Gauge lights - Forums - Official C3 Vette Registry

SPONSOR AD

Support our Vendors! | Advertise Here

Topic: Gauge lights

in Forum: C3 Electrical

Already a Member?
Login
Not yet a Member?
Register for Free!

Gauge lights (1/19)
9/24/05 5:15pm

74-454

Lifetime Member
Send Private Message

Canada

Vette(s):
Coupe 74 - 454 Drive it like you stole it!

Joined: 8/6/2004
Posts: 533

It has been talked about a few times, but I didn't find the answer I was looking for through the forums.

Problem : lights out on all lights behing the gauges (only the single gray wires; not the "head light" and "the_other_one_next_to_it"; which are dbl wires).

Background info : I replaced the original radio with a Corvette Kenwood unit (which works fine). I used the original radio wires (black and yellow) as well as the lighter for the secondary power (orange) required by newer radios. The gray wire that used to be connected to the old radio is exposed (not connected to anything), but "protected" with a piece of electric tape.

The gauge lights won't come up anymore. Everything else works. These gauge lights (as far as I know) goes to a 5a fuse (that I replaced with a new one) and from there, goes to the light switch.

The current reading at the gray wires (when I remove the bulb) is 0 volts. I did not take a reading at the fuse. (not exactly sure how; where do you connect the ground of the reader and where do you test the fuse itself vs the fuse box??).

I replaced the headlight switch with the same results. All other switch function works well; dim lights, headlights and dash light indicating "head lights" in the cluster. Everything BUT all the single gray wires (I think it's 6 of them, including the one within the transmission console and the one for the old radio.

Any clue ?

I know I have to take a reading at the fuse, fuse box and the switch; just not sure exactly how and what to expect.

I "might" have pinched a wire trying to put the new radio in (You have no idea how much swearing was involved in this one...). By feeling them it all looks okay, but I know it wouldn't take a big cut to create problems. Is there a way to verify this other than "feeling it"?

Our Sponsors help support C3VR

Gauge lights (2/19)
9/24/05 5:20pm

kstyer

Lifetime Member
Moderator
Send Private Message

CUYAHOGA FALLS, OH - USA

Vette(s):
1975 C3 Red, T-Tops, Black Interior. All I need is time and money! Getting there!

Joined: 12/2/2003
Posts: 6424

The gauge lights or insturment panel lights, are fed from the parking light circuit. Be sure the park lights are on first. They have a seperate fuse.

Gauge lights (3/19)
9/24/05 6:27pm

Bob Griffiths

Lifetime Member
Send Private Message

Frederick, MD - USA

Vette(s):
Frederick County Corvette Club (Maryland) Tan 64 365 Hp Conv 4 sp Red 72 4 sp Conv ..running a '68 327 Blue 76 Coupe L 48 4 sp White 79 Coupe L 82 auto Silver 98 Conv, 6 sp 35th Anniv '88 vette

Joined: 2/20/2003
Posts: 548

Ken....
I really do not understand whay you mean make sure the parking lights are on also...

I lost the dash lights on my 72 in April or May...and added it to the list
of things to "fix" this winter... All I have done this summer is to check the fuses...parking lights, Headights,directionals etc work fine as do the other interior lights... Purchased a laminated wiring diagram at Carlisle
and a dash switch under the asumption that was my problem..

Bob G.

______________

Bob
64,72 & 98 Corvette Ragtops
76 & 79 & qa 88 ANC Corvette Coupes

Click on any image for larger view!

Gauge lights (4/19)
9/24/05 6:37pm

Adams' Apple

Lifetime Member
Moderator
Send Private Message

Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 20201

Stephane, to check the voltage at the fuse, the park lights must be on(as Ken says), then ground your test light/volt meter to a known good ground. Any metal panel under the dash should work for this. Then test both ends of the fuses. It should light up on both ends. If it lights on one end, but not the other, the fuse is bad.
Are the lights for the speedo/tach still working?

Just looking at a fuse doesn't always give a good indication of its integrity. Use an ohm-meter to check fuses, with the fuse out of the car.

If the fuse is good on both ends, and you have no panel lights, check to make sure they're all plugged in really well, and the panel has a good ground, still.
I'm going to check some stuff on the wiring diag., and I'll get back with some other info. 'Till then, use a flashlight!

I'm Baaaaaack!

Here's what the wiring diag. shows, as far as instrument panel lighting.
All of the panel lights are powered on the grey wires. The grey wires come from the fuse box, off of a 4amp fuse labled "Inst. Lmps". That fuse is fed from the headlight switch on a dark green wire from the switch, to the "Inst. Lmps" fuse, and then on to the lamps themselves. This is why the lights(parking lamps) need to be on for the inst. lamps to work. The fuse will not be "hot" if the parking lights are not on.
The grey wire you left off of the old radio is the radio light wire. It should not be a problem to leave it disconnected, as long as it is insulated.
It appears that there are two "splices" for all of the inst. lmps. One of them feeds the gauge panel, and the other goes to the speedo/tach panel. If it was a fuse/switch related problem, NONE of the lamps would work. If the speedo/tach lights work, then you have a loose connection at the gauge panel, somewhere.
I hope this helps narrow down the search!

Adams' Apple38619.7962268519

______________

Joel Adams
C3VR Lifetime Member #56
My Link

(click for Texas-sized view!) NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

Gauge lights (5/19)
9/24/05 10:36pm

74-454

Lifetime Member
Send Private Message

Canada

Vette(s):
Coupe 74 - 454 Drive it like you stole it!

Joined: 8/6/2004
Posts: 533

Wow, I need to get myself this wiring diagram. I have seen it on websites here and there, but now... I'm getting one!

It's starting to make sense now.

I didn't think it was usefull info, but to be able to pull the cluster out, I had to move the whole middle too, which required me to put the transmission out of park (with the emergency brake on of course).

Not sure about the speedo/tach, but I think they were off as well. Which means it could be another fuse.

About the headlight switch, the prongs are numbered, but I couldn't find any description of what they mean. I think there was about 7 or 8 of them. (And btw, when buying a replacement headlight switch at a local car parts, make sure there's the vacuum plugs on them, mine didn't; have to return it now...)

Allright, I have more than enough to play with tomorrow. I'll let you know what I find out. Thanks for all the info and research time, I really appreciate.

Update (didn't mention before):

My fuse box says 5a, but the book says 4a. I tried a 4, a 5 and 7.5; same result.

I'll rather stick with 5 because the box says so, but it's confusing. (Don't worry, the 7.5 is out; it was just a test

)

74-45438619.9470601852

Gauge lights (6/19)
9/25/05 7:24am

Eddie 70
Former Member
Send Private Message

Kingston, TN - USA

Vette(s):
1970 Vert Both Tops Kiesler 5 Speed Steeroids Rack and Pinion Stayfast Convertible Top

Joined: 7/5/2003
Posts: 900

No one has mentioned, or maybe I missed it, checking to make sure the cluster is grounded. It has to have a ground to get the lights to work. Check to make sure the ground wire is connected good.

Gauge lights (7/19)
9/29/05 10:47pm

74-454

Lifetime Member
Send Private Message

Canada

Vette(s):
Coupe 74 - 454 Drive it like you stole it!

Joined: 8/6/2004
Posts: 533

Still confused....

Tonight, I checked the fuse (with an ohm meter)... and ... good fuse! (is there really a difference between AGA and AGC ???).

The speedo/tack have light, but still not at the cluster.

Without the fuse in the box (5 amps in my case for a 74 instead of 4 amps), there was no current at all (with the key and light switch on).

Is the 74 supposed to have a circuit breaker (like the Chilton & Haynes books says, cause I could not locate it) ?

I tried to pull the fuse box out, (two screws), but could not pull it out enough, something behind the firewall (in a box) is holding it ... I think).

2 questions :

- Is the console ground we are talking about under the transmission console ?

- what do you guys mean by "park lights" ?

Thanks!

Gauge lights (8/19)
9/30/05 1:41pm

Redwingvette

Lifetime Member
Send Private Message

Waterford, MI - USA

Vette(s):
1973 Red coupe

Joined: 9/13/2002
Posts: 1747

The original radio black wire was also the wire that grounded the gage cluster. Once you took the radio out you will need to run a ground the the cluster and connect it to a good ground. I had the same issue when the Po replaced the radio and didn't ground the cluster. I attached a ground wire to the back of the cluster and attached to the metal peice under the instrument panel. Also me gages did not work right because until I did that. The temp gage would change everytuime I turned on the lights because it was back feeding through the lights.

______________

Brian - NCM Lifetime Member

73 coupe L48, Flat-top pistons, Performer RPM Heads, Crane Cam and roller rockers, Holley 650 vac sec. Performer intake,
3.55 gear BTO 200-4R trans,
Leather seats, Seatbelt Plus 3point seatbelts, Pioneer CD player
Magnaflow Exhuast System

Dewitt radiator and dual electric fans

Borgeson Steering box

Gauge lights (9/19)
9/30/05 7:02pm

Adams' Apple

[QUOTE=74-454] ..........

Is the 74 supposed to have a circuit breaker (like the Chilton & Haynes books says, cause I could not locate it) ?

�

I tried to pull the fuse box out, (two screws), but could not pull it out enough, something behind the firewall (in a box) is holding it ... I think).

.......

- what do you guys mean by "park lights" ?

�

Thanks!

[/QUOTE]

The "circuit breaker" is actually part of the headlight switch. This is not going to be your problem, tho.

The fuse box is held in by a bolt thru it from the engine side of the firewall. Also not going to be your problem

"Park lights" is what some people call 'running lights'. If you pull the headlight switch out to the first position, you have only the "park/running" lights on. The second position(all the way out) turns on the headlights, also.

You have a ground problem with your center gauge cluster, and that is why the lights for the gauges are not working, but the tach/speedo lights are. With the tach/speedo lights working, it means the light switch is good, as well as the fuse(s) for the inst. lights.
If you have the wiring diagram for your car, you should be able to find where the ground is for the cluster, and trace it from there. I'll look at my diagrams and see if I can give any more help with that. ("I'll be bach!"

)

Brian(redwingvette) is correct!! The ground for the cluster IS the same as the one for the radio. If you still have the connector for the orig. radio, it will have 3 wires. Grey, black, and yellow. The grey wire is for the light in the radio: the yellow is for power: the black is ground. It goes to a "console ground". You should have a connector on the back of the cluster with two black wires comming from it. These wires splice into the black wire from the radio, and then it goes to ground. I think you can just do what Brain said, and run a separate wire from a good grounded spot to the black wires, and be in business, if you can't locate the original ground spot. It will be under the center console, and the diagram shows two black wires connected at that spot. It is this terminal that is causing you to be "in the dark"!

Hope this makes some kind of sense!

btw....this same ground is used for the cluster ground, which explains why Brian's gauges didn't work correctly until he grounded the cluster.

Adams' Apple38625.8063194444

______________

Gauge lights (10/19)
9/30/05 8:24pm

74-454

Lifetime Member
Send Private Message

Canada

Vette(s):
Coupe 74 - 454 Drive it like you stole it!

Joined: 8/6/2004
Posts: 533

WOW, thanks for this research. I have many wiring diagrams from books, but they always seems to "skip" the cluster and most of the grounds. 10 minutes ago, I ordered a full size (and color) wiring diagram from http://www.classiccarwiring.com/ (sorry for the free publicity).

About an hour ago, I tried what Brian suggested, but I didn't do it from the 2 black wires; I simply hooked one side (of a 14 gauge wire) under one of the console retaining screw down to a metal plate under transmission console. Now... obviously, it didn't work!

I didn't know about these 2 black wires. Will try tomorrow.

Funny, I was re-reading the thread and realized that Eddie was right on the money in the first place, but I didn't understand "grounding the cluster"; I figured that if I didn't touch anything else but the radio, the cluster had nothing to do with it.

I call the "park lights" the "dim lights"

; but what the heck do I know, english is not my mother tongue and car lingo is new as well. You guys should hear the words I make up sometimes trying to explain what I'm looking for. Kudo to all the local parts store clerks who have the patience to deal with me trying to decypher "that little round thing that makes 'click' when you push/twist on it..."

Thanks again for all the help.

Gauge lights (11/19)
9/30/05 9:27pm

Adams' Apple

Stephane, we're all glad to help, I'm sure!
I would suggest you locate & purchase a factory "Service Manual" for your '74. This is where I get my wiring diagrams, and they are the most complete you'll find. You can find the shop manuals at swap meets for around $40, usually. I see them from time to time on e-bay, but some of them are way overpriced. These manuals come in handy for a lot of stuff, including specs for just about everything on the vehicle, remove/replace instructions, and repair info, as well as troubleshooting charts.

______________

Gauge lights (12/19)
10/3/05 10:32am

74-454

Lifetime Member
Send Private Message

Canada

Vette(s):
Coupe 74 - 454 Drive it like you stole it!

Joined: 8/6/2004
Posts: 533

I have the service manual, but couldn't make much sense out of the wiring diagram. I traced it with a color pen and "almost" understood what you guy's pointed out concerning the console ground.

I tried it, but it didn't work; same problem, with the temperature gauge showing a little over 300 (engine cold). I might have not used a good ground and I only had a few minutes.

I'll go back to the garage sometimes this week and try again with another ground. I used the one on the bottom left (driver side) of the console where there was already another ground terminating over there. I will try again with a different one.

Gauge lights (13/19)
10/3/05 6:13pm

Adams' Apple

Try running a wire all the way to the ground term. on the battery, just to see if it(lights/gauges) works. Then try to locate a good spot to ground the panel.

If the ground to the batt. still doesn't get the lights to function, then we've got something else going on.

______________

Gauge lights (14/19)
10/3/05 8:46pm

kstyer

Or connect a test light or volt meter to a good ground, and touch the other lead to the light cluster ground, the metal brackets. If the light lights or the meter reads a voltage, you have a bad ground.

Gauge lights (15/19)
10/15/05 6:23pm

74-454

Lifetime Member
Send Private Message

Canada

Vette(s):
Coupe 74 - 454 Drive it like you stole it!

Joined: 8/6/2004
Posts: 533

I found the problem : ME.

Ken mentioned it on the last post, but I didn't get it until I started looking at my wiring diagram this afternoon. I previously overlooked that the ground is right there; at the bulb.

It took me a good 3 minutes of staring in space trying to figure out how it can have his own ground when there no second wire coming out of there.... UNTIL I notice that the light socket bracket is metal!

Not sure if I mentioned before, but the whole time, all the bulbs were disconnected from the cluster; just hanging.

This is what I've been looking at for the past 4 weeks. All this just to add a radio and speakers. The "non" problem started when I tested everything before putting it back together and realized the cluster bulbs were not working (or at least is what I thought).

I can now put it back together and start enjoying the Florida autumn and winter (best time for driving the Vette).

Here's the funny part : one of the light bulb behing the speedometer of my Explorer went out yesterday.

(The link is now fixed)

74-45438640.7894791667

Gauge lights (16/19)
10/15/05 6:50pm

Adams' Apple

I guess we all assumed it was all put together, and the lights didn't work. Never thought about them not being connected to the panel!

Glad ya got if figgered out, tho!

btw......"What", above, looks like "The page cannot be displayed"!!

______________

Gauge lights (17/19)
10/15/05 7:01pm

74-454

Lifetime Member
Send Private Message

Canada

Vette(s):
Coupe 74 - 454 Drive it like you stole it!

Joined: 8/6/2004
Posts: 533

I fixed the original link.

It is https://www.c3vr.com/member_uploads/6401_6500/6425/P9300887.J PG

Gauge lights (18/19)
10/15/05 7:11pm

kstyer

Glad you got it. Even thought it was self imposed. But that's how you learn. We did guess they were plugged into the housing.

And believe it or not, your picture actually looks tidy and in order compared to the inside of mine at the moment.

kstyer38640.8002314815

Gauge lights (19/19)
10/15/05 7:15pm

Adams' Apple

That's it!??? Jeeeez......looks like a simple 5 min. job to me!

All kiddin aside, glad you got 'er fixed! I hate gettin' into a "simple" project that winds up takin' weeks!

Congrats on the progress!

______________

Our Sponsors help support C3VR