voltmeter and my temperature gauges are not working

1984 CHEVROLET TRUCK
1 MILES • 7.4L • V8 • 2WD • AUTOMATIC
Avatar
TWEBB101
  • MEMBER
  • 183 POSTS
Hello, my voltmeter and my temperature gauges don't work; needle looks to be broken as they are not pointing to any numbers. Is there a "common" reason for this? Or am I looking at new gauges? Maybe a new printed circuit board?
Nov 5, 2021 at 2:19 PM
Advertisement
Avatar
KASEKENNY
  • Experienced Mechanic
  • 18,907 POSTS
The only thing that these have in common is the cluster so what I would do is remove the cluster and check the connections at the back and make sure there are no issues.

Then check the voltage at the meter as shown in the attached info below.

Here are a couple guides that will help with testing this voltage:

https://www.2carpros.com/articles/how-to-check-wiring

https://www.2carpros.com/articles/how-to-use-a-voltmeter

Please let us know what you find and what questions you have. Thanks
Nov 6, 2021 at 8:46 AM
Avatar
TWEBB101
  • MEMBER
  • 183 POSTS
Great, thanks. Can these come out without removing the dash pad, or no?
Nov 6, 2021 at 9:54 AM
Avatar
KASEKENNY
  • Experienced Mechanic
  • 18,907 POSTS
It has been a while but no. I think you can access all the screws around the cluster without removing it. The instructions I attached above do not say to remove it either so you should be able to get to them all. Take a look at the second page I attached on my last response and let me know if you need more info or how you make out.

Thanks
Nov 6, 2021 at 11:16 PM
Avatar
TWEBB101
  • MEMBER
  • 183 POSTS
Lots of work done since last post, but I have replaced the voltmeter and oil pressure gauges (other gauges are backordered). I also replaced the circuit board, retaining clips, and lights. After starting the truck today, the oil pressure gauge was maxed at 60 PSI. Is that normal, or is something else faulty now?
Dec 10, 2021 at 9:50 AM
Avatar
KASEKENNY
  • Experienced Mechanic
  • 18,907 POSTS
It is possible that the gauge is accurate but if it is maxed out then the likely cause is the wiring is grounded and not running through the resistor in the gauge.

Basically, the way it works is there are two magnets that pull the needle to where it needs to be. So, one side is grounded, and the other side runs through a resistor which causes the needle to move through its sweep based on the sensor input.

So, if it is pegged in one direction, that tell me that the other sides magnet is not working which means that wire is grounded prior to the magnet.

So, we need to check for a short to ground or just run a new wire from the sensor to the gauge.
Dec 11, 2021 at 4:06 AM
Avatar
TWEBB101
  • MEMBER
  • 183 POSTS
As a follow up to this: the oil pressure is running just under the 60 psi mark, so I think it's working ok..? However, the voltmeter gauge is now having issues: it was working great, and then while driving it, the needle just jumped to 3 o'clock. When I turn the truck off, the needle goes back to 0; turn the key on...back to 3. It's getting power, but no signal. I've checked all the wires, but no luck. Is there a fuse, or something else going on?
Feb 20, 2022 at 4:47 AM
Avatar
KASEKENNY
  • Experienced Mechanic
  • 18,907 POSTS
Thanks for coming back to update us but we are going to have to get a new post started as we need to keep each post to the same issue. Basically, others that are having an oil pressure gauge issue will want to see how you fix yours, but they won't find it under this post.

https://www.2carpros.com/questions/new

Sorry for any inconvenience but when you solve an issue it not only helps you but all others that view this in the future, so we want them to find it.

Thanks
Feb 20, 2022 at 11:22 AM
Join 2CarPros for free, one of the most advanced car repair communities on the internet. From first-time drivers to seasoned mechanics, everyone is welcome to reply, share details, and get better answers. You can add a temporary image or video first; uploads are limited to 20 MB.
Ask a Free Question
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.