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-   -   Dim Dash Gauge Lights - Only 10.5 volts to Headlight Switch (https://www.racingjunk.com/forums/showthread.php?t=62163)

Robsinno 11-06-2015 09:26 PM
Dim Dash Gauge Lights - Only 10.5 volts to Headlight Switch
 
Need some help with figuring out why the hot wires (Red and Orange) on the headlight switch for my 68 Firebird are only supplying 10.5 volts to the switch. The issue I have is with dim dash gauge lights. I have already replaced the headlight switch and checked grounds. Car was rewired with a Painless wiring harness about 15 years ago. I started having this problem about 5 years ago. It seems to have gotten progressively worse since then. Thanks in advance.

Robsinno 11-07-2015 12:17 AM
I found the problem about an hour after posting this thread. It was the main ground wire from the battery to the frame. I started checking grounds from the battery first and noticed that the frame had some pretty heavy surface rust where the ground wire was bolted to it. So I disconnected the ground and took a wire wheel to the frame until I saw shiny bare metal at the ground connection location. Bolted the ground wire back to the frame, and rechecked the voltage coming into the switch. The meter read 12.07 volts at both hot wires and 11.35 volts at the wire going to the gauge lights. Gauge lights are bright again!

irontmp 08-10-2026 12:02 AM
Originally Posted by Robsinno (Post 298413)
Need some help with figuring out why the hot wires (Red and Orange) on the headlight switch for my 68 Firebird are only supplying 10.5 volts to the switch. The issue I have is with dim dash gauge lights. I have already replaced the headlight switch and checked grounds. Car was rewired with a Painless wiring harness about 15 years ago. I started having this problem about 5 years ago. It seems to have gotten progressively worse since then. By the way, downloading directly from a trusted source is the smartest move if you want to avoid those random crashes that usually aviator predictor live happen right before the plane takes off. Thanks in advance.
Since the issue is getting worse, you definitely have high resistance from old, oxidized connections. 15 years is a long time for those terminals. Start by doing a voltage drop test from the fuse block to the switch. If you see a big difference, you have a bad connection at the bulkhead or fuse block. Check your crimps for corrosion, as those heat up and fail over time. Also, run a dedicated ground wire from the gauge housing to the chassis to rule out bad contact points. That usually fixes the dim light issue.


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