electrical problem won't start
Thread Starter
4th Gear
Joined: Jun 2025
Posts: 4
Likes: 2
electrical problem won't start
1972 Corvette, 350, 4-speed. was running fine then today went to go for a ride and car would not start. not even a click when I turned on the key to start. Checked battery voltage and it was almost 13. Voltage at the starter, relay and alternator 12 plus. if I turn on the interior lights to create a draw the voltage at the starter, relay and alternator drops to zero. Help! Thanks in advance for any help.
Race Director
Joined: Nov 2006
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From: Sunshine Coast, Queensland, Australia
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Cruise-In VIII Veteran
Voltage drops to zero when you just turn on the interior lights? Sounds like a bad connection.
most likely culprit, ground cable under floor where ground cable mounts to the frame. Check both ends of both battery cables for clean and tight connections. Check third cable that grounds block to frame. Mounts just in front of the starter and goes to frame at the idler arm.
Good luck.
most likely culprit, ground cable under floor where ground cable mounts to the frame. Check both ends of both battery cables for clean and tight connections. Check third cable that grounds block to frame. Mounts just in front of the starter and goes to frame at the idler arm.
Good luck.
Thread Starter
4th Gear
Joined: Jun 2025
Posts: 4
Likes: 2
Thanks for the response 4-vettes. We thought it might be a ground issue also and checked the battery ground cable and the engine ground. Both are good. Also looked for a possible fusible link blown but all looked good. Load tested the battery and it tested good. Good times! Thanks again.
Melting Slicks
Joined: Sep 2006
Posts: 2,809
Likes: 469
From: Wichita Kansas
Unhook the negative battery cable. Then using battery cable, hook one end to the battery negative, and the other end to a known negative source. If car starts, then your car's negative battery cable is bad.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,809
From: Cool Northern Michigan
denversdad,
I assume your battery went to a store for the load-test.
12- 13 volts is not what starts the vehicle. It's the 600 - 1,000+ crank amps that does.
The 12V will run some lights, radio, low amps, etc but will not meet the demand of the starters amps.
You can not tell the condition of any GRD wire / GRD cable just by looking at it. They must be removed, wire brushed, copper strand inspected and reinstalled.
Always disconnect the battery NEG before cleaning any electrical terminal.
I know you can't get the rear wheels up on ramps because it won't start. But you need to get at that MAIN GRD under the battery box to frame.
I assume your battery went to a store for the load-test.
12- 13 volts is not what starts the vehicle. It's the 600 - 1,000+ crank amps that does.
The 12V will run some lights, radio, low amps, etc but will not meet the demand of the starters amps.
You can not tell the condition of any GRD wire / GRD cable just by looking at it. They must be removed, wire brushed, copper strand inspected and reinstalled.
Always disconnect the battery NEG before cleaning any electrical terminal.
I know you can't get the rear wheels up on ramps because it won't start. But you need to get at that MAIN GRD under the battery box to frame.
Thread Starter
4th Gear
Joined: Jun 2025
Posts: 4
Likes: 2
Hey Kansas123 Thanks for your help. Gonna file jumper cable trick under "why didn't I think of that?" After cleaning the block to frame ground connections that didn't work I tried the jumper cable block to frame and IT'S ALIVE!! Bad ground strap! Thank you, Thank you and Thank you!
Thread Starter
4th Gear
Joined: Jun 2025
Posts: 4
Likes: 2
Hey HeadsU.P. We tested the battery under load and it was ok. Cleaned ground connections for the battery and at the block and frame. Kansas123 suggested using a jumper cable for a ground test. Hooked cable to block and frame and it worked. The block to frame cable looked good while lying on my back in semi darkness but that proved to be wrong! Thanks for your help!
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