86 GT 5 speed. I just fixed a no start no crank because of a ground to short at the grounds in the back under the c500 block. I had removed the gauge pod to get to the steering column to replace ignition components as part of the process. Got car running but when I put the gauge pod back on no gauge lights. Everything else works.

I see the check engine come on and off, the e-brake....I flip on lights I get parking lights, rear lights, head lights, turn signals, under dash lights, above head lights, chime and dingy etc..... just no main gauge lights, AC control lights or radio lights?

I read all the posts, the cave etc. but nothing seems to give the answer to this mystery.

I have power to and from the dimmer and the test light will fade down when I dim the switch.I also swapped out another dimmer to test with same result.

Can the dimmer be jumped?

I have power to and from the transistor. I jumped it but still no gauge lights? I thought I should have full bright when jumping the transistor?

I know all the grounds are good because I literally check every single one on the car while resolving the no start no crank.

My printed circuit board is in good shape. No breaks on the visible surface. The legs or tabs in the connector slots are pretty good except the rt side vertical. I had to solder a few of those down but they been working great up to know.

I put a test light on the circuit board when the key was in the #2 position and had power on both sides of the lights that did light up.

The fuses test good as well.

My last resort is to replace the printed circuit board with one I have as a spare but really don't want to go thru all that if I am missing something small.

Any help is greatly appreciated and thank you ahead of time. It is 90 degrees in NC and I have been sweating like a sugared up fat kid at a cake party up under the dash and I am about to lose my sanity.

**UPDATE**

I rechecked the fuses and realized when upside down I checked the wrong fuses.....sorry about that.

The two fuses I understand to be relative are the "gauges" and "instrument LP" ....they show no power?

Not sure how that is when I ave power to the connectors?

read dimmer page carefully again.
Correctly Jumping the transistor is there. Jumping it wrong can/will fry the wheel or transistor.

see diagram near bottom.
inst light fuse only protect the transistor.
dimmer wheel and transistor is after HL switch and on tail light fuse.
Tail light works then HL switch or wheel can causing transistor problems. Brown wire should full volts (12-14v) at the time w/ HL switch is on. If not then likely tail and other lights are out too.

HL switch and tail fuse should have power all the time.

------------------
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

Thanks for the reply!

I removed the transistor then jumped the dark green and brown wire just as it said.....Nothing. I do have power in and out of the transistor plug.

I know the wheel is good because I put the test light in the bottom wire connection and the test light dims as the wheel goes down and goes bright when it goes up.

It is like I have power going in and out where it needs to be but no gauge lights.

I just really hope it is not the flexible circuit board. I do have an extra but it looks like a delicate job.

I do have HL and TL and all other lights inside and out.

It is quite the mystery?

- probe/end to frame ground and + to brown wire is 12+v or test light is full on?
does taillights come on?
if either is no then likely HL switch or its connector is bad.

if brown has power... when you jump the trans then dk green and gray wires should get power when meter/testlight is grounded to frame.

dimmer works w/ factory radios and other lights too. Not just dash lights.

So if I followed your posts, you have power coming to the transistor connector on brown. You have power going out on dark green. But no power shows up on the 5A fuse. I would say that between the transistor socket and the 5A fuse, the green wire is open somewhere.
If you are careful, you could jumper 12V to the side of the 5A fuse that goes to the lights.. and when I say careful, if there is a short to ground, you won't have a fuse.. so just touch it briefly to see if the instrument lamps light up. That would tell us a little more data.
You could also do one more thing. You can put the transistor back in the socket, put your test lamp on the dark green wire leaving the transistor, and the dimmer wheel should vary the brightness of the test lamp.

I just jumped the transistor again (12v all around and with switch and wheel), I then tested the fuse, it was blown. I had not tested it with the trans jumped. So there is an issue after the transistor to the fuse.

I put in a fresh fuse turned on lights heard a beep and fuse was blown.

So no I will be searching out what is blowing the fuse.

quote Originally posted by Scooter_86gt: I just jumped the transistor again (12v all around and with switch and wheel), I then tested the fuse, it was blown. I had not tested it with the trans jumped. So there is an issue after the transistor to the fuse. I put in a fresh fuse turned on lights heard a beep and fuse was blown. So no I will be searching out what is blowing the fuse.

Something is shorted the gray wire to ground.
Examples:
If you pulled the 2 plugs to back of dash, the "board" itself can have shorted "pins" where plugs go into the board.
One bad "bulb" or bulb socket can short out. Bad "Bulb" includes aftermarket LED units too.
Aftermarket radios often have wiring problems caused by bad installers and can short the gray wire.

Also check the fuse block, look at the connections, if they have discoloration, look real careful for cracks.
They should be 'bright and shiny'

I am going to work on the dash/gauge pod over the next couple days.

The only variable that is not as it was before I did the most recent work to resolve the not start no crank is the removal of the dash pod. Plus I know there are some issues with the printed circuit board which are probably worse than I perceive them to be and what is causing the problem. Luckily I have the spare board.

I will post what I find out and hopefully that I fixed it. I will also try to put up some photos.

Also, thanks sardonyx247 for the input on the fuse block, I will check it out too.

[This message has been edited by Scooter_86gt (edited 07-14-2017).]

I have seen where the circuit board has dead spots on the lights, twist a little and they come on.... but not all at once.

**UPDATE**.....Some progress.....a couple questions

Since the gauge pod and printed circuit seemed ok, I decided to take it out of the equation.

I put in a new fuse, left the transistor plugged in, gauge pod off and hit the lights while seeing if I could see any power to the connectors that plug into the back of the pod. No voltage or power to the grey wires......and no blown fuse.

Then I Jumped the transistor, hit the lights, blew the fuse..(without the gauge pod connected)...Not sure what this means? other than it is not the gauge pod?

To me this seems to at the least eliminate the pod and the printed circuit board as the problem. It seems to be an issue before the pod?

I do have an aftermarket radio in the car that has had no problems or caused any for the past couple years. I unhooked the radio checked all the wires all looks good.

QUESTIONS:

1-Is there a way to test the cables that plug into the pod for power to the grey wires etc? ....for voltage, continuity or anything?

2-Could it still be a switch?

3- Because the INST LP 5amp fuse also handles the "headlamp warning" and I do hear a beep when the fuse blows could it be something around that? Headlights come on and off, bright and
dim, go up and and down.

I do have a power on/ off switch wired up to the power wire that runs to the motors hooked up so I can cut the power off to the motors when the are not needed to raise or lower the
lights. It is just a simple interrupter switch to the flow of power though. It looks good with no shorting or damage to the wires.

Lastly as a recap of the oder of things.....this all started after I took the pod off to replace components for the ignition on the steering column while resolving a no start no rank issue due to a bad ground under the C500. Got car running, put pod back on, no gauge pod lights but all other lights in and out function properly and I keep blowing the INST LP 5amp fuse.

quote Originally posted by Scooter_86gt: I rechecked the fuses and realized when upside down I checked the wrong fuses...

Why "upside down"? Are you not aware that the entire fuse panel tips down?

Yes I know if flips down but the previous owner put in an aux temp gauge. The power wire is just that much to short running to the fuse panel and wraps around the fuse box corner so it won't come down all the way so to fully see the fuses I have to undo the box via the bolts or be upside down. I was up under there anyway as well.

Plus since everything is so fragile I would rather not pull out and put back too many things too many times in the fuse box ......on top of electrical not being my favorite thing. I figure best for me to contort under the dash than to create a new problem for my self by mucking up the fuse panel.....lol... .

Yes continuity can pass and have a short.
Plus if go by FSM etc to trace the board... Can't trust them for accurate images etc. Boards have charged over 84-88 models too but FSM often just have same image. Might help, see https://www.fiero.nl/forum/Forum2/HTML/138175.html thread accurately shows all bulbs.

unplug the dash and leave it unpluged, replace inst fuse then try w/o the dash.
factory radio clock/light and other lights should work and dim if dash has problem. Others include AT shift light, lighter socket bulb, and ashtrays I think.
both back plugs are used to light the dash... if works as test above then plug only one dash plug and try again. that should narrow the problem area because 50/50 chance will blow the fuse or not.

board pins can bend sideways when the "glue" won't hold. Look w/ a mirror to see the pins w/o pulling hole dash.

bulb sockets may test good and still have problems but usually won't short out. most times the metal and/or plastic cracks up and won't light in the dash.
LEDs can short out w/o being obvious but most times won't light some or all LEDs.
even standard 194 bulbs (and any w/ same contact setup) can short too when contact wires are bent.

Dash pod removed and fuse replaced.

I reconnected the transistor, then hit the parking light switch with no power at the fuse, no light to the AC/heater panel....I took radio out to inspect wires etc.

Next I jumped the transistor, hit the switch and the fuse blew and there was power on one side of the fuse.

When the fuse blew I heard a beep.

So that says the dash is not part of the problem, correct?

The fuse only blows when the transistor is jumped, regardless if the dash pod is in or not.

DASH LIGHTS NOW WORKING!!!

Thank you theogre, Chris Eddy and sardonyx247!!

The problem was with the hidden trunk switch I added. When searching for the short for the no start no crank I did a fair bit of moving wires here and there. I had accidentally broken open a taped set of wires in my make shift loom. Those two wires are not supposed to touch (light grey and dark grey from the old switch), well they ended up sticking to each other and that was the problem. I separated them, secured them and taped them up apart from each other so that will never happen again.

It was a great opportunity to learn how to test the switches and learn the full overview of that circuitry. Once I got my head around the diagrams I realized if I just unhooked everything in one direction of the fuse I could eliminate things one by one.....which is what worked.

Please note the the most common fuse blowing regarding dash lights will also take out your rear lights and other stuff....that is a completely different event than my issue. What happened to me would usually be resolved by jumping the transistor or checking the wheel all related the INST LP 5amo fuse.

Hopefully this helps someone else.

quote Originally posted by Scooter_86gt: The problem was with the hidden trunk switch I added. When searching for the short for the no start no crank I did a fair bit of moving wires here and there. I had accidentally broken open a taped set of wires in my make shift loom. Those two wires are not supposed to touch (light grey and dark grey from the old switch), well they ended up sticking to each other and that was the problem. I separated them, secured them and taped them up apart from each other so that will never happen again.

Homer says "D'oh"

LOL.....Exactly!!

Just out of curiosity, do your tail lights (running lights) work. Most cars that ive worked on have the panel lights in the same circuit as the tail lights. That was done years ago so that you knew the tail lights were out. I dont know if the Fiero works that way also or not. Your problem may be if they do, that you have a tail light problem, not a dash problem.

Never mind, didnt notice you fixed it. Ill leave my post up anyway in case it might help someone else down the road.

[This message has been edited by rogergarrison (edited 07-17-2017).]

quote Originally posted by rogergarrison: Just out of curiosity, do your tail lights (running lights) work. Most cars that ive worked on have the panel lights in the same circuit as the tail lights. That was done years ago so that you knew the tail lights were out. I dont know if the Fiero works that way also or not. Your problem may be if they do, that you have a tail light problem, not a dash problem. Never mind, didnt notice you fixed it. Ill leave my post up anyway in case it might help someone else down the road.

Fiero and other old big 3 cars have Dash Dimmer, Taillights, side markers and front parking are on same wire from HL switch, Fiero is HL switch pin E.

IOW Get power from 1 main ~20 amp fuse and same output HL Switch pin for most cars, but dash lights out isn't made to give warning except if has blown main fuse.
Fuse here in "inst lp" and only protects the dimmer transistor.

Some old cars have warning light on the dash that turns on dead tail/brake bulbs but this is rare. School buses have light monitoring for most external lights or just red/yellow up top. (Depend on state rules.) You could get aftermarket items, sim to this setup, to do this too but haven't seen them for decades now.

Newer cars then often all bets off. Switches don't run many things directly. If just 1 light is out then the BCM etc often knows and even can set other options to disable. Example: Kia SUVs w/ 1 blown brake light causes ESC Off and while you can turn on Cruise Control won't allow you to set speed.

A lot of the old big cars like Cadillac and some Corvettes used fiber optics ran from each exterior lite to show exactly which light was out. Usually a little panel in the dash or console was the display, and each fiber optic was 'lit' by the light given off each specific bulb. I dont know why all manufacturers didnt adapt that system.

quote Originally posted by rogergarrison: A lot of the old big cars like Cadillac and some Corvettes used fiber optics ran from each exterior lite to show exactly which light was out. Usually a little panel in the dash or console was the display, and each fiber optic was 'lit' by the light given off each specific bulb. I dont know why all manufacturers didnt adapt that system.

Because not require by NHTSA under FMVSS and they cost.

I've never seen as you describe.

Some old Caddy's, ~65, had a little box on the front of both fenders to display active front lights using crude "light pipes" made of plastic. I remember only turn signals and high beam HL. I had some of these light pipes after junking the cars. Only 1-2 feet long. I used them for a train set.

I had a lot of Cadillacs, Lincolns and Corvettes with fiber optics. Cadillac did use them on the front fenders, and also above the rear window so you seen them in the mirror. Also Lincolns had them at the rear window/ package tray. Some Corvettes had them in the center console. Ive also seen them in the dash. What I hated was junkyards that I bought things like harnesses and lights, would just cut them off thinking they were wires. On a customer car, if they cut it at the tail light and the original optic was also damaged, Id have to take out the seats and carpet, and whatever else to run a new fiber optic all the way from the light to the display. You could not use a broken one because light wouldnt pass thru it, even if you tried to glue it back together. The Cadillac front fender ones I remember had 3 optics, headlites, hi beam, and turn/stop light...I think they were white, blue and amber. Mopar fender lights, were actual bulbs, usually just for turn signals.

[This message has been edited by rogergarrison (edited 07-22-2017).]