Dash lights not working
Thread Starter
Burning Brakes
Joined: Apr 2007
Posts: 1,028
Likes: 1
From: SOUTH ELGIN IL
Dash lights not working
I've been trying to track down the source of my dash lights short for some time with no luck. Today I got out the voltmeter and started running thought the connections. First, me gauges are all functioning normally. I checked the fuse block for voltage and found that with the ignition off I got constant power to one slot (BAT) as expected. However, when the ignition is turned to the AUX position I get 12V to each slot with a fuse in it except for the slot labled "INST LPS". Also, I notice that the light bulb wires are all gray and crimped together behind the radio. There is a beige wire that runs out of the crimped gray ones and runs across and then it appears to run through the firewall just above the fuse block. So far I haven't been able to find it in the engine compartment.
Anyone have a wiring diagram? Recommendation on place to buy a wiring diagram? I'm starting to think someone got creative...
Anyone have a wiring diagram? Recommendation on place to buy a wiring diagram? I'm starting to think someone got creative...
Racer
Joined: May 2005
Posts: 417
Likes: 0
From: Red Deer Alberta
I want to mention too, the only way I got my dash lights to work was to run multiple ground wires from any metal in the dash containing a bulb to the support bar under the top dash pad. I don't know which one was the cure, but I had enough.
JR
Le Mans Master
Joined: Mar 2001
Posts: 6,640
Likes: 287
From: Ann Arbor Michigan
Here's a very good wiring diagram for a 78'. It should be close to your 74.
Gary
http://www.corvetteforum.net/c3/tune...l/index6.shtml
Gary
http://www.corvetteforum.net/c3/tune...l/index6.shtml
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Thread Starter
Burning Brakes
Joined: Apr 2007
Posts: 1,028
Likes: 1
From: SOUTH ELGIN IL
Fuse definitely not hot, which was my initial concern. Recommendation above is to turn the **** counterclockwise to "on" while lights are on and see if it heats up for me. I'll try that later today or tomorrow...
If that thing should be hot anytime the lights are on I definitely have a problem.
If that thing should be hot anytime the lights are on I definitely have a problem.
Safety Car
Joined: Apr 2000
Posts: 3,802
Likes: 61
From: Wichita KS
Fuse definitely not hot, which was my initial concern. Recommendation above is to turn the **** counterclockwise to "on" while lights are on and see if it heats up for me. I'll try that later today or tomorrow...
If that thing should be hot anytime the lights are on I definitely have a problem.
If that thing should be hot anytime the lights are on I definitely have a problem.
cc
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
I thought I had my dash light problem solved. The ywould stay on when the car was not moved. When Istarted to move and the car got jostled around it blows the fuse. I had the console dash out and secured up all the wires and grounds. Drove it last week for about 40 minutes and the lights stayed on. I then hit a large rut in the road and they went out. I guess I did not find them all. 
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
I thought I had my dash light problem solved. The ywould stay on when the car was not moved. When Istarted to move and the car got jostled around it blows the fuse. I had the console dash out and secured up all the wires and grounds. Drove it last week for about 40 minutes and the lights stayed on. I then hit a large rut in the road and they went out. I guess I did not find them all.
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
Pro
Joined: Mar 2005
Posts: 683
Likes: 4
I thought I had my dash light problem solved. The ywould stay on when the car was not moved. When Istarted to move and the car got jostled around it blows the fuse. I had the console dash out and secured up all the wires and grounds. Drove it last week for about 40 minutes and the lights stayed on. I then hit a large rut in the road and they went out. I guess I did not find them all.
Good Luck
Steve
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
It's most probably the light switch itself. What happens is when you turn the **** it will either brighten or dim the dash lights. The way this works is there is a what is called a wiper or a piece of metal that is in contact with a small coil spring. What happens is there becomes a gap between the wiper and the spring and this is what causes the fuse to blow. You mentioned this happens when you hit a bump or the car gets jostled.
Good Luck
Steve
Good Luck
Steve
Drifting
Joined: Aug 2005
Posts: 1,430
Likes: 8
From: Hamilton NJ
The coiled spring rheostat in the light switch that dims the lights can cause lots of problems...overheating, the wire can split and lose continuity, others.
I had no dash lights. When I checked the switch it had a bad rheostat (split wire from overheating). I bypassed it by moving the green feed wire to the adjacent spade. The green wire, if I recall correctly, is routed to the INST LPS junction in the fuse block. The dimming function was lost but the lights came on full when the switch was pulled.
Move the green wire to the open slot on the left to test or bypass dimmer:
I have since replaced the switch and put the green wire back in the center slot; all works perfectly.
I had no dash lights. When I checked the switch it had a bad rheostat (split wire from overheating). I bypassed it by moving the green feed wire to the adjacent spade. The green wire, if I recall correctly, is routed to the INST LPS junction in the fuse block. The dimming function was lost but the lights came on full when the switch was pulled.
Move the green wire to the open slot on the left to test or bypass dimmer:
I have since replaced the switch and put the green wire back in the center slot; all works perfectly.
Last edited by Wuttin; May 28, 2009 at 08:07 AM. Reason: corrected wire placement
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
IMO that overheating is from a bad connection on the unused spade next to the green wire spade-the unused spade is the feed for the rheostat which itself gets its feed from the brown wire spade.
I now on brand new switches solder that bad connection actually I solder 2 places.
edit- the green wire in the pic is in the correct location
I now on brand new switches solder that bad connection actually I solder 2 places.
edit- the green wire in the pic is in the correct location
Last edited by ...Roger...; May 27, 2009 at 11:49 PM.
Drifting
Joined: Aug 2005
Posts: 1,430
Likes: 8
From: Hamilton NJ
IMO that overheating is from a bad connection on the unused spade next to the green wire spade-the unused spade is the feed for the rheostat which itself gets its feed from the brown wire spade.
I now on brand new switches solder that bad connection actually I solder 2 places.
edit- the green wire in the pic is in the correct location
I now on brand new switches solder that bad connection actually I solder 2 places.
edit- the green wire in the pic is in the correct location
Can you elaborate on what you are soldering? Any pictures or detailed directions? The overheating on these switches gives me the *******
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
DW thanks for the catch...you're absolutley right. I corrected the post and recommend moving the green wire to the open slot on the left to bypass the rheostat.
Can you elaborate on what you are soldering? Any pictures or detailed directions? The overheating on these switches gives me the *******
Can you elaborate on what you are soldering? Any pictures or detailed directions? The overheating on these switches gives me the *******
