Hello Everyone,
Hope everyone's Hollidays went well. Happy New Year !

My 1987 GTA LB9 5-SPD was taken to a csr audio store right after the purchase. In 1987, the original owner spent somewhere around $4300 on his new sound system and alarm. It was all Alpine, and all "top shelf." The Alarm system was the baddest boy you could get. It has window sensors, hatch sensor, tilt sensors, this sensor, that sensor.....sensors every where a sensor could go. With the stereo and alarm, plus the 64.765 sensors, comes all the wiring....And all that wiring requires the factory harness to be freaking Ginsued, They ALL ALMOST had it done correctly..unbelievably, they took a great deal of time and soldered all the spices.. Nice , neat, and all most all pretty like...But the knuckleheads used darng DUCT TAPE to cover said soldered joints..Plus they re-routed much of it going back in. They had re- run wires too close to part of the exhaust, and left a frog hairs lenght of slack...
fsat forward 39 years and i have a huge casarole of nonsense...I've cleadned up 3 or 4 parts ive came across so far....but my main issue noe is i have no dash lights or running lights/marker lights. My blinkers, hazard lights, brake lights, reverse lights all work. CES light works... there's just nothing illuminating. Checking fuses w/multi meter, I discovered that the INST 5A slot has no power. The fuse is good, but no power to it. I believe it gets its power from the grey wire attached to the back? I follow the Grey wire around and loose it as it goes into the harness right above the fuse box, where 2 system ground wires are. I researched some,, but couldn't find an answer. I had a 2 wire connector under the steering wheel, behind the hush panel that was not attached to anything, and as far as I can tell, there is nothing that is unplugged. Its a pink/black stripe with a solid purple. They were hanging down fairly close to where that grey wire from back of INST on fuse panel was.. So i just put a fused jumper connecting the grey / pink black stripe wire since it was only powered when the ignition was in " run"
once again, all was well in the world. I had my marker lights back my dash lights back, everything that I had lost was back. But then earlier this evening, I was back to no dash lights, and something is causing my fused jumper to pop fuses. I did switch head units, but the car did fine for about two weeks.. I took it out just to make sure I didn't goof and wire something up wrong, but it didn't resolve my problem. No other electronics, we're added,
i do have a service manual and have looked in it but i'm not familiar with navigating those things yet. It's kind of confusing, and all I can find about no illumination is just with the digital cluster which I do not have.....
i did search the form before asking this, but the few then I found it didn't help or really didn't apply.I felt. Any help would be greatly appreciated

 

The dash lights get their power from the tail light circuit, at the head light switch (i.e. they work only when the tail lights are turned on). If you have no tail lights and no dash lights, first thing I'd look at is the HL sw.

Wires are color coded. In every GM car, wires of a particular color are all used for hooking up the same things. It's not that hard. Not sure how anything at all about wiring is "confusing", but w/e.

Pink/black is switched ignition to ECM devices. Don't hook lights to that. Don't EVER just randomly "splice" wires together, of any color, at any time, for any reason, even if it seems to "work" at the time; that most often just ends up making problems worse, by damaging something unrelated to whatever the problem originally was. IOW it's like a disease that spreads as it infects new parts, using the human as its vector. Don't be the disease.

Grey is dash lights, after the fuse. The wire from the HL sw to the fuse box, the one that brings power FROM the HL sw TO the fuse, is dark green. The voltage on that wire will vary depending on where the dimmer is set. Turn the **** all the way left, it gets full voltage; the farther toward the right you turn the ****, the less voltage there will be, and thus the dimmer the lights will be. Full right turns them completely off. Firebirds also have a "dimmer module" for some reason, that's not in most other cars; it's nothing but a 2N3055 transistor mounted on an aluminum heat sink, which serves as an amplifier of sorts such that the full dash light current doesn't go through the dimmer potentiometer, and it goes bad often. If memory serves, that "module" is in the green wire circuit, between the HL sw and the fuse. If the tail lights work butt the dash lights don't, that's the next thing to look at.

 

Hello, thank you for the reply. I was pretty flustered when composing the thread. I never stated what i had changed. The oil pressure switch is new, the headlight switch is new, battery is new, have also replaced the transistor on the heat sink.
the service manual, for me at the moment, gets hard to follow with the bouncing around. Searching one place to look up the name of a part (the schematics for a parts location has names on some, but most are # so I have to jump back and forth from schematic to definition⁶) go to one place for the "test procedures" another for diagnosis then the flow chart for resolution....I just need more time to familiarize myself with the manual.
Ill go double check for a dark green wire, keep checking for grounds....

 

Don't bother with "flow chart". It's just lights. They glow when they have voltage across them. Pretty straightforward. Just use logic, reason, and discipline. No mumbo-jumbo, no alien visitation, no "mysteries", etc. If YOU decide beforehand FOR YOURSELF that you're not confused, then ... you're not confused. If YOU tell YOURSELF that it's confusing, then you WILL BE confused. Confusion is all in your head. I used to be a math teacher (statistics, specifically); the FIRST THING that always had to be done for many of the students, was to convince them that it wasn't "hard", and that "good at math" is just a state of mind that THEY have control over. Once that unnecessary unfortunate self-imposed internal mental hurdle was overcome, it suddenly became easy for nearly of them. Same here. Don't outsmart yourself with all that ... other. Don't be afraid, you can do this.

If the inst lp fuse has no voltage on either side, then it's a 12V problem, not a ground problem. Don't bother even thinking about "grounds". Logic, not mumbo-jumbo.

Follow the voltage from the HL sw. Look for 12V on the dark green wire, with the dimmer all the way to the left but not clicked onto the dome light detent. That wire should end up at the transistor. There should be full-time 12V coming into the "module" also; I don't have a Firebird schematic handy and I'm not totally familiar with them, butt I'm inclined to suspect that it's going to be an orange wire (fused full-time battery, from the CTSY fuse, same power feed that goes to the radio memory, dome lights, & cig lighter) since orange is the universal GM color for that fused battery circuit in the interior. Some Firebird person is welcome to correct me if it's some other color. In any case there should be full-time 12V on at least one wire going into it, since the dash lights are supposed to be able to light up no matter whether the key is on or not. Obviously if that's not there (i.e. no 12V going in), there can't be 12V coming out, either. Since there's nothing else in the inst lp circuit besides the HL sw, dimmer pot, dimmer module, and acoupla wires, then ... nothing else ... can be the problem, besides those items. It's just logic, nothing "hard" or "confusing" or requiring "chart" about it.

It does sometimes happen that the connectors on the back of the cluster, where the harness plugs into its flexible circuit board, can go bad. Not often butt not "never" either. If you find that there's 12V on the grey wire all the way to the cluster butt the lights still don't light, then that could be the cause. However you're not really quite all the way there yet so don't worry about it yet. One step at a time. Fix whatever is preventing voltage from getting to the fuse first, then if the lights still don't light, work your way farther downstream toward them.

You mention that you replaced the transistor. What part # did you use?

 

I got my Inst Lps working by attempting the diagnostics, basically. Actually bothered to pull the cluster, etc, and physically checked for 12v at every junction point in the circuit. Stuff must have been too corroded to make contact or something but by the time I kept following the power to the fusebox, it was going all the way through again.

Not to say that'll fix your problem but chasing it down one step at a time isn't a bad way to get started.

 

Hey man!,
thank you for the reply and sharing your experiences. I appreciate it very much. Im fairly new with the "newer " screamig chickens. I had a 77 W72 for a while before my 87. It was highly optioned with power locks/windows, cruise, am/fm/8track, rear defrost, and even the trunk release button in the glove box.....but even with all that (lol) the wiring was pretty simple. But in my defense, im Aggie by blood. So you know, the long way around and twice as hard is usually how it goes. But because it's just a blood relation, it cant be used against me.
State Law
just joshn'
but I believe ive got the problem area pin pointed....this was one if the nonsense casaroles I was talking about.....I believe my issue in this. I cleaned it up after I found it, but I'd bet someone's pinky toe i goofed in there somewhere in my clean up job. That was under the clutch fluid reservoir and brake master cylinder. Behind the spaghetti of stainless steel brake. lines

 

Thank You Very Much sofakingdom. Awesome stuff!
but you know, usher, do wish those engineers would have kept your words in their mind.
" Just use logic, reason, and discipline. No mumbo-jumbo, no alien visitation, no "mysteries"
the number of functions that are activated via a signal from some other part in these cars is just really silly. Like the sequence for the burnoff feature for the maf....
math was never my strong suit in school. I did well enough to pass, but I figured my life would be a little easier with math on my side, so I fell in love and married an Asian woman. But my fix, yes, sir, was going to be temporary. It was just he biden time to try and figure out where my power loss was coming from. With the wiring harness being completely gutted and put back together and ran different from the factory set up, some things, even as easy and simple as they seem take a little longer. Trying to decipher my relays was real fun. half of em are not in the correct spot. Some are switched around, in some are just tucked in a body panel somewhere. I worked for an electrical supply company for years, I would see electricians with burnt controls, switches, over loads, etc. more than a few times from jumpering, gone wrong.
Electricity and math are very much alike in it only works one way. In hurts like heck, when you do it wrong haha.
but when you were talking about the colors and what functions they were dedicated to I remembered cleaning up a bunch of red wires underneath the brake booster, brake master cylinder area. I'm going to bet my cleanup caused my issue.It may look better but certainly doesn't work better..
thank you very much again for the advice and sharing your knowledge. It's never a bad day when you learn something new...
I will get it knocked out. No question, I will definitely keep you posted.

 

And I apologize.My voice text is a bit of a crackhead.Sometimes. forgive the weirdness.In spots. Hahaha

 

Sofakingdom
i don't remember the part number of the transistor and I can't seem to find the receipt. I went to what would basically be like a radio shack for the oil field and they crossed it. The only difference was the power dissipation. I believe was one 145w from 115w. I still have the factory one cause I was not a 100% sure that it was bad. But as cheap as it was, I didn't feel it was much of a gamble.
thank you very much.Again.I do greatly appreciate it

 

That wiring in the photo is .... VILE. That's more like steel wool than wiring. Hard to see how much of it is factory. It probably doesn't have anything to do with the dash lights, butt should DEFINITELY be sorted out for its own good, regardless.

It's always harder to find the faults when a car has already been heinously butchered like that. I can tell you all day long what the factory colors are, where the wires go from & to, and all such as that; butt when some yutz gets their dykes into it and starts doing stuff like that, it DOES add a certain level of "mystery". There's NO WAY anybody else can POSSIBLY "know" what damage and destruction the 2-legged rodent did to it once it got loose and crawled in there. Only way to "know" is to trace every single wire, looking for and erasing all the pecker tracks as you come to them.

So yeah, identify which of those wires are factory, and which are not (usually not hard to tell just by looking at the materials), restore all that to the factory configuration with good solid crimps or soldering with secure waterproofing, and continue on. I'd ordinarily tell people to concentrate on one thing at a time; like, if you're working on dash lights (a system contained entirely within the car interior) you should leave whatever is under the hood, alone; butt stuff like that is a FIRE HAZARD at best. If that all is connected to the factory's original red wires (red is the color code for pre-fuse hard battery) then it could BURN THE CAR TO THE GROUND if it gets loose and touches something somehow. The 2 red wires coming out of that one split-loom don't look factory to me for example butt it's hard to be sure from that photo. Looks to me sorta like somebody installed an alarm or emote starter, and it went bad, and then Skillet got in there and "fixed" on it until it worked just enough for the car to run just long enough to sell it.

The transistor # I gave you is an extremely common one, or was at one time at least. All of those old JEDEC numbers are disappearing fast nowadays. Lots of retail-ish places carry the NTE (New Tone Electronics) line of replacement parts for DIYers, hanging on yellow cards with blue printing; their # for it is NTE3055. People on here use that part all the time and it works just fine.

 

So i have just 1 or 2 issues left. One is the factory stereo wires. So where the stereo wires come up into the trim or shroud, the orange is constant power, yellow is ignition switch power, the light green/green are front speakers, the tan and bigger gray are front speakers, black is ground? brown is dimmer, but what is the small gray supposed to connect to? I cant seem to find what it connected to. There is an aftermarket stereo. The one that was in it when i bought it was toast. I had it replaced but it crudded out too. The person who replace it before isn't available so im kinda lost. I have the tail/marker/running lights back. Brake, blinkers, reverse lights all good. I have power back to the 5a inst fuse socket, but still no dang cluster illumination. The factory transistor in the remote dimmer was good actually, so i put it back in. New headlight switch, dimmer, and ignition switch....
If I connect the small gray and brown wire behind the stereo, ill have illumination, but not for long. The tail fuse pops when I hit the headlight switch. Im going to disconnect the harness going to the tail section, behind the glove/storage box on drivers side (i believe) and see if the tail fuse still pops.
but what im really wondering, is what the small gray wire goes to behind the stereo.
appreciate all the info Sofakingdom.

 

The brown wire isn't directly for dimming; it's power for the parking lights/taillights/illumination. But for illumination, it also runs through the remote dimmer, along with a dark green/white wire, and a dark green wire exits the remote dimmer and goes to the INST LPS fuse, where the grey wire exits for dash and radio illumination with the variable voltage for dimming. Here are the pages in my 1987 Firebird Service Manual (photos because my laptop won't import from my printer).

From the lights switch to the remote dimmer then to the INST LPS fuse:


From INST LPS fuse to the illumination distribution, including the radio:


Radio with subwoofer (Performance Sound option w/GAIN switch, which I didn't notice if you said you have or not):


Radio without subwoofer:


Here are the connectors. The grey wire fits into the connector next to the black wire. And the brown and orange wires go into the small connector.



And the pink/black wire you mentioned comes from the gauges fuse:

 

Hey LaFireboyd,
thanks for the pics man. The factory radio harness was hacked out long ago. The original owner took it from the dealership to a stereo shop and spent around $5300 ( like $15,000 today!!!!) on a stereo and alarm system. It was all Alpine. All din cable powered. Alarm was the Alpine 8122 /8121 series. That sucubus s.o.b. was apparently the baddest system in the know universe apparently. The installers hacked into every facet of the entire wiring harness. Sensors here, sensors there, sensors every freaking where. They not only hacked the harness with Ronnie Millsaps eyes, but used Ray Charles and Stevie Wonder to re run it when they were done. Very little was re-ran where it was supposed to. They split groups of wires out of the fact harn to run with their wires for a/group componant(s) a sensor was protecting. Then laid it back in the car with the main focus on making it easier to place/service/possible repair to their equipment. Those hill billy sister kisser knuckleheads had no regard to where they re-ran the remaining factory harness or even the newly "built" harness'. Nor did they think about things like heat from manifolds, heat from radiator hoses, possible weather from mother nature, servicing parts, or the longevity of any of it. Like my tps sensor connector had about -.05 inches of slack. Some wires you could have strung a bow across and got music notes.....I have near divorce amount of hours trying to unravel this spaghetti on crack and lsd mess....
So anywhoose....
the pink/black wire i jumpered to the grey wire coming from the back of the inst5a fuse slot was in a connector with a purple wire. I was just the pink/black and purple wire and it was hanging down directly under the steering column. The grey wire was coming from the back of the fuse panel came around it, and right by where the 2 ground wires are, under steering col/ on left. It went back up into a group of other wires wrapped in tape. It looks factory, and correct but idk what all the wires are or colors cause its tight wrapped and little to work with. It goes back up behind the inst panel, behind the frame work. After reading older posts , it might be the conglomerate of gray wires that all come together to a point. I believe its behind the ac controls. The wires from the remote dimmer to the light switch/dimmer wheel seem fine. Not damaged. But again they're all wrapped still and run behind the framework of the gauge panel. The light switch is new, dimmer wheel wheel isn't, but voltage adjusts when the meters on it. All marker lights work, courtesy lights, map lights, dome, work. Shift indc light works, blinkers/haz, reverse...all work. All gauges work. Cig lighter works. Armrest/console light i believe works.....
but still no cluster illumination/ac contro illumination. Where the factory deck wires come up from the floor into the radio shroud, she just had the regular stereo- not with factory subs/amps and all- I feel my illumination issue is in that somewhere/somehow. As I stated, I just dont know where that grey wire goes. Well , or the brown wire. I had them together and dash lights worked, but temporary only. It was blowing the tail fuse. Isolated the issue to somewhere upfront. Pulled after market stereo out,;unhooked the brown/gray wire and now the inst5a pops when lights get turned on. Tail fuse is good now though. Again, on older post, I read where the issue could be with door switch(s) or the tiny light for the shift pattern plaque, (i have the 5.0 and T5 trans) which i need to replace that. The tiny bulb and wires are jacked up completely. but i need to make sure its terminated correctly. Can possibly be one/some of the little illumination bulb(s) in the cluster. I didn't notice any dark spots, so im not thinking thats it... Im going to pull the ac controls to see if I can find if the the grey and brown wire were connected there somewhere.
Ill double check the schematics you sent, I appreciate it very much. And actually, after looking at it, that little grey wire may connect to the black one it seems. But running lowbon spare fuses lol. I have most of the fsm, but its fell out/off of the the binding. I did receive it and an 8-12 space accordion style folder with (what i was told) every reciept from each owner since new. I am the 4th. It also came with a black book that had date, time, weather, temp, gals of gas used/filled and avg mpg from the 1st owner up to 78k. 2nd owner continued with a blue book till 98k. 3rd owner had a flat spot develop in cam lobe so everything was rebult at 129k. Motor, trans and clutch, brakes and suspension and added cat-delete flowmaster exhaust. It was very well taken care of so its sad that those coark soakers were such...well....coark soakers. I have a pdf of the 88, but idk if its the same.... so again thank you very much. I appreciate it....
ill post resolution soon. Or test the no questions asked claim process from Haggerty Insurance lol...

 

If you're returning it to stock, and the car's connectors are gone, then this is what you'll need to connect to the car's wiring that will then plug into a factory radio. You can find it on Amazon, ebay, possibly in auto parts, and maybe in electronics stores that support cars, which is probably just Best Buy nowadays.
Metra Electronics | Products

The wire colors are "universal," so they don't necessarily match the colors of the wires in the car, so you'll have to know what's what when you're splicing it in. But there are only 12 wires, and 8 of them are for speakers, and they usually all have printing on the wire insulations for their purposes. Or if you have access to junkyards, and you can find an 82-87/88 3rdgen, then cut that section of the harness out, and then you'll be able to match color to color, which will be easier for you since your wires are laying lose.