I've tested this multiple times, setting and then turning on the headlights as well, it drops right out of cruise control instantly)

This started happening, about 2-3 months later I had other electrical issues (lights/radio turned off when at a stop/idle) and I suspected the alternator, which was confirmed and replaced. All other electrical oddities stopped, but the cruise control issue remained exactly as it was before (works with headlights off, won't work with headlights on). Battery was replaced 1yr+ before any of these issues came up. No other work was performed on the vehicle around the timeframe of the cruise issues starting (no new lights etc.)

I've searched everywhere for anything like this but failed to find symptoms that are similar. Any ideas are welcome and appreciated. I'll admit I'm fairly novice at fixing things but I can find and follow instructions if someone has any ideas on what might point me in the right direction.

 
Rep Power: 222

I would guess the clockspring (srs cable reel) is bad. Behind the airbag on the wheel.
Pull one from a junkyard, try to find a car a similar to yours as you can. Same year, engine, trans, and cruise.

 
Rep Power: 0

Presumably that'd be for the SRS light.

Are you thinking that has impacted the cruise system? Or is it necessary to fix the SRS system in order to properly diagnose the cruise?

 
Rep Power: 222

The wires are part of the same harness for the cruise buttons, headlight switch, and the airbag.
SRS light might be something else though