Volt gauge

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

77 K20

Full Access Member
Joined
Nov 9, 2012
Posts
3,075
Reaction score
3,044
Location
Montana
First Name
Mike
Truck Year
1977
Truck Model
K20 5" lift
Engine Size
HT383 fuel injected
My dad and I did a 6 hour road trip in his 1979 GMC K15 yesterday and I got to drive his truck. I had only made it about 50 yards from his house and was checking out his gauges and saw the volt gauge was only reading about 12 volts. Stopped and turned around and went back to the house. Had him dig out his volt meter.

He swapped out his alternator he said probably 8 years ago for a 1 wire alternator (instead of the factory 2 wire). But said the volt gauge was working. I verified at the battery it was getting 14.0 volts. Went on the trip. On the 3 hour drive there it would hop up to 13.4 volts or so for a few seconds, then drop back to 12 volts where it spent most of the time. On the drive back it was about 50/50 whether it was reading 13+ or just 12 volts.

Any ideas? Where does the factory volt gauge tie into the trucks electrical system? Fuse box? Wanted to measure the voltage there... or is the gauge itself going out? But why drop to 12 volts? Figured if the gauge was going out maybe it would read 0 volts...
 

bucket

Super Moderator
Staff member
Super Moderator
Joined
Aug 3, 2010
Posts
28,966
Reaction score
23,492
Location
Usually not in Ohio
First Name
Andy
Truck Year
'77, '78, '79, '84, '88
Truck Model
K5 thru K30
Engine Size
350-454
It just gets it's power from the printed circuit on the back of the cluster, the same power supply that the other gauges get. Very likely just an old inaccurate gauge.
 

Latest posts

Forum statistics

Threads
41,859
Posts
903,669
Members
33,372
Latest member
83elcowes
Top