Instrument panel bulb layout (Page 1/2)
rice.1 JUN 11, 11:52 PM
Does anyone have a diagram showing which bulbs light up what on the instrument panel? I ordered the brighter bulbs from Rodney dickman and it came with one, but just showed which bulbs went where to change out. It was for the 85 mph panel for an 85. I misplaced the diagram anyway.

Would anyone have one for the 85 mph as well as the 120 mph? I have a few not lighting up (right turn signal indicator for instance on my 85 mph)?

Also, I think I saw most of the bulbs were plug and twist type 194? I may be wrong on that.


1987 Fiero GT
1985 Fiero 2M4

theogre JUN 12, 03:33 AM
bright standard bulbs = more heat... Fact is 194 bulb can cook the socket and worse over time. Most dash lights are not on long enough to cook the sockets. Light for gauges Shouldn't be on at full power. If dimmer is "full power" and light are dim then adding hotter bulbs is wrong answer.

Even if all bulbs are good, Dim bulb can be a number of things.
Most problems are here...
See my Cave, Dash Dimmer

Multiple bulbs out at same time could be:
plug(s) on back of dash have problems
Socket(s) are bad
"circuit board" is just not making contact at either/both points. Wiggle bulb socket(s) often helps. Or getting new sockets.

Example: I had seat belt light out but the socket was just loose. Rotate socket a bit like you going to remove it can make socket to get a good contact w/ the "board." Metal ears of socket will "crush" the plastic board and won't make good connection.

All use 6 bulbs for gauge lighting. Note that All or Most of FSM and others are Wrong. (A Data Error was never fixed.)
2 behind Speedo (L & N below)
2 behind Tach (A & B below)
2 behind Fuel and Temp (Not listed in FSM.)
View from Back of Dash

B&W Image from 88 FSM

Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

[This message has been edited by theogre (edited 07-09-2023).]

rice.1 JUN 12, 01:42 PM
Thank you, Ogre.

I'm not desiring brighter bulbs at the moment. I just didn't know if 194 was the correct type or the brighter type. I just have a couple that went out on my. I'll try rotating them a bit and seeing if that corrects the issue.

Thanks for the information.

theogre JUN 14, 02:31 AM
I have a spare backlight dash took apart for other work so took a picture showing how the lights are used inside the Gauge Cluster.

C Upshift
D RH Turn
E Battery
F Seat Belt
G Check Engine (MIL)
H Ajar
I LH Turn
J Temp Warning
K Hi Beam
M Brake

The two wells above A & B light for the tach are often filled w/ sockets and even bulbs but does Nothing.
Funny thing is Wiring Diagram for the cluster shows 6 bulbs but veiw from back above only shows 4. (Most FSM and others have this.)

Rodney saying:
The 85 MPH speedometer dash's have 7 bulbs for gauge illumination.

The 120 MPH speedometer dash's have 6. (There are 4 bulbs in the main gauges and 2 in the extra gauge set above the radio making them 6 bulbs for gauge illumination).

Is wrong. I have no clue how He got his data.
As the picture above shows...
85mph uses 6.
120mph have to use 6 too. (Total 8 w/ aux gauges over the radio.) You can not light the temp & fuel gauges w/o O and P because the "Idiot" light wells prevent this.

Orange paint is OE for 85mph. Back of front metal cover is also painted the same. Is why changing light colors can do very odd things.

If you look carefully at G you might notice the inner side is a bit Tan... The Bulb burned out and cooked the socket etc in the process because MIL light was on full time. Morons even covered the hole to hide ECM screaming for problems. (Very likely because you won't pass inspection w/ MIL on in many states.)

[This message has been edited by theogre (edited 07-09-2023).]

theogre JUN 21, 02:45 AM
Side Note: Most dashes are Dirty making the light dimmer. Lights need the white to give good output to uniformly light the gauges. IOW the white reflect the bulb output and stops or reduce any bright spots as you look at speedo etc. Problem is as you can see above and here... Fiero and most others, assembly isn't sealed. Back shell have/had foam glued inside of it but many are gone allowing more dirt to get inside.

This is picture is halfway thru of the cleanup of my dash. (No retouching other then adding text and resizing for PIP.)

Right half is grey compared to left side, more compared to "idiot" lights. Idiot lights have wells and caskets so they seal light in (You want turn bulb only to light the turn symbol) and means they seal out dirt. The lines around then are where the gasket are. (You can see some of the Black gasket in above post.)

I used window cleaner and soft rag. Is not as bright white as OE but a lot better then the right side. OE white is when the idiot light gasket covers normally. Stronger cleaners might do better but solvents can cause problems. You don't want to eat the plastic.

This was better then expected... Not much loose dirt/glass. I cleaned out many dashes w/ a lot more loose dirt, broken glass, even where mice though was good place to live.

[This message has been edited by theogre (edited 07-09-2023).]

2.5 JUN 21, 08:48 AM

Originally posted by theogre:

Orange paint is OE for 85mph

But not for 120?
theogre JUN 21, 12:27 PM

Originally posted by 2.5:
But not for 120?

Just Not sure. I've never seen 120mph to look close enough or take it apart.
I'm told all 120mph sets are back lite for speedo and tach, maybe fuel and temp too.
Back light color depends on "film" and other parts the light goes thru, Like all idiot lights are white bulbs passing thru plastic cover.

Could be mains are back-lite and fuel and temp is side lite so could still have orange paint.

85mph setup...

Notice the top wells over the tack... doesn't even have hole in the sheet metal.
This is missing a set of gaskets for top of idiot light wells. Either PO remove them or 86 didn't come with. The gaskets is just held in place by metal ears that holds the idiot light film. Gaskets here are thin plastic w/ foam and the foam goes bad over time.

[This message has been edited by theogre (edited 07-09-2023).]

2.5 JUN 21, 02:48 PM
So painting that yellow/orange silver instead, you could use any color LED and have that true color light shine thru.
theogre JUN 21, 06:02 PM
Yes and No... (Ignore light pollution driving in the city. External lights from Street lights etc can hind problems.)
85mph pointers and some gauge markings are orange too, close to same as the paint above, and people have hard time seeing them when lite w/ another color light. Worse when light color is "pure" from say Blue LED.
OE White bulb w/ paint to reflect light isn't a pure monochrome output but a Blue LED is. Orange pointers can go nearly invisible under blue light.

Same problem Arc lights for street lights (often lights are pink or yellow) or Yellow/amber "anti-bug" lights for home... Both are monochrome lights and often do very odd things depending on finish of other items to light. Example: I have Green chairs + "bug light" = chairs can look dark/black.

Also why your eyes and many cameras have problems when Theater lights are set to pure red, green, OR blue... Backgrounds, costumes, etc can be normal in "white" light and turn dark or even another color, sections or whole thing, when viewed under any monochrome lighting setup.

Changing Colors for 120mph is harder to impossible when you don't change gauge background etc.
Example: Somewhere in archives is how you can fix back-lite pointers to light w/ another color. Big issue is First you must carefully remove the pointer's paint. You can wreck the pointer very easy.

[This message has been edited by theogre (edited 06-21-2016).]

theogre JUN 21, 08:27 PM
double post

[This message has been edited by theogre (edited 06-21-2016).]