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Dash lights out, but no fuses blown?

T

tch777

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Help guys I can't figure this one out.
I noticed last week the dash light over the speedo went out.
Then this week all the dash lights went dead, and the running lights / parking lights front and rear are dead too. Plus the radio is freaking out flickering on and off unless you turn the headlights on then it is completely dead.
Also now when you turn on the head lights they are much brighter than ever before. And the coutesy light under the dash kind of by the ashtray turns on when you turn the headlights on, but is off if you turn the inside lights on.

So far I have replaced the headlight switch, and the bulbs in the tail lights eventhough none were burnt out. And no fuses are blown??
I searched the archives but could not find any solutions. Some other people had similar issues but they never posted back what fixed them.
The dimmer switch on the steering column was replaced last year too.

Update now I pulled the radio fuse and after I turn the key off it is still flickering. Must be a short somewhere, but where should I begin to look? I don't get how the lights are connected to the stereo???? By the way I have a Kenwood stereo installed it has been in there for 2 years now with no issues prior to this.

This is on the 91 suburban. BTW.

Thanks

Tim
 
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I replaced my light switch and my dash lights worked fine afterward, so check connections and grounds real good. Since your taillights dont work, its prolly soemthing having to to with your switch or something leading to switch (power maybe?) Its possible that you also have a bad switch. the parts store sold me a bad one once.
 
sounds like power is going to your radio via the ground (bad for the deck) i would check that out, problem could be in there
 
It sounds like a bad ground to me. Or maybe the bad dash light melted your printed circuit board behind the dash and some of the wiring is crossed as a result.

Wierd though, definitely wierd. Keep us posted, brother.
 
If your taillights are not working, check the plunger type switch behind the brake pedal bracket. I have started having a problem with mine. The plunger was nat getting a consitent 12V supply. This was and still is causing some weird stuff with the turn signals front and rear, the brake lights and the running lights. My Haynes manual has the wiring diagram for this general area. Look into that and good luck. Keep us posted.
 
Well I got all the bulbs replaced and no luck.
The brake lights are working.

But the running and parking lights don't work.

I will take the dash out today and see what I find.

Tim
 
Sounds like them damn grimlens again. You know the ones that randomly turn lights on and off in ur truck. I hate that one that steals my gas.
 
Well the dash came out and so did the radio.

Nothing is burnt up on the printed circuit in the dash.
And the some of the lights on it still work, like the 4x4 indicator, SES, and brake lights.

I also un plugged the radio and diabled the remote start unit.

Nothing I have not found a dam thing that has made an difference.

Is there are specific spot to look for shorts that is common?

there are wires everywhere under that dash.

Would the next step be to go thru the trailer light wiring harness?

ARR this sucks!
 
Funny you brought up the trailer wiring.

Last year I had to remove my trailer plug from the back of the truck after I started getting some funky **** going on with my signals and park lights. It ended up being a bunch of corroded wires inside the trailer plug. Once I removed it, everything went back to normal........

Maybe it will be that easy for you, too.
 
may not help much in your case, but where all my main cab wiring meets on the firewall inside the engine compartment, the starter selenoid's ignition wire pretty much relays all of the cab 12v. So you might want to check that one out and make sure it's good and clean. Good luck.
 
freaky lights...

i dont get to many in the dealer...well because 99% of the trucks that come in are 96 on up but aside from my own jimmy and a few blazers and pre 87 pickups i have encountered printed circut failure as the moderator mentioned,also the switch is a culprit as well in some cases. look at both and go from there. hope ive been a help in preventing a "trukaque":waytogo:
 
Saw many of these while managing an auto electric shop in Idaho. Either gain access to the dash and visually look for a melted wiring harness OR get a good wiring diagram and begin tracing the circuits affected (radio, taillights etc.) Do the front park lights work? If so, you at least know that the problem is just in the part of the harness for the taillights. How long after you used the trailer plug last did this start? It is common to wire a Chev. wrong. The aftermarket trailer plug (I'm assuming it's a 4 wire flat plug) has a white ground wire but the white wire in the rear truck harness is NOT a ground. This will let the smoke out of the harness somewhere. Good luck and good hunting.
 
I checked the printed circuit board in the instrument cluster and it looks brand new. I did change the switch with a new one from Napa with no changes. Can the circuit board be bad and not show anything?

The front parking lights do not work either.
We used the trailer lights 2 weeks ago. The issue started one week ago. And we drove the Suburban a bunch inbetween then. The trailer lights were added by the previous owner so no idea on how they were installed. But there is a brake controller in the cab and one of the big round plugs on the rear with a small flat 4 plug pigtail off of it.

Thanks for the suggestions

Tim
 
Maby Check your cig lighter. It is on the same circiut as the radio, interior lights, and some others. I had a cell phone charger short out and fkup my cig lighter and cause the same problems as you are having.
Also check all your grounds.
 
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Well I tried the lighter and it is fine disconnected it to check it out.
I did pull the switch and jumpered the wires I was able to turn on the dome lights, and the courtesy light under the dash. I was also able to turn on the parking lights both front and rear, but no dash lights.

Any suggestions were all of these wires come into a junction?
I will trace more of the harness tomorrow and if I dont find something it maybe time to rewire this little bugger with some toggle switchs and relays with my own circuits.

Also anyone know where all the ground points are so I know where to look?

Thanks

Tim
 
this may help...

I have a Haynes book with a wiring diagram..only covers up to 83,but many of the wires are the same color codes until 87,and are wired up nearly the same,if not identical..

There are brown wires on both front parking and marker lights..those are the ground wires..book shows them all coming together just before the bulkhead conector (near the firewall side of the fuse box).. the brown wire grounds at the radiator support near the headlights..I think there are more grounds under the dash--one black wire bolts to ground near the E-brake pedal--others are plugged onto a "bus bar" thats bolted to the firewall above or near the steering colum..

The dome lights get power by plugging into a spot on the fuse box..usually white and orange wires..might be worth making sure the fuse box isn't corroded internally where it unbolts--I've had a few trucks with gangrene connectors in there I had to cut and "bridge" the wires together,to get things working again...:crazy:
 
Well there is no love for me on this repair.
Got another switch but that was not it.
I did trace the wiring for a bit and I was able to get the running and parking lights to come on by pumping some wires at the head light switch.
I also got the dash lights to come on by jumping the wires at the head light switch.
But the wife did not like the idea of me wiring in some switches and relays to make it work.
I really like this vehicle, but it is a love-hate relationship. And the way I feel about it tonight is it a GMC, Gods Mechanical Curse.
Tomorrow it goes to the mechanic.
I will post back as to what the fix is, man it sucks when you ate close but just run out of time.

Tim
 
Well I am humbled yet again.
I checked all the fuses 3 different times with a circuit tester and they all showed good.
The mechanic actually pulled the instrument cluster fuse and lo and behold it was burnt! Needless to say the circuit tester is now dead and I will rely on the good old time consuming pull and replace it method for fuses in the future. Also the power and ground connections to the radio were loose only the memory power was hooked up causing all of the wierd radio gremlins with the key off and all.
Last but not least the battery was dying and after getting the truck home from the shop gave up the ghost.
There is a new Red Top Optima in her now and everything is working great. I even had to replace the terminals on some of the auxillary wiring as corrosion had eaten up into the insulation. The stereo is much loader now since the amp is getting full power again.

Thanks for all your help

Tim
 
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