Joseph Koski

Had this listed in general, put hoping for some assistance.
Ok, a strange thing happened, I had to replace my heater core and it took me some time to finish putting the center console back in. Well, I got it back in last night and now I have no headlights, gauge lights or interior lights?? There was a spark while I was disconnecting the battery. What could be the cause of this mysterious issue?? Bad fuse? Switch? Bus link fuse? I am at a loss. Oh, this is a 1974 coupe, and all lights worked before I placed the center gauge cluster back in. Thanks in advance for any assistance provided.

Alan 71

Hi JK,
To begin...
Is it just the interior lights and headlights that aren't working?
Can you start and run the car normally?
Regards,
Alan

Joseph Koski

Hey Alan thanks for the reply, I can drive the car with no issues. I have no interior, gauge, headlights or alarm horn now. Could this be a rely or several fuses? The marker lights and brake lights work.

Alan 71

Hi JK,
I'd start by checking the fuses for the dash lights.
There's not a fuse for the headlights... there's a breaker in the headlight switch to protect the headlight circuit....but, it should re-set itself... unless the fault remains.
Hopefully someone with more electrical understanding than I have will join in and offer you some suggestions.
Regards,
Alan

MelWff

you have two threads going with the same issue and on the other thread you stated,
"While getting everything ready I was working on disconnecting the battery when the clock wire grounded and sparked."

So where was the spark, at the battery when you disconnected it or you grounded a hot lead at the clock? If the hot lead at the clock you could have fried a wire harness.

Joseph Koski

Hot lead at the clock. But if the harness is bad won't the radio and gauges stop working?

Peterbuilt

Check the CLK LTR CTSY fuse.
Top left side if the fuse box.

Joseph Koski

I will check this one when I get home tonight.
Hopefully, that's what the issue is.

DUB

That fuse (CTSY CLK) will correct your interior lights and your clock if it has blown...but will do nothing for the gauge lights and headlights.

Do you have a wiring diagram for your Corvette???

DUB

Joseph Koski

I don't think I do. Will have to look at all the paperwork that the previous owner gave me.

Peterbuilt

74 schematic:
https://docs.google.com/viewer?a=v&p...TRkNTFkY2E0NmM

Joseph Koski

Ok, quick update, I replaced the CTSY CLK fuse and the INST LPS fuse today and I have all my interior lights back. Clock still not working but it didn't really work before. So now onto figuring out why the headlights will not work. Is it possible that I may have shorted all four headlamps? Also, the Bright indicator does not work and the Headlight console light will not come on once the headlight switch is pulled out. Still learning my way around this car. Thanks for all the help thus far.

Peterbuilt

With the headlight switch pulled out to the second click:
Check the dimmer switch connection for 12 volts at the BLUE wire.
If you have 12 volts here then jumper BLUE to GREEN.
If headlights still do not light up check the BLACK wire on the radiator support for a good ground.

DUB

And if you have 12 volts on the BLUE wire and jump the BLUE wire to the TAN wire... that will make your low beams work.

If you do not have 12 volts on the BLUE wire....then it is possible that the RED wire has a blown fusible link.

DUB

Joseph Koski

Ok, checked the dimmer switch this weekend and I have no voltage at the BLUE wire.
Where do I go now?
Thanks for all the help so far.

DUB

I assume you pulled out on the **** of the headlgith switch when you checked the blue wire for voltage???

You need to check and see if the RED wire that is in the connector of your headlight switch has 12 volts on it. THIS WIRE is critical!!

The ORANGE wire should also have 12 volts on it.

IF the RED wire has 12 volts...pull the **** and check the BLUE wire where it is in the connector you have plugged into your ehadlgith switch.

DUB

Joseph Koski

DUB, Don't mean to sound dumb. But are the RED and ORANGE wires a constant 12 volts?
So I guess this means I have to pull the dash, again. DANG!
Thanks

DUB

If you looked at the link in POST #11 and look at the wiring diagram....IF the fuse is good...the orange wire should be 12 volts.

FYI..I would NOT pull the dash to get to the headlight switch.

Lowing the steering column and gettign the speedo/tach panel loose enough so you can pull it away from the door hinge area and see the wiring and get to it is possible ...because I can do it this way all the time. it is tight...but it saves me gobs of time not having to deal with all of the light bulbs, cables, etc.

DUB

Joseph Koski

Ok so I pulled the dash part way out last night and I have 12.5 volts to both the Orange wire and the Red wire. But I have no power to the dimmer switch. The courtesy lights work, the parking lights work, could this be a headlight switch issue?
Thanks

DUB

Now with the headlight switch connector exposed. You have a LIGHT BULE wire in it....correct???

IF so...that light blue wire is the light blue wire that goes down to your dimmer switch.

When you pull the headlight **** all the way out....the LIGHT BLUE wire should get battery voltage on it. Check that.

IF it does BUT you do not have battery voltage on the LIGHT BLUE wire at the dimmer switch...you have a broken or 'OPEN' wire somewhere.

IF you do not get battery voltage at the LIGHT BLUE wire ...then I would have to say that the headlight switch is bad.

NOW...you can quickly test this by taking a wire ( stripping the insulation off the ends a little bit) and jumping from the RED wire to the LIGHT BLUE wire when you have your headlight doors up and see if your headlight lights up. Make sure you use a large enough gauge wire and do it for a few seconds

IF it does not...then the LIGHT BLUE wire is OPEN. OR...you check to make sure you are getting battery voltage at the dimmer switch's LIGHT BLUE wire and if it is present there. Then you have to check to see if the TAN or LIGHT GREEN wire is getting battery voltage at them.

IF you are getting battery voltage at the TAN and LIGHT GRREN wires at the dimmer switch BUT your headlights are still not working. Your wires to your headlights are OPEN.

This is assuming that your headlight connections at the bulbs are good and the black wire in them is GROUNDED.

DUB