66 Electrical Problem

[Hector G.]

Turns out the battery was not the problem. First, some background. The 66 has been crated in my garage for the last 8 months. I pulled the car out of the crate about four times during that period and drove it for short distances each time. The last time I did this, one month ago, I pulled into a gas station, turned off the ignition and after filling up, couldn't get the engine to start. On turning the key, one could here a clicking noise. Fortunately, the gas station, approximately two miles from home, is constructed on a slight uphill and I was able to roll out of the station, and jump start the car in 2nd gear. First time I've ever done this. Got home and that's were the car is now.

I was hoping that the battery was the issue. Purchased a new battery yesterday, installed it, told my wife to get ready for a drive, and misfortune struck. The courtesy lights in the car turned on when the door was opened, I turned the key, and nothing. A slight click and know the courtesy lights would not turn on anymore. I checked the contacts on the battery cable, reconnected and power to the car was restored. I checked the gauge lights, no problem. When I engaged the headlights, once again the power was out. A recheck of the cables and the power was back on. But for the headlight issue, I thought this might be a solenoid issue. Any thought on the topic would be greatly appreciated.

Hector

[William C.]

Re: 66 Electrical Problem

Poor connection, start with BOTH ends of the Battery cables and work up to the junction at the front of dash from there. Check both power and grounds. If you get to the connection under the steering column check carefully on both sides of the connection carrying power via the red wire. YOu should find it in that series of steps. If connection at the steering column is the issue, loosen the fuseblock, and add a jumper 12 ga wire to eliminate the terminal. You can hide the jumper wire behind the fuseblock and no-one will notice, just make sure to avoid shorting it out on anything. If that is the Problem, you can thank Wayne Womble for the fix info.

[Jack H.]

Re: 66 Electrical Problem

Starter motor heat soak can cause those symptoms. When the starter gets extremely hot, the force needed to overcome the solenoid's return spring and engage the Bendix drive is too much for the electrical system to handle. That's one of the reasons various years of Corvette incorporated heat shielding on the starter motor PLUS the solenoid spring was 'special' for Corvette applications (slightly lower spring force than on equivalent passenger cars).

You diagnose this by recreating the condition(s) where the starter won't engage, then give the starter motor + solenoid a SHORT bath with a garden hose (WATCH OUT that you don't spray and wind up cracking the RH exhaust manifold.

If the car then IMMEDIATELY cranks, you can pretty much conclude you're fighting a starter heat soak problem. The 'fix' is to pull your copy of the AIM and insure you have all the factory original heat shield components installed.

Then, if that doesn't give full relief, replace the solenoid's return spring with a correct one. Note, most of the off-the-shelf starter rebuild kits include a fresh new solenoid spring and these are 'omnibus' kits intended to service any/all similar GM starter motors....

Last, if memory serves, there was a GM service bulletin on this that advized, in a pinch, you could 'make' an incorrect solenoid starter return spring work by cutting 1.2 winds off one end to reduce the overall length and weaken the spring's overall force profile.

[Jeff A.]

Re: 66 Electrical Problem

Sounds like a typical junction box connection problem.

The little connectors just were not meant to last 40 years.

Give your car an alternate 12 volt route.
run a black wire from the horn relay, around to the little 2 prong relay/connector under the dash. You will never have that problem again.

[Gary S.]

Re: 66 Electrical Problem

When I had various electrical gremlins with my 66 (not starting related) I eventually traced it to the firewall junction blocks. To make this simple, I took them apart carefully, fearing age embrittlement of the plastic, and cleaned the male and female contacts thoroughly. Once cleaned and dry, I reconnected them and had no further electrical related issues.

Gary

[Hector G.]

Re: 66 Electrical Problem

Thanks guys. Once again, you've been a great help. I'll work on it this weekend. I'll let you know how things turned out.

Hector

[Joe T.]

Re: 66 Electrical Problem

I have a somewhat similar problem. When I try to open the headlight doors it immediately kills all power. Not when closing them. When I wiggle the main electrical connector on the fire wall, the power comes on. No fusses are blown. I know it could be a switch issue. But why does it cause the main power connection to open then recover when wiggling the main electrical connection?

[Edward J.]

Re: 66 Electrical Problem

Joe if you unplug the firewall connector(s) you likely see green corrosion from moisture over the years. Or one of the spades has spread open, you need some spray electrical contact cleaner. And a small brush maybe try a old tooth brush.

[Joe T.]

Re: 66 Electrical Problem

Why does it happen when trying to open the headlight doors? Does a short or ground case the contact to open?

[Joe T.]

Re: 66 Electrical Problem

My problem resolved. When I had the dash out, the up wire (yellow) in back of the headlight door switch puled enough to short out with the ground. I replaced the socket. Also cleaned the main terminals on the firewall. Thank you.

[Edward J.]

Re: 66 Electrical Problem

Nice job Joe. Finding electrical problems can be pain full @times.