Gauge cluster circuit

[Doug78]

I have starting taking apart my vette for interior restoration. One of the 'little' things that didn't work was the interior lights. Courtesy lamps, gauges, shift indicator - nothing. Only the 'Fasten Seatbelt', 'Gen' and hi-beam ind. work. Today I took apart the entire center console and removed the gauge cluster. When I apply 12 vdc to the bulbs I can only get 2 of the lights or the other 3 lights but not all 5! I traced out the circuit and found that while all 5 bulbs have one lead in common (orange line, don't know if its supply or ground). The other side of the circuit connects 3 together and 2 together (green line). The link at the bottom is to a photo that traced over in paint. What connects the 'green' circuits to each other so that all of the lights come on?


Gauge circuit

 

[Yoda]

Nice Photo and detail

Doug,
The green circuit is the ground (return) the orange is the "Hot" energized leg. If you notice all your light sockets are plastic. The green is returned through the ground of the car. There is a point where everything from the cluster is tied to ground for the return to the battery's Negative side.

I haven't looked at my shop manual, but if you need more information let me know and I'll take a look, the 79 and the 81 are almost identical.

BudD

 

[78SilvAnniv]

I may be wrong...

But I thought if the interior lights didn't work it was a bad headlight switch?
Sil

 

[Yoda]

hmmmmmmm

The attached photo showed the cluster section. I was addressing them. ooops

Grounds are the most common problem with lights.. BAD GROUNDS, the second most common is poor connections in the light sockets, then shorted power leg in the circuit, then switches. Of course any of these can be the problem at any time

Do the simple things first, then move on to the harder stuff.. I've seen were WRONG light bulbs were used, and would not work. 1157 bulbs are different contact points from say an 1154.

Hope this helps Heidi. Thanks for pointing this out.

BudD

 

[Doug78]

Rare81,

F B1
G Sb
B2 B3
B4 B5

If we look at the cluster from the back the bulbs are arranged as above. 'F' (low fuel) is not installed. B1, B3, Sb (seatbelt) share the ground that connects to the harness. B2, B4, B5 are on a separate ground circuit that is also common to the voltmeter but it does not lead to the harness. There is no connection point that I can see for that portion of the circuit. I have not traced back the harness to see why the 12 vdc doesn't get there but the ground must be good because the seatbelt light comes on.:confused

 

[Doug78]

The bulbs didn't retain their spacing but maybe you'll still get the idea.

 

[Yoda]

Doug,
Here is a copy from my 81 Shop manual (GM)

This is one of two,, I'll do the other on another post, both as attachements. I read a little before copying these and they state: "The instrument Panel Ground is located on the Left Hinge Pilliar Above Courtsey Light" It also shows the ground wire as BLACK, from the photo in your attachment, it looks like the green wire is ground ??

BudD

 

[Doug78]

Aaahh!! Its too small. I can't make out anything on the two diagrams. Could you scan them at a higher resolution and email them to me? My email is dsedlow@ihpc.net. The photo of the circuit that I have I made myself using my digital camera and PaintShop Pro. I used green, orange, yellow, etc not to match the wire colors but because they would be more visible on the illustration.

 

[Yoda]

Doug,
Did you get the bigger wiring diagrams. I sent them via your PM?

How's it going? Fun isn't it .. "You just gotta :love 'em

I just got my directional turn signals working :J :J They went out somewhere after Columbia Missouri on the way home from Bowling Green. Found a shorted wire down in the bowels of the steering column.

BudD

 

[Doug78]

The schematics I've received from you folks confirmed what I knew, the ground of the two lamp circuits must connect, but the question is where? The harness that plugs into the cluster provides 12 vdc and ground on the top two pins. The 12vdc is uninteruped to all 5 lamps. The ground is not, the top, middle right lamp (from the back) and seltbelt lamp are in the ground path from the harness. The other three lamps have a common ground path to the voltmeter but that foil run does not connect to the harness. Is there a jumper that's missing? Another wire perhaps? The assembly manual only shows the one harness connecting to the cluster. None of the foil runs are grounded to the gauge chassis. Nor was the chassis separately grounded to the car. All of the gauges/idiot lights work. The problem with no interior lights working is probably the dimmer switch or a fuse but once that is fixed I want all of the cluster lamps to work.

 

[redmist]

Grounded

I got so frustrated tracking down all the little electrical gremlins I ran a #10 ground wire from the frame (which was already seperately grounded to the same point from the engine and ran that wire under the shifter console. I then grounded the guages, radio, lights etc all to this point. Guess what..all the gremlins went away. Nice non-flickering lights, steady guages, great reception.

 

[Doug78]

Once I figure this out I'll write a book about the How & Why and then retire.