Negative Voltage on a '73
Thread Starter
Racer
Joined: Dec 2003
Posts: 399
Likes: 0
From: Haslet,Texas
Negative Voltage on a '73
Is it normal for the '73 to have negative voltage readings? Currently, my positive battery lead is connected to ground, and my negative lead goes to the starter. Is this how it should be?
Le Mans Master
Joined: Jun 2002
Posts: 8,339
Likes: 24
From: I can walk to MA
Re: Negative Voltage on a '73 (73'Vette)
... and there's no smoke coming from the alternator ?
Holy crap ... NO ... Negative to ground and positive to the starter.
Are you sure ? double - triple - check.
The negative lead should exit the body and bolt directly to the frame.
The positive runs up the tranny tunnel to the starter.
I would think that some electrical systems would be OK with reversed
polarity, but not the charging system (alternator) - for sure.
:confused: :confused:
[Modified by NHvette, 1:21 PM 2/10/2004]
Holy crap ... NO ... Negative to ground and positive to the starter.
Are you sure ? double - triple - check.
The negative lead should exit the body and bolt directly to the frame.
The positive runs up the tranny tunnel to the starter.
I would think that some electrical systems would be OK with reversed
polarity, but not the charging system (alternator) - for sure.
:confused: :confused:
[Modified by NHvette, 1:21 PM 2/10/2004]
Thread Starter
Racer
Joined: Dec 2003
Posts: 399
Likes: 0
From: Haslet,Texas
Re: Negative Voltage on a '73 (NHvette)
The alternator isn't hooked up yet. Everything else runs fine with the negative voltage though. All the lights work, the car starts, etc. I wonder why the heck the prior owner would have hooked it up like this??? I hate messing with the electrical system, and this has me worried. I'll eventually need to get the alternator charging, and this makes me nervous.
Le Mans Master
Joined: Jun 2002
Posts: 8,339
Likes: 24
From: I can walk to MA
Re: Negative Voltage on a '73 (73'Vette)
Perhaps they didn't even look when connecting the battery.
Why don't you simply disconnect the two cables at the battery and switch
them to the correct terminals ? side terminals - right ?
Why don't you simply disconnect the two cables at the battery and switch
them to the correct terminals ? side terminals - right ?
Thread Starter
Racer
Joined: Dec 2003
Posts: 399
Likes: 0
From: Haslet,Texas
Re: Negative Voltage on a '73 (NHvette)
Yes, it is side terminals. The thing that has me confused is that the colors are even swapped. The red connection is currently connected to positive as it should be, and the black connections is connected to negative. But as I mentioned before, the other end of the red is grounded, and the other end of the black end goes to the starter.
Safety Car
Joined: Aug 2001
Posts: 3,685
Likes: 202
From: Waterford Mi
Re: Negative Voltage on a '73 (73'Vette)
Things like light bulbs don't care which way they are hooked up. If you are hooked up backwards the starter could even run backwards so the engine couldn't start. Was it running when you started working on it? My dad hooked up a battery charger on his lawn tractor backwards and completely burnt up all the wiring. Sounds strange to me.
Thread Starter
Racer
Joined: Dec 2003
Posts: 399
Likes: 0
From: Haslet,Texas
Re: Negative Voltage on a '73 (redwingvette)
Nope, it wasn't running when I got it. I had it brought to my garage via a flatbed. I'd like to be absolutely sure it is hooked up backwards before I reverse the leads. From the sound of it so far, it is indeed wired incorrectly. Any other opinions?
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Le Mans Master
Joined: Jun 2002
Posts: 8,339
Likes: 24
From: I can walk to MA
Re: Negative Voltage on a '73 (73'Vette)
Yes, it is side terminals. The thing that has me confused is that the colors are even swapped. The red connection is currently connected to positive as it should be, and the black connections is connected to negative. But as I mentioned before, the other end of the red is grounded, and the other end of the black end goes to the starter.
Have you done this ?
Or - crawl under car and verify that the 'red' cable is bolted to the frame.
The negative terminal of the battery should connect to the frame. Period,
regardless of color.
I recall the starter battery cable to have a black jacket, but I cannot confirm
this, as my body is at home, outside under a tarp. I'll try to take a look tonight.
Thread Starter
Racer
Joined: Dec 2003
Posts: 399
Likes: 0
From: Haslet,Texas
Re: Negative Voltage on a '73 (NHvette)
Yup, I'm absolutely sure that the positive lead is going to ground, just below the battery box. I've checked and double checked, since I've never seen this before on a vehicle. I don't think there is any other way that I could get negative voltage readings if it was wired the normal way. All voltages should read positive, correct? I'd appreciate it if you would check your cables for me. :)
Racer
Joined: Jan 2004
Posts: 377
Likes: 1
From: Anchorage Alaska
Re: Negative Voltage on a '73 (73'Vette)
I'm not sure where you are taking your readings, or what you're using, but, Start at the battery terminals to be sure you have the right polarity on your meter, and go from there. As "redwing" said, if it's backwards, i.e., the negative to the starter, the starter would run backwards.
Le Mans Master
Joined: Apr 2001
Posts: 5,000
Likes: 1
From: Minneapolis, Mn USA
Re: Negative Voltage on a '73 (73'Vette)
HOLY CRAP is right.
Your frame should be negative and your + battery terminal to starter should be positive. The voltmeter has polarity and use the negative lead to the frame and the positive lead to your + battery terminal to determine wiring polarity.
Your alternator has diodes that would allow current flow if polarity was reversed, so by not having this installed, your car is probably saved. Your very lucky your car has not self destructed. The battery has enough power to arc weld and create heat that burns up wiring and your car in minutes.
Unhook battery immediately and fix.
Brent...
Your frame should be negative and your + battery terminal to starter should be positive. The voltmeter has polarity and use the negative lead to the frame and the positive lead to your + battery terminal to determine wiring polarity.
Your alternator has diodes that would allow current flow if polarity was reversed, so by not having this installed, your car is probably saved. Your very lucky your car has not self destructed. The battery has enough power to arc weld and create heat that burns up wiring and your car in minutes.
Unhook battery immediately and fix.
Brent...
Melting Slicks
Joined: Aug 2003
Posts: 2,135
Likes: 2
From: Dayton Oh
Re: Negative Voltage on a '73 (73'Vette)
Is it normal for the '73 to have negative voltage readings? Currently, my positive battery lead is connected to ground, and my negative lead goes to the starter. Is this how it should be?
Melting Slicks
Joined: Oct 2002
Posts: 2,865
Likes: 1
From: I may be getting old but I refuse to grow up
Re: Negative Voltage on a '73 (73'Vette)
Another question I can't answer is how in the heck is it starting with the starter turning the wrong way?
Steve :steering: