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Dash light problems when headlights on 1992

89blackvette

Well-known member
Joined
Feb 7, 2003
Messages
178
Location
Sylvester, Georgia
Corvette
1992 white Coupe
When I purchased the car it has an after market remote entry system installed by the previous owner with no remotes. It was a very crappy install with some wires simply twisted together and taped. I removed it and reconnected all the cut wires with solder and shrink tubing insulation. The problem I am going to describe was in the car when I purchased it. Dash lights work great and the photocell dimmer works great with headlights or parking lights off. When the headlights or parking lights are turned on the dash lights, including the radio and climate control lights go dim to the extent that you can not read the gauges, however the photo cell in the information center works, you can shine a light on it and the lights all get bright. Also the interior courtesy lights do not com one with the dimmer switch on the headlight switch. I can move the dimmer slider on the light switch to a point where the courtesy should come on and the dash lights go full bright, it is a very small area on the simmer slider., I have replaced the dimmer gizmo under the dash at the steering column and the light switch with no success fixing this. I have a Factory Shop Manual but not being an electronics expert I simply can not figure it out. My basic question is there a way to short a couple of wire at the light switch connector on the back of the light switch to just have full bright instrument lights all the time? I have of course checked all fuses, checked the headlight switch with meter and found all connections and wiring correct to it. Checked under the dash for broken or disconnected wires. Any more suggestions? hanks for your time.
Mike
 

ecss

Well-known member
Joined
Nov 27, 2004
Messages
649
Location
Windsor Mill, MD
Corvette
89 Brilliant Red Metallic
I'm looking at a 93 service manual so I can't say the colors of the wires of the
headlight switch are the same as a 92.

Connector C1 at the headlight switch has the following wires.
Pin A Purple/White
Pin B White
Pin C Red/white
Pin F Black wire *************
Pin G Brown
Pin H Orange
Pin J White
Pin K Yellow
Pin L Red

The Black wire is ground and goes to the driver side kick panel where the wiring harness from the driver side door comes into the interior of the car.

From your description of the problem the Black wire is not grounded.
When you turn the headlight dimmer switch so the interior lights come on, this Black wire provides the ground path for the interior lights.

It also provides the ground path for the resistor part of the dimmer switch.

Disconnect the negative battery terminal.

Disconnect the plug at the headlight switch and with an ohm meter
verify the Black wire has continuity to the disconnected negative battery cable.
 
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89blackvette

Well-known member
Joined
Feb 7, 2003
Messages
178
Location
Sylvester, Georgia
Corvette
1992 white Coupe
Thank you I will check that tomorrow. How in the world did the designers and engineers manage to come up with the wiring for these cars? They took simple circuits and intertwined them so that if one thing goes wrong it has repercussions throughout the electrical system. Perhaps there is a level in Dante's Inferno for them where the have to trace wires that have continuous dead ends and loop backs. Thanks again for the reply.
Mike
 

89blackvette

Well-known member
Joined
Feb 7, 2003
Messages
178
Location
Sylvester, Georgia
Corvette
1992 white Coupe
Checked the ground wire as suggested and have continuity from black wire on switch and ground cable at the battery. Same symptoms with 2 different headlight switches. Any other suggestion. Thanks for the replies.
Mike
 

ecss

Well-known member
Joined
Nov 27, 2004
Messages
649
Location
Windsor Mill, MD
Corvette
89 Brilliant Red Metallic
Do the courtesy lights come on when you open either door?
You need to place a piece of tape over the photo cell if you're working in daylight
because the photo cell can disable the courtesy lights.

If the courtesy lights work, and you close both doors do they time out after about
20 seconds.

If they do close both doors and wait for the lights to time out.
With the harness plug disconnected from the headlight switch, if you
ground the White wire, the courtesy lights should come on. This simulates the
operation of the dimmer switch

You may have multiple problems so you need to fix one problem at a time.

If the courtesy lights don't work at all, verify the RH CTSY 5 amp fuse in the passenger side end of dash isn't blown. I'm looking at a 93 manual.
 
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89blackvette

Well-known member
Joined
Feb 7, 2003
Messages
178
Location
Sylvester, Georgia
Corvette
1992 white Coupe
Courtesy lights work OK with doors. After looking at the manual the white wire connects to S232 (that I have not found yet) looks like grounding to all courtesy lights are here. Book says it is located to the left of the passenger glove box so I will have to remove the underd0 ash cover on that side and look for it. I have not found any broken wires under the dash on driver side. I will try your suggestion next. if they work then I will know it is the white wire. Thanks guys for the replies, any suggestions are welcome. This is the last gremlin to fix on this car, it has 54000 miles on it. It show age wear but runs and drives great. Again THANKS.
Mike
 

ecss

Well-known member
Joined
Nov 27, 2004
Messages
649
Location
Windsor Mill, MD
Corvette
89 Brilliant Red Metallic
Since you have the hush panel off of the driver side, look at the foot well lamp connector.
Connector plug should have a Orange wire which is hot at all times. The white wire on the connector is the one that gets grounded by either the Courtesy lamp relay or the Headlight
switch.

You should measure zero resistance from the White wire at the headlight switch to theWhite wire at the driver side foot well lamp White wire connector. If not the White wire has a break in it.

If you can't physically trace the White wire from the headlight switch to the splice,
I'd just solder a wire from the White wire at the headlight switch plug to
the White wire at the foot well lamp.
 
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89blackvette

Well-known member
Joined
Feb 7, 2003
Messages
178
Location
Sylvester, Georgia
Corvette
1992 white Coupe
It has to be the headlight switch !!! Interior lights come on when shorting the white wire to ground at the switch connector. I checked both switches with meter and found both bad between white wire and black wire. I will try to find a GOOD headlight switch. Thank you guys for the help and hand holding. Any suggestions where to get a switch?? THANKS
Mike
 

89blackvette

Well-known member
Joined
Feb 7, 2003
Messages
178
Location
Sylvester, Georgia
Corvette
1992 white Coupe
EC55,

Thanks for the suggestion, I checked and there is continuity between the white wire at the switch and the foot well light. It is pretty much bas switches. I got the second switch from local junk yard. What are the chances of having 2 bad switched. pretty unlikely but I have them. Any suggestion where to get a switch? I see no one seems to have a new one in stock. I do see one on Ebay and may get it. My electrical trouble shooting is just that I shoot in dark. THANKS GUYS.

PS ordered the one on Ebay
Mike
 
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ecss

Well-known member
Joined
Nov 27, 2004
Messages
649
Location
Windsor Mill, MD
Corvette
89 Brilliant Red Metallic
So both headlight switches are bad?
Both the courtesy switch position
and the dimmer/resistor portion of the headlight switch?

Are you positive the connector pins aren't pushed out of the connector
at the headlight switch?
 
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89blackvette

Well-known member
Joined
Feb 7, 2003
Messages
178
Location
Sylvester, Georgia
Corvette
1992 white Coupe
Yes I am positive on that, pins are not pushed out of the connector. I checked both switched with ohm meter and got nothing between pin F (ground) and pin B the white wire to the courtesy lights with the ewitch slider move to the courtesy light position. I will report back on this thread when I get another headlight switch. Thanks again for the replies.
MIKE
 

89blackvette

Well-known member
Joined
Feb 7, 2003
Messages
178
Location
Sylvester, Georgia
Corvette
1992 white Coupe
FIXED!!! Ebay light switch fixed the problems. I now have courtesy lights using the slider on the light switch, instruments light with parking or headlights on and dimmer slider works. Thank all of you for the kind informative replies. I am not much at electrical trouble shooting but I do follow instructions well. AGAIN THANKS !!!
Mike
 

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