A new issue just happened all at once on this 95' Z71. My Son drove it to school, and when he placed it in park before he shut it off the idle started surging up and down. The next thing he noticed was the gauges were acting funny, jumping around, especially when putting the turn signal, flashers, or headlights on. Also noticed that when he applied the brakes after this...some power was going to the headlights, and was partially illuminating them. He said, the only thing different that morning was he had to slam on the brakes to avoid hitting somebody. Any ideas out there on this one? After school he tried to drive it home, but was afraid to because the temp gauge was showing it was running hot.... All was good before this??? Frustrated

 

It act's like an electrical connection. Look at the connector on the firewall going to the cab, might be loose.

 

with kevin on this but i would think it would be more ground related. the ground will cause all sorts of running issues because the ecm isnt getting proper signals from the sensors due to the interference of the engine. the lights will also back feed into each other due to poor connection. since its both the ecm and lights acting up i would be looking at a main ground vs one of the smaller ones.

 

I vote ground as well. Take off battery cables & clean well and check negative cable to motor. Make sure battery is well secured as you say this happened after a hard stop.
Please report findings

 

thanks :-)...going to look at that my next day off !

 

Turns out, when we did the engine swap a few weeks ago we left the ground straps off on the passenger frame to the body, and block. Put those on today, and the issue seems to be solved ! I'm surprised it went a week and a half before it started to act up ? But...thanks all for the replies :-)

 

congratulations on fixing the issue and checking back in