Ok electrical gurus, here’s a weird one for you. Finally got our car together and started. It’s a 30 Chevy but irrelevant to the issue. Aftermarket Dolphin gauges and light switch. Here’s the issue: When either the key is ON or the car is running, all dash gauges work ok but, when I pull the light switch on, the Volt gauge goes to 0v and the Oil Pressure gauge pegs at full. This is with the switch in the Park or Headlight position. Also, the gauge light do not come on. This is regardless of key or switch position. I had the dash panel out when building the car (PO had installed the panel/gauges). Everything was working properly prior to taking it out. I drew a diagram at the time and it went back in the same way it came out. I know the ultimate answer is going to be start cutting zip ties but so far everything looks right. The only thing that has changed is the PO had the Alt power lead going to the Ign switch Batt terminal and a lead from there to the battery. I corrected that with the power lead straight to the battery and a separate Hot lead back to the Ign switch. Obviously I cocked something up but it’s a strange problem. Just looking for a commonality between issues before completely cutting everything under the dash loose. My fat ass doesn’t seem to fit as well as it did 30+ years ago. Sent from my iPhone using The H.A.M.B. mobile app
x2....Only will take minutes to add a ground jumper from a known perfect ground like chassis or battery, to know if it is that. Don't assume that the entire dashboard itself, or the body, is grounded correctly at this point. .
As others mentioned the ground is as important as hot. A poor or no ground means anything supplied with power will find a ground somewhere so whacky things happen. Sent from my SM-S320VL using Tapatalk
As mentioned above... check your grounds. sounds like its looking for a ground path through the instrument panel. I have troubleshot some weird electrical gremlins only to find a bad ground leg on a circuit.
Ha. Easier than my last electrical problem. Slam the door .... the horn honked. WTF right ? Good luck !
I’ve gone back through all my grounds but I’ll run a temporary ground to the batt. Sent from my iPhone using The H.A.M.B. mobile app
Like I always told my helper, “ if it doesn’t make any sense, check your grounds “. Probably your problem or a loose connection. Bones
I ground engine to frame , frame to body , engine to body , also I clean the metal first , clean the copper ends, then paint over the connections...you gotta have connections..ha ha ha
There have been some issues with Dolphin gauges in the past. I think I would disconnect the wire for the gauge lights and see if that corrects the problem. No where do I see where you have pulled the gauge light power from. The gauge light power should come from the instrument light power pin on the light switch, and the lights should have their own ground wire. Gene
I appreciate all the suggestions. The grounds are all good. The two gauges in question are on the same side of the cluster. My guess is they are both losing “gauge power” when the lights are pulled on. The dash lights may or may not be related. That’s a secondary issue anyway. I’m thinking that when I fixed the alternator power lead/Ign switch I inadvertently swapped something up. There was some shaky electrical, although everything did work before. I don’t seem to be as bendy as I used to be. Might have something to do with this big pus gut I have. Keeps rolling up under my chin. I don’t recall it doing that in my twenties. Sent from my iPhone using The H.A.M.B. mobile app
Are you using standard bulbs or LED's? New LED's need a resister , they will back feed and will cause a lot of problems. Have seen gauges not work with lights on and will work with them off, seen dash lights blink with the turn signal on, head light go off when the brake lights come on and then back on when brake light goes off because some one put a LED in the right side and a 1157 in the left side rear. Good luck
Nope, just good ol’ fashioned incandescent bulbs. America Sent from my iPhone using The H.A.M.B. mobile app
I had a problem with some So Cal gauges....assumed the "G" post on the gauges was for the ground. It wasn't. Switched ground and keyed 12 volt feed with each other and viola! Problem went away.
Just a quick update. Of course, frickin ground. Never found the break. Just ran a new one. All is well now. Thanks for all your help. Sent from my iPhone using The H.A.M.B. mobile app
Two things I’ve learned playing with cars for 30 years: If it’s an electrical issue, it’s a ground. If it’s not running right, it’s NEVER the carburetor. The times when the above are not true are just the exceptions that prove the rule.