Dash lights don't work - HELP!

[jft69z]

1 hour ago, 70SS396 said:

Thanks for your concern Rob but I didn't fall. Hope I don't anytime soon.

Best, Paul valle/ 70SS396 

 

He's talking about Paul Bell, another member of ours.

[70SS396]

1 hour ago, jft69z said:

He's talking about Paul Bell, another member of ours.

Oh, I didn't realize he was talking to me. Thanks 

[Rob Peters]

20 hours ago, 70SS396 said:

Thanks for your concern Rob but I didn't fall. Hope I don't anytime soon. 

 

I was responding to Paul Bell regarding to his elbow injury due to a fall.

On 2/24/2025 at 10:01 PM, Paul Bell said:

Hello folks, sorry I've been absent, I had a very bad falling accident and really screwed up my elbow requiring surgery.:

The above post is the one o was responding to.

rob

[Jim Bowtie]

Great topic! I will be there again with my 70 and have been there with my 84 El Camino also…I have some gauge lights (one idiot light to the right works) so I am pretty sure it is the circuit board. The rheostat is clunky for sure also. Might just have to see if the 84 oem I removed is the same..

Edited February 27 by Jim Bowtie

[B-Man]

Ok, I'm back at this and am making another attempt to get my dash lights working.

I noticed that unlike the photo that @stangeba has earlier in this post, I have a ground wire with a large copper washer on it that gets sandwiched between the face of the headlight switch and the portion of the gauge cluster can that th headlight switch and GEN light are in.

I ran a ground direct to the screws on the top of the can that are integral to the grounding circuit of the circuit board. The lights that do work (behind the AC) do get brighter 

This one has me stumped. I might just drive by candle light!

[Paul Bell]

Brendan, the only purpose the ground ring serves is to provide a ground path for the courtesy/interior lights. It won't affect the cluster bulbs.

Using a test light bulb (not a volt meter), one side grounded, do you have power to light the bulb when you probe the two terminals in the headlight socket with the red and orange wires?

They should both have good power to light the test bulb even with the key off.

See my post above from 2/24 for the diagram.

[B-Man]

@Paul Bell, thanks for clarifying the function of that large copper washer. I still don't understand why I wouldn't have a ground wire like the one pictured. 

I just finished wrestling the switch and plug back in. So can't run the test you suggest. But certainly will if I get a chance to. Thank you for that. 

Some more forensics though ... I do in fact have dash lights (and probably power to those 2 wires you suggest). They are just (a) very dim and (b) not all working. This is definitely pointing to the circuit board, which I have a new one of thanks to one of the most awesome forum members!!

I put in some of the new bulbs / sockets that I have from the forum member. The bulbs that weren't working still aren't working. Again, probably pointing to the circuit board 

As suggested above, I'm going to go ahead and run a new, permanent ground to one of the screws that ground the circuit board to the gauge can. It can't hurt and does seem to help.

I also noticed that if I turn the headlight knob to full bright, just to the point that it's about to click over and turn on the dome light, it gets rid of a bit of flicker - in the actual LED headlights - I was seeing as well as being max brightness (not very bright). And I was swapping out some of the gauge bulbs I noticed that settled out the flicker too.

So ... Circuit board. I absolutely have to drop the dash and get at the gauge cluster to fully solve this problem with the new circuit board. And LED bulbs while I'm at it of course.

Onward and upward!

[70SS396]

There are several ground paths to the lamps on the dash cluster. 

The screws that attach the printed circuit are some of them. The cluster  is grounded by a black grounding conductor that extends from the dash harness to the cluster can which must be a solid connection. 

Another ground issue is where  1 of the ground paths is damaged or broken at the lamp socket nearest the drivers side speaker. The mylar invariably gets bent down to clear the speaker bracket and speaker..

As suggested in a previous post , it's best to run a test jumper from the chassis or emg brake assembly to each  screw that attaches the printed circuit ground to the metal cluster can.

 

 

 

 

[420ponies]

👍 Ditto on the extra ground from the dash cluster. Makes a difference!

[Paul Bell]

OK. Flickering or dim dash lights could be an oxidized/dirty rheostat in the headlight switch, poor grounding, dirty cluster plug, bad flex board or lamp sockets making poor contact with the flex board.

[B-Man]

@Paul Bell, agreed. Or all of those, haha

I'm DEFINITELY going to daisy chain a fresh ground to all of the screws that I can get to. 

The headlight switch is new. And the bulbs / sockets that I have are only slightly used - purchased new by another forum member who then installed a Dakota Dash.

Cluster plug - yeah, I guess it shouldn't hurt to pull it off and clean the contacts. 

The new flex board board might have to wait until next winter. Definitely going to focus on grounds for now

Thanks again for the help

[Paul Bell]

I made this up:

[Paul Bell]

PDF version:

1979-1972 CHEVROLET A-BODY DASH LIGHTS.pdf

[B-Man]

@Paul Bell, thanks for posting that dash lights trouble shooting flowchart.  Nice to have for sure!

I'm basically at the last step having - accidentally, but per above suggestions - figured out that additional grounding and / or wiggling existing grounds improves and isolates the issue I'm having.  Since my 72 doesn't actually have an instrument cluster ground wire (removed by PO?  never had one from the factory??), I definitely need to install one.  It will be daisy chained between the 3 sections of the instrument cluster can.  On top of that, I will replace the flexible circuit board with a new one that I have eventually, plus new LED bulbs.  I'm not sure I will get to that this spring since I'm trying to wrap up projects enough to comfortably drive for the summer.  But next winter DEFINITELY!!!

Thanks again for all of the help guys.  Grounding is the solution

 

[Dtret]

17 hours ago, Paul Bell said:

I made this up:

I like that. I’m not a wiring guy by accident means. And this could make a miserable job a little bit fun. 

[B-Man]

UPDATE: The ground strap seems to have fixed everything!

I just used a standard 12 gauge wire and some ring terminals. I picked up the outermost 2 screws and then one of the wire harness clips holes. That got all 3 sections of the gauge cluster on a common ground. I used one of the ground terminals on the new fuse block I just installed behind the kick panel. And it's grounded to chassis / battery ground.

Now I have (dim) dash lights, and the LED headlights and switchback turn signal bulbs work perfectly. Before I put the ground strap in I could actually turn the headlight switch dimmer down and make the LED headlights high beams turn on - crazy. Amazing what sort of stuff occurs with a bad ground.

So anyway, I'm all set here now. Thanks for the help! I will eventually drop the dash and put the new flexible circuit board in. As well as replace all the bulbs, etc. but for now I'm going to wrap it up and enjoy some summer driving.

[70SS396]

2 hours ago, B-Man said:

UPDATE: The ground strap seems to have fixed everything!

I just used a standard 12 gauge wire and some ring terminals. I picked up the outermost 2 screws and then one of the wire harness clips holes. That got all 3 sections of the gauge cluster on a common ground. I used one of the ground terminals on the new fuse block I just installed behind the kick panel. And it's grounded to chassis / battery ground.

Now I have (dim) dash lights, and the LED headlights and switchback turn signal bulbs work perfectly. Before I put the ground strap in I could actually turn the headlight switch dimmer down and make the LED headlights high beams turn on - crazy. Amazing what sort of stuff occurs with a bad ground.

So anyway, I'm all set here now. Thanks for the help! I will eventually drop the dash and put the new flexible circuit board in. As well as replace all the bulbs, etc. but for now I'm going to wrap it up and enjoy some summer driving.

Patience and perseverance:)

[willie]

8 hours ago, 70SS396 said:

Patience and perseverance:)

Mostly the second P..   Well said Paul!!!

[B-Man]

@Tonka Man, you're the OP on this thread.  Have you installed a secondary ground strap between the 3 gauge housing sections and a chassis / battery ground?

[Tonka Man]

So my original post was about dash lights not working on my green rescue Monte.  Well, dummy me!  I thought it was maybe a burnt out fuse or a bad circuit board.  Welllllllllllllllllllllllllllllllllllll

I was driving it last night (with no dash lights) and I thought I would turn on the dome light to see the speedometer and VIOLA!  My dash lights all came on!  The switch was rotated to the lowest dim setting.

What an idiot!  Why didn't I think of checking that?  Has it been so long that I've forgotten how to operate the lights on these cars.

Very nice surprise!

[Dtret]

7 minutes ago, Tonka Man said:

So my original post was about dash lights not working on my green rescue Monte.  Well, dummy me!  I thought it was maybe a burnt out fuse or a bad circuit board.  Welllllllllllllllllllllllllllllllllllll

I was driving it last night (with no dash lights) and I thought I would turn on the dome light to see the speedometer and VIOLA!  My dash lights all came on!  The switch was rotated to the lowest dim setting.

What an idiot!  Why didn't I think of checking that?  Has it been so long that I've forgotten how to operate the lights on these cars.

Very nice surprise!

The important thing to remember here is that you figured it out and now it’s fixed. Yep that’s what I read. 😂

[Paul Bell]

No worries Tonka Man, I'll walk into another room and forget what I went into it for.

Glad the lights work, it's almost a small miracle on these 50+ year old cars.

[willie]

56 minutes ago, Tonka Man said:

So my original post was about dash lights not working on my green rescue Monte.  Well, dummy me!  I thought it was maybe a burnt out fuse or a bad circuit board.  Welllllllllllllllllllllllllllllllllllll

I was driving it last night (with no dash lights) and I thought I would turn on the dome light to see the speedometer and VIOLA!  My dash lights all came on!  The switch was rotated to the lowest dim setting.

What an idiot!  Why didn't I think of checking that?  Has it been so long that I've forgotten how to operate the lights on these cars.

Very nice surprise!

Wish i had a V8!!!!

48 minutes ago, Dtret said:

The important thing to remember here is that you figured it out and now it’s fixed. Yep that’s what I read. 😂

I agree totally!!!!!

31 minutes ago, Paul Bell said:

No worries Tonka Man, I'll walk into another room and forget what I went into it for.

Glad the lights work, it's almost a small miracle on these 50+ year old cars.

What did you do when you realized you forgot???   I stand there for a half a min, and then walk back to where i was and then i remember what i needed and walk back to get it!!!  Then there was the time i forgot again and laughed at myself for a few min and i would say "wish i had a V8" LOL

[Marks71]

1 hour ago, Tonka Man said:

So my original post was about dash lights not working on my green rescue Monte.  Well, dummy me!  I thought it was maybe a burnt out fuse or a bad circuit board.  Welllllllllllllllllllllllllllllllllllll

I was driving it last night (with no dash lights) and I thought I would turn on the dome light to see the speedometer and VIOLA!  My dash lights all came on!  The switch was rotated to the lowest dim setting.

What an idiot!  Why didn't I think of checking that?  Has it been so long that I've forgotten how to operate the lights on these cars.

Very nice surprise!

That was too funny Nathan, it’s nice to know this type of thing just doesn’t happen to me. Thanks for sharing. Now it’s my turn. 
After selling our house to purchase some land to build our current home and shop, we rented a smaller house and used the garage for storage. This meant storing my 69 Z/28 for about 7 years in a friends garage. After finishing our home I had it brought back on a flatbed. Before trying to start it, I wanted to turn it over by hand. I pulled the plugs and tried a 1/2” breaker bar on the balancer pulley. Should be easy to turn but it wasn’t budging and I certainly wasn’t going to really lean on it. Now I’m starting to get that pit in my stomach. I pulled the starter and tried tuning the flywheel with a large screwdriver. Again, not moving and I wasn’t going to force it. Now that pit is turning into a big knot. So as I’m driving down my driveway on the way to the auto parts store to see if there some kind of penetrant I can spray in the cylinders to break the motor free, it hit me. I stopped and said out loud, “Mark, you’re an idiot, it’s a 4 speed and you never took it out of gear”. The knot in my stomach was instantly gone and after priming the oil pump I had  it running within about an hour. Turned out to be a great day. 

[DragCat]

Some more examples of "Ask me how I know" 🤣