Hi,

I’m new to the forum so please excuse me if I’m not in the right area here. I have a 1974 with a 350 and T-Tops. Last night I was driving down the road and tried to hit my high beams and must have knocked something loose under the dash (I think) because when I did, the entire car shut down. The lights went completely dark (no brake lights-nothing) and the engine shut off. Very dark road and very dark night so it was pretty dangerous. I pulled over as close to the shoulder as I could and called the cops because I was in danger of being rear-ended and potentially getting someone else hurt.

Cops showed up and I had a chance to troubleshoot the car. The ignition did nothing, still completely dead. I got under the dash and looked for loose connections where my foot may have hit. The only loose item was the small interior light under the drivers side dash. I couldn’t see any problems so I opened the hood and looked for anything obvious around the starter. Nothing there. Then I looked back inside and the interior lights had come on which meant there was power so I turned the key and sure enough, it fired right up. Weirdly, the interior lights stayed on though. When I got home I messed around with the switch which didn’t turn off the interior lights but I noticed that when I messed with the bulb and jostled it a bit the lights would flicker and when I remover it, all interior lights turned off.

all of this is a mystery. It seems like it should be connected somehow. Most worried obviously, about the complete shutdown and what could’ve caused it. happened right when I went to hit the floor high beam switch.

also a side question. My tach recently stopped functioning. No idea why... it was working and then just wasn’t.

i would appreciate any help. Thank you!

 

I would check the ground cable at the battery and where it attaches to the frame underneath.

 

Look at the firewall on the passenger side for this switch... It plugs into an orange connector mounted on the firewall.

Push the button in and see if the car starts....

This part is part of the glorious 1974 seat belt over-ride system that would not allow you to start the car if kicked out.

If it works, there is a by-pass for this.

 

When ever this happened on my old cars the first thing I would do is tighten the clamps to the battery.

 

Thank you for all of the suggestions. The car is offsite at the moment so I’ll go check on these and get back to you. Thanks for all of this!

 

Mine did that ('72) several years ago while cruising on New Years Day of all days. Turned out to be a short in a dash speaker that then blew the fusible link at the horn relay.

 

This could definitely be it then because every time I try to turn on the radio, some short causes the fuse to blow. Never thought that could lead to such a complete and catastrophic failure though. But then if this happened and that horn disable link blew, it wouldn’t be possible for everything else to magically start working again a few minutes later right? Unless that fuse link is a circuit breaker... thanks for the thought!

 

He said he lost all power.... wouldn't this relay just prevent the starter / ignition from working? I cant see them killing the whole car power via this?

I tried finding more on this seatbelt interlock debacle but all i saw was ref. to killing off the starter kinda like a neutral safety switch.

I would check the battery cables and make sure the wireharness bulkhead connector is fully seated / tightened .

Also, if a fuse-able link goes... its not coming back without you cutting it out and replacing it...

 

Thank you to everyone who offered advice. I just got the vette out of storage and I was able to determine that it was just a loose battery terminal connection. Thank you again for all of your help!

 

What is the by-pass fix for this? I have a 74'

 

What is the By-pass fix for this. Mine just died for no reason.

 

By "died" do you mean everything went dead like the OP had happen? If so, this is not the cause. not even sure why it was suggested. This seatbelt sensor system prevents the car from starting but it will not cause you headlights and gauges to go dead. Thats a battery connection or burned fusable link issue
I disabled my seatbelt sensors by simply unplugging the sensors located in the bottom of the seats of my 74 but there is a jumper you can make if you suspect the rest button does not work on the relay.

The most common cause of the engine not starting or dieing but still having power and turning over on c3s is the HEI module but you will not have one on a stock 74 distributor. I replaced mine with HEI and my module has died twice already.

 

actually.... I changed over to HEI about 1 month ago

 

did you run a new dedicated 12g wire from the ignition port on your underdash fuse panel or are you trying to use the old resister wire from the old distributor? because the resistor wire will cause problems like this.

 

#1 Buy a new one from Willcox

#2


#3

 

Nope

 

ok well you likely need an hei ignition module at this point and then you will want to supply a dedicated true 12v to the distributor to avoid another failure.
Good luck.

 

I thought it died from a loose battery cable a year ago

 

Im responding to the person that revived this thread thinking he may have found his solution here to his issue but its more likely he has a bad module. I learned from experience on this issue and have read its a common mistake.

 

What if I just go back to the old style and throw HEI in the trash??