Need help tracking a bad ground wire
Thread Starter
Advanced
Joined: Apr 2007
Posts: 78
Likes: 0
Need help tracking a bad ground wire
I have a 87' c4 with a bad ground somewhere. I need help tracking down some wires. On the plug to my alternator, the brown wire is reading hot when tested. Do anyone know where this wire start from. The car will barely run by itself, and when trying to throttle it, the car will shut down and cut off. But when I unplug the alternator the car runs fine. I know its a bad ground because when I unhook the ground cable to the battery the car shuts off. I also found out, that both sides of my fuel injectors plugs are also reading hot. So now i'm try trying to locate the bad wire, but the haynes manual I have, don't clearly tell me where each wire goes. I'm also looking for help with the wiring diagram for the fuel pump relay. I noticed something fun with the wires going to the relay when using the ohm meter. When I touch one of the hot wires with the ground side of the battery i had resistance. Thank you for any help you can share with this problem.
purplehayes
purplehayes
Race Director
Joined: Dec 2006
Posts: 10,383
Likes: 4
Alt/Gen warning light in the dash.
So now i'm try trying to locate the bad wire, but the haynes manual I have, don't clearly tell me where each wire goes. I'm also looking for help with the wiring diagram for the fuel pump relay. I noticed something fun with the wires going to the relay when using the ohm meter. When I touch one of the hot wires with the ground side of the battery i had resistance.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
If you have a wobbly table at home, use the Haynes under the short leg and then buy an 87 field service manual, including the electrical diagnosis service manual supplement. Then you will get some detailed information on how each system works, parts locations, wire colors, and diagnosis procedures for typical problems.
Your alternator has a shorted diode and probably gets too hot to touch if left plugged in long enough. Have it tested at an auto parts store to confirm this.
You got good info from 94z07fx3. If you want more help, then provide a better describe your symptoms.
Welcome to the Corvette Forum.
Your alternator has a shorted diode and probably gets too hot to touch if left plugged in long enough. Have it tested at an auto parts store to confirm this.
You got good info from 94z07fx3. If you want more help, then provide a better describe your symptoms.
Welcome to the Corvette Forum.
Safety Car
Joined: Oct 2007
Posts: 3,816
Likes: 0
From: :45 minutes from everywhere / E-I-E-I-O
Can't find a ground?
Reminds me of a dog I saw once, who became the ground for an electric fence wire. He sniffed and raised his leg.
Ever hear those summertime bug lamps when a bug gets zapped? Zzzzzzzt. I heard that sound, then I heard a sensory input sound from the dog that meant bad things were happenin'. Fast.
Thread Starter
Advanced
Joined: Apr 2007
Posts: 78
Likes: 0
I've tested the volts on the alternator, with the voltage meter. While the car was running, the voltage reading was all cross the board. Never giving a stable reading, the range was from 11.2 to 16.0. The reading would only become stable at 13.4 when the three prom plug to the alternator was disconnected. This is also when the car runs perfectly while the plug is disconnected. The voltage gauge inside the car would only read 11.7 or less during the entire test. It appears to me that car is not charging at all. The only thing is I have replaced the alternator already, but I'm still getting the same problem.
purplehayes
purplehayes
Safety Car
Joined: Oct 2007
Posts: 3,816
Likes: 0
From: :45 minutes from everywhere / E-I-E-I-O
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
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
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
Burning Brakes
Joined: Apr 2005
Posts: 1,110
Likes: 0
From: JUPITER FLORIDA
Make sure your alt. is on its brackets tight. That bottom bolt on that alt. can break if the bracket from the alt to the exhaust mainifold isnt on. Mine broke and the reading was all over the place from the alt jiggling around. Just take a quick peek to be sure.
