Starting Issues
Thread Starter
Intermediate
Joined: May 2012
Posts: 48
Likes: 0
Starting Issues
A thousand pardons for probably bringing up a subject that has been addressed ad nauseum on these 74 Vettes. I did search but didn't find the answer I needed. The engine won't crank. The battery is good and the starter is functional. I followed the diagnostic chart and was able to get it to crank and start by removing the seatbelt override relay and jumping the purple wire. When I went to check the next step 12v's at the "B" terminal blk/grn wire it's dead. In looking at the wiring diagram it seems to lead to the seat belt warning switch? Where is this switch located and is it also possible the ignition switch is faulty? Thanks much! Brett
Le Mans Master
Joined: Aug 2006
Posts: 7,431
Likes: 1,561
From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
Hi and welcome!
You will find some information on that circuit on page 12-43 and a step by step troubleshooting guide starting on page 12-62 in the 74 service manual if you want to restore it to factory specs.
You can bypass the entire circuit by connecting 12 light green/black to 12 purple at the override relay (mounted on the orange bracket under the hood).
You can bypass the entire circuit by connecting 12 light green/black to 12 purple at the override relay (mounted on the orange bracket under the hood).
Thread Starter
Intermediate
Joined: May 2012
Posts: 48
Likes: 0
No luck with that. Starter solenoid will click and that's all. Must be in the starting circuit, now starting to suspect the ignition switch because when I apply 12v to the purple wire at the override relay it will crank right up. Any thoughts?????
Drifting
Joined: Jul 2011
Posts: 1,697
Likes: 139
From: Syracuse NY
My stupid mistake number 4,567,989:
Is the car automatic or manual transmission?
I had a piece of carpet under my clutch pedal that wasnt letting me depress the clutch far enough to trip the safety switch. Took me 3 days to figure that little doozy out....
automatic.....neutral safety switch....
Both these options are cheap, easy to diagnose and often overlooked.
Is the car automatic or manual transmission?
I had a piece of carpet under my clutch pedal that wasnt letting me depress the clutch far enough to trip the safety switch. Took me 3 days to figure that little doozy out....
automatic.....neutral safety switch....
Both these options are cheap, easy to diagnose and often overlooked.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
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
Le Mans Master
Joined: Aug 2006
Posts: 7,431
Likes: 1,561
From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
No problem, you keep asking! You see there is a brotherhood between Corvette owners and as you see, everyone on the forum is eager to help.
Here's a page from the AIM.
74 is a fun car to play with, do you have the 74 service manuls and the AIM yet?
Le Mans Master
Joined: Aug 2006
Posts: 7,431
Likes: 1,561
From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
Have a helper in the seat and with a foot on the brakes just in case it's in gear!
My best guess, see if you have power to the NSS.
Basic starter circuit:
Thread Starter
Intermediate
Joined: May 2012
Posts: 48
Likes: 0
I removed the NSS last night, bench tested it and had continuity where and when it should be. So back out to the 74 this morning and tested the purple/white wire for power when the key is in the start position and - NADA. So now to put the NSS back in (would have been much easier if I had just left it in and unplugged it)! Oh well, I'm on a learning curve! And then I'll drop the column and remove the ignition switch. It's funny when this first started happening I figured it would probably be the ignition switch and then I started reading the manual.....Should have stuck with my gut feeling. This is my wifes car and I sure hope she appreciates it when it's all said and done. I tried to talk her into one that someone else had already ressurected/restored but she wanted to work (me) on this one. Can't wait until we finally get her out on the road. A lot of work ahead but it'll be worth it in the end but will still keep our eyes and ears open for one that's already finished too. Thanks to everyone who replied and rest assured I'll be back frequently.
Brett
Brett
Thread Starter
Intermediate
Joined: May 2012
Posts: 48
Likes: 0
I picked up a manual from EBay that covered half a dozen 74 chevrolet models including the Corvette. It's not bad but clearly not definitive enough. I believe I would be better served with the AIM and correct manual. Where can I get these? Or, is there someone out there who has sold there 74 that would like to sell their manuals?
