converted amp gauge to a volt gauge and now pin jumps

[james133]

when I the turn car off the pin jumps on the volt gauge not sure why also when connected the the old amp gauge wires I connected them together with nut and bolt screw then used electrical tap a lot of electrical tap to seal it off should I have used something different then tap something more heat resistant

 

[eric383]

I prefer to solder the wires together but if the bolt and nut is tight it should work. Electrical tape is fine as long as everything metallic is covered. I'm not sure what would cause the needle to jump but if everything is operating correctly I wouldn't be concerned. If you do pull the dash out in the future I would solder the wires together. Good luck.

 

[nm9stheham]

The bolt and nut is fine; make sure there is a star lock washer on each side and it is torqued as tightly as you can. Use some electrical contact grease or No-Ox on the joint; that will protect it from future corrosion. Also, inspect inside the lugs on the ends of these 2 wires and make sure that the copper wire going into the lugs is clean, not green and corroded. If corroded the least little bit, they need to be cut out and rejoined.

Tape is Ok for temp stuff, but cheaper tape will tend to dry out and unwrap over the years. This point is too critical and can cause a fire if the tape comes off and the wire shorts, so I would use heat shrink tubing instead.

Sometimes solder joints can crack from normal car vibrations so if you do this, make sure the both wires are well supported going into the soldered joint.

As for the needle jumping at turn-off, where did you connect the voltmeter to? Please give an exact description of where it is connected. And what voltage does the voltmeter indicate when the car is running at slow idle, and also at fast idle or curise? It sounds like you connected it into a spot a bit far from the battery and that naturally has lower voltage when the car is on. Or you could have some excessive voltage drops somewhere that need investigating.