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Discussion Starter #1 (Edited by Moderator)
Based on the numerous posts about dash lights not working and too much personal experience w/the issue myself, I figured I would post a quick step by step on how I finally resolved this issue on my Camaro.

Most dash light's not working are related to ground issues. I'm working on a '67 but what I'll run thru will probably work for a '69 too. Follow this process and you should address your ground issues.

1 - Do you have power coming to the circuit board from the harness? When you turn on the lights, the wire going to the circuit for the lights should be live. If it isn't, your issue probably isn't a ground issue but a bad fuse, headlight switch or wiring issue. This needs to be solved first.

2 - Are you sure the cluster is grounded? Take a test light and connect the clip to a 12 volt power source and see if it lights up when the probe touches the cluster. There is a wire that loks light a bent paper clip that goes from the back of the cluster to the middle upper screw that holds on the cluster housing. It is often broken or not making a proper ground. If it doesn't light up, run a dedicated ground from the metal part of the cluster to a good ground. I run a dedicated ground from the back of the cluster housing even with the original wire in place b/c the original wire is a really poor set up to get a good ground.

3 - Are all your bulbs good? You can test them by twisting them out and running a live 12volt wire to one terminal and a ground to the other. Your cluster should still light up if one or more bulbs are dead but won't if they are all gone which is a possibility in a 40 year old car. Also check the bulbs in the screw in holders to make sure they are making a proper connection.

4 - Is the circuit board properly grounded to the housing? This one often the real culprit. You need to remove the cluster from the car and ground it w/a wire. Then take a 12 volt wire and connect it to the various circuits on the printed board. You can tell which one is for the dash lights b/c it goes to each bulb. On a '67 it is on the top left of the board. When you power it you can test the board w/a test light by checking the hot side of the circuit board by each light. You should also check the ground side of the circuit board by connecting the clip side of your test light to a live 12volt circuit.

You may find that one of the ground screws between the board and the cluster isn't making a proper ground. This can usually be fixed by removing the screw, cleaning the circuit and cluster and replacing the screw. The screws that should be ground out are easy to figure out by following the circuit board.

While you're at it, test all the lights and circuits. Just be careful because some of them ground off the harness and not off the cluster. You can see this by following hte circuit board.

Then put it all together and make sure you keep the new ground for the cluster in place when you put the dash back together.

Good luck and enjoy seeing how fast you're going at night again!!

Paul
 

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Looks like a good sticky for the electrical forum. Thanks for sharing Paul.
 

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Discussion Starter #3
I modified an image off the board to detail the workings behind the cluster. I made the positive circuit red and the ground yellow. This should help with steps 3 and 4 of the process in my original post.

Good luck and I hope this helps someone in the future.

 

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I like it.

If you don't mind, I'm gonna add a few things to your original post, and include this in the electrical basics sticky.

I wish I knew photoshop well enough to be able to select the runs and color them like that. Separate colored photos of 67, and 68 tach and non tach PCB's, with all the circuits detaile, would help many.
 

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i have a brown wirer about 5in long by fuse block with conector on it what hooks up to it,also the high beam indicator light i read there is a red lense that the bulb with green wirer hooks to with the ground strap that hooks to cluster,i cant find this red lense in any parts book,there has to be a wirer that hooks to fuel gage,what and where,thank you
 

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Great post. I was having trouble on my 68, gas gauge cluster was dark while speedo cluster was lit, it took the whole thing apart and checked it with an ohm meter and it turns out it was fine. The problem was the connector sockets of the light bulbs were corroded after 40 years. I cleaned em up with some sand paper and swiss files and they worked fine for a few months. But now the whole cluster goes off and on, but now Im 90% sure its the ground wire fix Ive got to do based on this thread. Yay! : )
 

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also if you have the cluster out make sure that the metal connections on the bulb sockets are bent out slightly. after a while they tend to bend inward and do not really make a good contact. You can use your fingernail to pry them out slightly and get a better ground. You should do this to each socket

Brandan-
 

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I have the tic-toc-tach version:

MOD EDIT: Original direct link photo lost when photobucket account was closed. Posted what I think are close to the photo was here from an archive but not sure until owner sends me link to new location of his photos...
Oops, need to add key:

Black = ground
Gray = cluster light power
Brown = tach
Dark Blue = right turn signal
Tan = e-brake/diff. switch
Light Blue = left turn signal
Yellow = low fuel warning
Pink = 12V

I used those colors since those are the wire colors that are in the plug/harness...

Also, the other circuit (not grounded to cluster housing) is actually a power lead trace (pink) going to the sockets with the other side of the light socket going to the associated "switch". In other words, when the e-brake switch grounds, the BRAKE light in the dash is grounded. When the temp. sensor switch in the block (non-gauge cars) is closed and grounded, the light in the dash is grounded. Etc., etc. This works for the Low Fuel Light in the gauges cars, too.
 

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good info. I have a 68 and am trying to get the dash carrier off to get access to the back. do you have to drop the steering column to get the dash carrier off? if so, how do I go about doing it? thx!
 

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It seems to be the only way to do it w/o some force... I just remove the plastic column covers under the dash and pull out the column mounting bolts. DO NOT put much, if any, down force on the column once the bolts are out. This method is really a quick way to do it. It can ruin your rag joint if you put too much force on the column... Support the column if left unbolted. But I recommend putting the bolts right back in.
 

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thx flyingskibiker - are the column mounting bolts the 2 that connect the column to the dash? or the 4 that are on the underside of the column itself? I also had trouble taking the steering wheel off. I took off the nut but the wheel did not budge -do I need a puller?? thx again
 

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Hmmm, I don't remember exactly. Were they nuts? I'm pretty sure it was two big nuts holding the bracket on...

Yes, you need a puller. Pulling on the wheel by hand is a bad idea...
 

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i have a light bulb out on the gas gauge cluster can i replace the bulb without removing the cluster.
 

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Mike you may be able to reach your hand through the back but it is difficult(I can get my hand on the bulb but difficult to turn). It may also be a ground connection that failed and by moving the socket slightly, it may help. Worst case, drop the column and pull out the cluster.



Brandan
 

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Hello,
My issue is when I hit a bump the dash lights go dim and the directional lights come on.
Is that the upper ground wire you all are talking about or something different?

Thanks
Mike
 
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