Hi Scotty

I desperately need some help.

My car will not run or start with the headlight switch in the on position.

It runs and drives just fine otherwise.

This first happened a few months ago, briefly, then it went away and I hadn't had an issue again until yesterday. Birth times the first sign was that a few days lights would come on or flash and my speedometer would act up and drop down for no apparent reason, usually at the same time the dash lights would flash. 

Then the car might stall or hesitate briefly.

Then the car wouldn't run or start at all with the lights in the on switch or if I turn on the left blinker. The right blinker works fine. And now the head lights wont come on at all. It still cranks over just fine.

It's been somewhat intermittent the past two days. Yesterday there were times when everything worked fine, then later if I turned on the lights on hit the blinker it would stall. There was a couple of times where it started to stall but revved back up to idle. 

Today I was able to start it up, turned on the lights and it sat there and idled fine for a bit. I pulled out to drive and then it stalled and now it consistently won't run with the lights "on". Although the headlights down actually turn on. Yellows turn on fine. Left blinker flashes rapidly and weakly and several. Without the light switch in it runs and drives fine.

I had the battery tested yesterday and it checked out fine as expected as it's only two years old. 

I checked the mass air flow sensor and it looks fine.

There are only two things I can think of that could be the root of the issue.

First, I was in a minor accident earlier this year and the left headlight assembly was replaced in the repair work. That's also the left side that seems to be somehow connected to the issue. Could something here be shorting and/or drawing too much voltage?

Second, there's something wrong with the ECU. 

Any advice to get me pointed in the right direction of where to look or how to test things would be greatly appreciated.

Regards

Geoff