Instrument Ground?

[bguild]

Okay I am starting to go through my wiring mainly trying to fix my gas gauge. I am trying to figure out where my ground on my instrument cluster goes??? I think I might have some ground issue and I bought the wiring diagram but mine shows its going into the main underdash harness and I am not sure where its actually ground at.

my gas guage does not work and i am checked the wiring. The weird thing is that the gas gauge wil bounce a little when i turn on my turn signals or hazards. Weird I know.. Also alot of my lights are very dim and dont work right in the cluster. Any ideas? I plan to really dig into this weekend as well as hook up my stereo.

[bguild]

Also I noticed there are two types of clusters.. One with idiot lighst and one with guages. Could it be that the Previous owner had the idiot light dash and put the gauge dash in.. Maybe i have the wrong harness? Nothing really works.. My lighst etc dont work. My turn signals do work but they seem very dim. The rest does not work. My oil guage and my speedo work but you know those are mechanical and not electrical. Any help would be appreciated.. I checked fuses already and cleaned the connectors on the cluster harness..

[bguild]

no body????

[71meangreenc10]

The last time I checked, there was a black wire that connected near the steering column area. It clipped into the metal for a ground.


Smitty

[motornut]

i'd walk around check all the light grounds to start

[VA72C10]

It is possible the harness is the wrong. I know there is an faq on how to make a non gauge harness work with gauges...

[VetteVet]

Just make a ground wire by crimping an eyelet on each end of a wire long enough to reach from the cluster to a good ground in the cab. You can put the cluster end of the wire under one of the screws that hold the cluster back on.

Like the one in this picture on the top left.



The harness plug in is pinned differently for the cluster gauge panel and the idiot light panel. The differences are minor and easy to change. Here is the idiot light connector.



Here is the one for the gauges.



A picture of the plug.

[bguild]

^^^^^^^ Awesome.... Thanks so much.. I will dig into it this weekend.. I also noticed my circuit board is somewhat messed up so I might go buy a new one of those this weekend to see if that helps.


Also where should my light grounds be.. All my lights work except for my dash lights.

[bguild]

Also the other light that works is the brake light on the gas guage but only comes on when I am starting the truck. HHMMMM. Hopefully I can figure it all out this weekend.

[VetteVet]

so you have this dash?


Here is the circuit for the gauge dash and if you have a bad circuit board that could be your whole issue. The lights get their grounds off the circuit board. See pin 7 on the wire map on the left of the diagram. The orange colored wires to each light are their grounds.



Look at the circuit below the fuel gauge and you can see the brake light. The purple line is the gauge power feed line and the green line is the switch line from the ignition switch that turns it on when the key is in the start position. This wire is originated from the brake proportional valve at the master cylinder and turns on the brake light in the dash when it is grounded either by a difference of pressure in the valve or by grounding through the key switch which is done on starting to test the bulb. If you pull the light brown wire off and ground it somewhere, with the key on, the bulb should light. Yours is working as it should.
The temp light is deleted in the gauge dash but would be there in the idiot light dash as would an alternator charge light. Note that all these lines are copper strip lines in the circuit board. See the pic. below.

[bguild]

Yes that is cluster i have. This is great information. I cant wait to find some time to dig into this weekend.. I hope i can get it all working and also have a gas guage. Thanks so much for the help. I will update the thread when I get some progress.

[bguild]

okay guys I am tearing into this electrical today.. its already hot heat index is suppose to be 110.. anyway I have the gauge out and looked at the back. My circuit board was a little trash so I replaced that one with a spare I had laying around. I also adding the ground on the dash. I plugged it all back in and nothing same thing that I had. I do have one light that is connected into the wire harness see picture below.


It looks as if the wiring that comes into is not connected to anything. This could be my whole issue if this is where the lights get their power. Let me know your thoughts. also what plug does this connect into the light hole at the top left of the above diagram?

My gas guage had no difference.. and sorry my pictures are turned.
Here is one when with the truck not turned on.

here is one with the brown gas sending unit wire unplugged.

here is one with the brown cable stuck on a ground in the cable.


to me it looks like my gas guage is working as it should but not a gas guage genious so I am reaching out to you guys. What do you think? Should i just go buy a new sending unit?

[bguild]

also that bulb is coming out of my steering column..

[VA72C10]

the bulb going into the steering column actually is a fiber optic cable that lights the column.

[VA72C10]

have you checked the main harness going into the back of the cluster to see if it is the one that's supposed to work with gauges or dummy lights?

[bguild]

Yes mine has all the right colors in the right pin locations. Hhhhmmm. Any suggestions?
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[bguild]

Okay I think I am going to go buy a sending unit. I still don't have dash lights I am u sure is there a separate ground for lights? All my outside lights work as they should.
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[bguild]

Okay I was checking my fuse panel with my light tester and I can't get anything to light up. I have tried multiple places for the ground. It still won't light up. However my ignition blinker lights on dash work so I know I have power there. Frustrated at this point.
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[bguild]

Well the gas gauge was the sending unit. I bought a new sender and a wire worked right away. Now for the lights I bought all new lights. Maybe they are burnt out. I will update when I get those fixed.
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[VetteVet]

This thread goes through a complete troubleshooting and wiring circuit for the dash lights as well as a description of the dash light wiring circuit.
http://67-72chevytrucks.com/vboard/s...d.php?t=416018

[bguild]

Okay I think this truck is cursed LOL... I got the gas gauge working so I am pleased with that. I also replaced all the lights in the dash but I still cant see any lights. I am going to go drive it around the block tonight to see if they are just so dim I cant see them in the daylight. I also installed my stereo but the reason I think this truck is cursed is that the stereo has a short or something. At first it would power on.. then I wiggled the plug and it power up. I was then all excited plugged in my speakers and nothing. Played with it for awhile and figured out if i jiggle the rear harness plug it will sometimes play the music. I think it has a bad connection. I cant believe this thing. Cant something just work on this thing.. Its being stumborn but if I had been sitting for 6 years I guess I would be grouchy too. (-: Thanks for the help with this stuff. I will slowly get there.

Oh yeah and my temp gauge on teh dash doesnt work either (-:

[danomano]

The light problem could be from the driving lights switch. Some of these can be dimmed to almost off. So it might be off or the light switch (this turns on the head lights) could be bad.

[babylonflyer]

my board is toasted !! does anyone know where i can grab another one??

Vett I searched ur post !! very nice................ in a borat voice !!!

[cdowns]

i like to run a ground wire from the sending unit housing to the body to make sure the tank and sending unit have a good ground

[babylonflyer]

silly me .... lmc trucks $40