I have recently been experiencing an intermittent electrical issue with my 71 350 engine, 4spd vette, that has turned permanent. I have a fresh battery with the correct voltage, but no electrical to remainder of car. I cannot turn the lights or flashers on. I was getting intermittent electrical with the ignition switch on, but that has also gone away. I have read about the fusible link, and neutral safety switch, but i thought that this issue would still allow me to operate the lights. Any insight or clarification on my diagnosis would be greatly appreciated.

 

did you check the ground cable under the battery compartment where it attaches to the frame? Did you use a voltmeter on the positive cable to where it attaches to the starter?

 

Electrical! I'd rather have raccoons in the storage compartments!

It can be as simple as an internally rotted/corroded ground cable.......or a loose or corroded battery negative/ground cable at the battery connection or at the frame connection.

Using a D.C. voltmeter here are a few areas to check first:

does the main lug on the starter solenoid have 12 volts?

does the main lead to the fusebox have 12 volts at the firewall (you will have to probe the lead)

does the ignition fuse have 12 volts?

 

thanks for the reply MelWff. Ground cable to the frame is solid and i have 12.5 volts at the starter.

 

Yeah, i hear ya, electrical issues are certainly troublesome.

I have voltage at the starter, and the fuse box. I will need to check the ignition fuse. I am leaning towards the neutral safety switch on the clutch pedal. After leaving the car set for a while, when i turn the ignition key, i can hear my air handler start, but when i go to full turn of the ignition switch i get nothing and the air handler noise is gone. When i try this again, no air handler noise. After sitting a while this process repeats. Very strange. How do i know if my neutral switch is bad?

update: i ran a test with the ignition on and re-checked the voltage across the battery and when i applied the test probes on the multimeter, the air handler turned on....not sure what's going on here.

thanks.

 

You HAVE TO make sure that your battery cables are CLEAN AND TIGHT.

If you battery cables have been butchered by someone who installed some crappy replacement ends..you can have an issue with them.

As for your "clutch safety switch" and NOT a neutral safety switch...which your car does NOT have due to having a manual transmission....when you turn your ignition key all the way to try to crank your engine...you can check the purple wires that plug into the clutch safety switch ( down by your clutch pedal) and see it you get battery voltage at ONE of the two wires. IF you press the clutch down...the switch will "close" and allow the current to pass through the switch and go to your starter solenoid.

IF you get the voltage to go through the switch...but it still does not crank. Then go to your starter and check to make sure you are getting battery voltage at the purple wire on the solenoid when you press the clutch pedal. IF you do and still nothing...the I would disconnect the negative battery cable and then go back to the solenoid and remove the battery cable from it and make sure the stud that is is attached to is tight.

There is no fuse for ignition in the fuse panel...and also no fuse for your headlights. The headlights are getting power from the solenoid ( battery terminal) and the wire is fusible linked to protect the system.

You need to get wiring diagram. well worth the money.

DUB

 

10-4 on the wiring diagram, i have been pulling bits and pieces up online, but its not the same.

If the headlights get power directly from the selenoid, then they should function whether the clutch switch is on/off, is this correct? In my case they don't. I will check battery terminal connections, but they appear to be ok and I am getting voltage to starter, alternator and fuse block.

 

There is also a ground cable passenger side engine bay under the area of the motor mount. Grounds the engine to the frame. Also check your horn relay driver side engine bay over the wheel well.

 

You will have to blow these up a bit, but..









If you just start at the battery, and trace BOTH Positive and Negative cables/wires out and to your malfunctioning item, you may find your problem. I'm not a wizard at this work, but I was good at it enough to be employed by the Navy as a Crewchief/Flight Engineer for over 25 years. If I can do it, anyone can do it. Good Luck.

 

Thansk Cavu2u much appreciated.

 

Well, the issue is resolved with a lot of poking around and testing. The confusing part about this was that i was getting good voltage at the battery and at the starter, so i figured i had good connections there and mistakenly ruled out anything associated with battery to starter. I decided to run some tests with the ignition key engaged and initially suspected the clutch switch, but i was unable to operate the lights. Then i went back to the battery with the ignition switch on and when i applied my multimeter leads to battery leads (not posts) i wasn't seeing 12 volts. I pulled off the leads and noticed some corrosion on the underside of positive lead that wasn't visible from above. That was it. Thanks to everyone for all your efforts in helping and I learned that the problem usually lies somewhere you've overlooked.

 

YEP!!!! Which is why I mentioned checking your cables. When you wrote that "things" changed when you went back and were checking voltage at the battery and it went out...that let me know right there that you had an issue at the cable...where 90% of electrical problems can be fixed when it is current load related....from what I have experienced.

Glad you have is resolved.

DUB

 

Ahhh yes: K.I.S.S.
Happens to all of us once or twice in our endevors.

Congrats on the find. Great feeling ain't it.