[2000CAYukon]

I bought my 90 GMC K1500 Sierra 17 years ago this month. I am having my own set of electrical issues (intermitten rough idle when hot); otherwise, it has been a great truck.

To me, this sounds like a bad battery cable or ground. You need to clean both ends of both battery cables. Even if the cable looks good, it could be corroded inside. On my 90, the battery ground is connected to an intake manifold bolt (passenger side). Then there are 2 other grounds which are for the ecm and o2 sensor. One is at the tstat housing and the other is at an intake manifold both (drivers side). Make sure these are good and clean.

Also, on the passenger side, there is a grounding strap from the frame to the back of the head and from the back of the head to the firewall. Make sure these are connected and clean.

If all of these looks good, then I would look at the ground for the headlights.

Good luck and post back any findings.

//2000CAYukon