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Dash Lights

R

rhatala

Guest
Hello all, this is my first post and I am newbe Corvette owner.

The dash lights on my 74 Vette have not worked sinces I got it.
Have taken the dash apart and found that the socket that plugs into the light switch appears to have heated up at some time and it looks like a wire may be missing (no wire to one of the contacts on the light switch and the place where the wire would be is burnt a bit). I assume that the dash lights would be controlled by the light switch (dimmer). Anyway, not sure where to look or what to do at this point. Any help and direction would be appreciated.

Thanks
Bob
 
Joined
Aug 29, 2001
Messages
3,222
Location
Norcross, Georgia, United Stat
Corvette
2017 Arctic White Grand Sport
Bob,

I just had mine apart on my 77. The light switch controls the dash lights at the first and second indent and by dimming.

I have what appears to be 3 ground circuits for the dash lights; the center console, the tach and the speedo. The lights in each are the same with a hot wire connected to the plug and a common ground from the plug to the cluster when in placed and then to ground.

If you have the same setup, and one or two or three of the circuits are not coming on, I would suspect the light switch plug and/or the wire or the light switch. If only one of mine were not coming on I would check the grounds.

Good luck and welcome.

Bob
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Look at the post

Wiring help for a 68

Blasterrod & I have been going thru this for some time...

Might be a good read, the 74 sys is not much different than an 68, and the color code info has been out of my 73 shop manual

Mike
 
R

rhatala

Guest
Thanks for the response...

All of the dash lights have a single gray wire coming from the harness. I do see the contacts 1 & 2 on the light switch and both have a wire connected to it via the light switch plug connector. How do I check the ground connection? Any other suggestions as to what to check/do next?

Bob
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Read the ENTIRE post

Mike
 
C

cmegga

Guest
fuse box??`

Had the same problem on my 81 .. after numeriuos hours behide the dash and a new light switch I acomplished nothing.

Took it to the shop and they pulled the fuse box. The fuse was entirely melted into the box. We riged up a new external fuse. No problems since
 
Joined
Aug 29, 2001
Messages
3,222
Location
Norcross, Georgia, United Stat
Corvette
2017 Arctic White Grand Sport
On the 77, the grounds on the speedo and tach are easy to check. I'm assuming you checked to make sure the grounds on the speedo and tach are attached. Simply attach a test light to a hot wire and touch the frame around the units or the ground wire itself. If the light lights, you have ground.

The principle is the same for the center console but you have to figure out which of the wires on the plug is the ground ( I don't recall which one it is). Once you do, the process is the same.

If you don't get a ground this way, you will need to follow the ground wires to their ground source.

This is an eash check but I suspect that your problem is the burnt wire, socket and switch. That says electrical short to me. The switch can be bought at many places but I'm not sure on the plug.

Bob
 
R

rhatala

Guest
Re: Look at the post

Mike, this is all I received.

Where do I go to read the ENTIRE post?
I am new to this message board and do not know my way around.
Need a little newbe help here....

Bob

vigman said:
Wiring help for a 68

Blasterrod & I have been going thru this for some time...

Might be a good read, the 74 sys is not much different than an 68, and the color code info has been out of my 73 shop manual

Mike
 
R

rhatala

Guest
Thanks to all

Thank you one and all for your help so far.

After reading the thread from Vigman, I tested the electrical.

Red wire is HOT

The small fuse is good

With ignition switch on, Ground to all fuse contacts have current EXCEPT the short small fuse for dash lights.

Turned the lights on via light switch, still nothing to either side of the gray fuse

Appears that there is no current to the short fuse.

Any suggestions?

Bob
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Probably the resistor

Up in the dash headlight switch.. I need to read my own post again ...


+12 goes to the headlight switch wiper (red) of the dimmer ( big nichrome wire wound resistor) the output of the resistor is a Dark Green. give this POT a good scrub and see if the lights flicker. ( REMEMBER PULL THE LIGHT SWITCH OUT 1 CLICK)

This goes down to the fuse panel ( 4 amp fuse )

So you should see the dimmer action on the fuse panel. There is a small male spade lug in the fuse box to the left of the fuse to test it.

So in logical order
Batt to red wire on dimmer switch assy one side of winding.

Wiper of pot to dark green wire down to fuse box 1 side of fuse

Other side of fuse to grey wire to feed ALL instrument lights

On the dimmer there are 3 connection points IN A ROW

_____________
.........Red.X.. X( not this outside one)
DarkGreen.X < Shaft of switch
.........N/C.X
_____________


The two outside ones (Red & N/C) are the winding of the Nichrome wire.. this should measure as a fixed resistance, I'm guessing about 50 ohms.

The center connection point is the wiper(Dark Green). So with your Ohm meter across the middle & one of the ends as you turn the knob the resistance should change

Repeat for the opposite side.

Now try the following
Reconnect the headlight switch
I'm assuming you are using an automotive style test light ( Cliplead on one end..sharp pokey thing on probe)

The cliplead goes to ground
The pokey tip goes to the Dark Green
Pull the lights to the first stop ( on the switch )
the testlight SHOULD LIGHT! and as you twist the knob it should dim.

Try this

Mike
 
R

rhatala

Guest
Well, it has been some time since I have time to look into this problem. I pulled the fuse block and there didn't appear to be any corrosion (boy what a chore to get it back in place.

I next took the tape off the wiring harness and did find where all the dash lights come together at a soldered connection. I also found a workaround that someone did to provide power to a light on the rearview mirror. I can tap into this wire, however I would need to somehow wire it into the riostat dimmer for the dash lights to come on only when the lights are on. Any way that I might be able to do this?

I know this is not the preferred way of wiring, but I am not a pure Corvette nut that has to have everything original. I am more interested in having the wiring work.

All suggestions are welcome.

Thanks to all.
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Did you get the dimmer working yet?

Or is that still on the fritz?

Mike
 
R

rhatala

Guest
Have not checked the dimmer yet. I won't be able to do that until next weekend.

Bob
 
R

rhatala

Guest
Well, the verdict is in. The problem ended up to be the reostat. I found that the wire wound reostat had a broken wire and the reostat had no juice going to it, therefore no juice to the dark green wire. choice now is to replace the light switch or rig a circuit to the dash lights.

Thanks for everyone's help. It's Miller time.

Bob

:beer
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Buy new switch

No reason to BUBBA it.


Mike
 

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