What's wrong with my rendezvous if my lights shut off and will not start

I'd check the battery. You can still have enough battery power to run the lights, but not the starter. I'd also check the alternator because that may be bad. In my case, the alternator went out and discharged my battery and I was sitting on the side of the road!

Ecu there was a problem simular and it was the problem check engine light was on for weeks then all gauges quit working then it started to hesitate when u give it gas new ecu reprogrammed it and everything is fine