Electrical Issues: COR clicking, radio cuts out, truck sputters, headlights cut out

So it started about 1 month ago. I was driving to work all was well and then I start to hear this clicking sound coming from the dash, the radio cut out, and then I started chugging and stalled... The truck wouldn't even crank over. So I ended up having to call a tow truck to come and get me.... It's a sad sight when a Taco is on the back of a flat bed.

Anyways, I left the truck for about a week before I had time to look at it. When I came back to it, it started right up like nothing had happened. It didn't seem to have any symptoms for about a week, but then it did the same thing again, but it didn't stall this time.

I finally figured out that it was the Circuit Opening Relay that is clicking, so I swapped the EFI with another relay that's the same to see if that was the issue, it wasn't. for the past month, the truck has been drive-able, but barely. It has the same symptoms, and the truck really stutters like it wants to stall, but it hasn't yet.

I just ordered a new COR that will be showing up today, but I'm thinking that, that's not the issue...

Any ideas?? This is going on too long! I want my reliable taco back.


We followed all of the grounds to see if anything was wrong and couldn't find anything. I purchased a new COR relay... no changes. But here's the weird thing. When all of the symptoms start happening again we plug in our scan tool and all of the symptoms stop completely. If you unplug the tool, it all starts up again... We've tested it multiple times by doing that and every time, the scan tool stops the problem until we unplug it and then it starts back up again.

Any ideas what that could be???
Maybe the ECU?