Hey everyone,

I have a 1990 K1500 with a 5.7, probably over the past year I have been having electrical issues with it. I will try to explain it the best I can without making it confusing.

When the head lights and brake lights are on the voltage meter will drop to about 11 volts. When I hit the brakes it will drop even further. Any other electrical load will also cause it to drop. Also any electrical load will make the oil pressure and temperature gauges drop too causing the check engine light to come on. It seems the longer my trip is the worse it gets. During the day time the voltage meter will stay just below 14 volts. I recently had the alternator tested and it came back as a good test putting out 14 volts and the battery is also a brand new red top. The only aftermarket electrical components are a radio and four new speakers, nothing big just replacements.

Any help with this issue will be greatly appreciated. Thanks for the help.
Chevrolet
K1500 1990
4x4
5.7 350
Regular cab, long bed