1985 Dash Lights out
Thread Starter
Drifting
Joined: Mar 2017
Posts: 1,897
Likes: 164
From: Nashville TN
2017 C4 of Year Finalist
1985 Dash Lights out
The dash lights on my 85 are out. I read in This thread that a blown tail light can do this. I do have a blown tail light, but I find that hard to believe. I see that the tail light FUSE could be part of the problem, but would a single tail light do this too?
Note: I've tried two different gauge clusters, I was told at least one of them was working, but haven't actually confirmed that myself. While it's completely possible both clusters were bad, I'm also seriously questioning if there is something else going on before I buy an expensive cluster.
Note: I've tried two different gauge clusters, I was told at least one of them was working, but haven't actually confirmed that myself. While it's completely possible both clusters were bad, I'm also seriously questioning if there is something else going on before I buy an expensive cluster.
Zen Vet Master Level VII
Joined: Mar 2016
Posts: 5,218
Likes: 1,174
From: Southlake, TX
Yes, if you have a "blown" tail light you probably have grounding issues. Electricity will take the path of least resistance to ground itself out and often it is through your dash/cluster.
So, fix your known problem and change out your fuse.
Your (soon to be purchased??) shop manual will have clear wiring diagrams so you will be able to trace your electricity flow easily.
So, fix your known problem and change out your fuse.
Your (soon to be purchased??) shop manual will have clear wiring diagrams so you will be able to trace your electricity flow easily.
Thread Starter
Drifting
Joined: Mar 2017
Posts: 1,897
Likes: 164
From: Nashville TN
2017 C4 of Year Finalist
Yes, if you have a "blown" tail light you probably have grounding issues. Electricity will take the path of least resistance to ground itself out and often it is through your dash/cluster.
So, fix your known problem and change out your fuse.
Your (soon to be purchased??) shop manual will have clear wiring diagrams so you will be able to trace your electricity flow easily.
So, fix your known problem and change out your fuse.
Your (soon to be purchased??) shop manual will have clear wiring diagrams so you will be able to trace your electricity flow easily.
I'm buying the shop manual now so I don't have to ask stupid questions lol. CD Rom is cheaper, are they in pdf format on the cd usually so I could just print it out from there? Or some stupid proprietary format?
EDIT: I was able to read the fine print on the back of the cd in the ebay listing-it's in PDF! I will probably go that route.
Last edited by Bfenty; Mar 11, 2017 at 10:49 AM. Reason: more info
Zen Vet Master Level VII
Joined: Mar 2016
Posts: 5,218
Likes: 1,174
From: Southlake, TX
Not sure on your year but (if you have) your owners manual it will have a simple diagram of your fuse box.
There probably is a fuse for your rear tail light section as there is a LOT going on back there- brakes, running lights, turn signals....etc.
BTW... buy the book. It will be easier to set the manual on your front tire and flip pages while you spin your wrench than to scroll up and down while trying to balance your lap top on your knee.
Old school technology rocks.
There probably is a fuse for your rear tail light section as there is a LOT going on back there- brakes, running lights, turn signals....etc.
BTW... buy the book. It will be easier to set the manual on your front tire and flip pages while you spin your wrench than to scroll up and down while trying to balance your lap top on your knee.
Old school technology rocks.
Oil Producer
Joined: Apr 2014
Posts: 9,367
Likes: 2,735
fenty, if you want to get started cleaning and confirming your grounding locations are all in top notch order, you can Google 1985 Corvette ground locations, and I think you will find a diagram. Off the top of my head I know there is one on the rear of the driver side head it is quite a little rats nest of cables, to get a very good view point on it you could remove, temporarily, the wiper motor but this is not absolutely necessary.
The other location is on the driver side of the bell housing up near the top.
there are more locations to be sure as per a diagram that you find, but these two I can recall from memory when I rebuilt my 85.
getting these cars running in as new condition is a rewarding challenge, and much of it is trial and error. You are on the right track when trying to diagnose something as opposed to parts swapping, the amount of money required to get the cars running as new is high enough without all the extra part swapping.
there are more locations to be sure as per a diagram that you find, but these two I can recall from memory when I rebuilt my 85.
getting these cars running in as new condition is a rewarding challenge, and much of it is trial and error. You are on the right track when trying to diagnose something as opposed to parts swapping, the amount of money required to get the cars running as new is high enough without all the extra part swapping.
Melting Slicks
Joined: Nov 2007
Posts: 2,830
Likes: 147
From: Gainesville FL
Maybe your digital dash needs repair
Can you see the LCD elements when you shine a flashlight at the digital display? If so then you may have burned out lamps. If not you may have a bad power supply.
I just went through fixing my digital dash replacing faded polarizing film and changing the lamps for cooler running xenon bulbs. You can even find colored LED lamps.
You can find troubleshooting guide on youtube here:
About the FSM PDF CD if you go that route make sure the PDF file is indexed instead of one giant image file. You can't search the later for keywords or click on specific chapters.
I just went through fixing my digital dash replacing faded polarizing film and changing the lamps for cooler running xenon bulbs. You can even find colored LED lamps.
You can find troubleshooting guide on youtube here:
About the FSM PDF CD if you go that route make sure the PDF file is indexed instead of one giant image file. You can't search the later for keywords or click on specific chapters.
Instructor
Joined: Nov 2011
Posts: 139
Likes: 13
Quick and dirty way to check the ground to the cluster: Remove the metal access cover for one of the instrument cluster Halogen bulbs. Run a small wire (like 16ga) from ground, and touch the ground side of the bulb of which you removed the access plate. The cluster should light up and verifies that you have a ground issue. I've done this test on two cars I've owned in the past, and both had the same issue.
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Thread Starter
Drifting
Joined: Mar 2017
Posts: 1,897
Likes: 164
From: Nashville TN
2017 C4 of Year Finalist
Quick and dirty way to check the ground to the cluster: Remove the metal access cover for one of the instrument cluster Halogen bulbs. Run a small wire (like 16ga) from ground, and touch the ground side of the bulb of which you removed the access plate. The cluster should light up and verifies that you have a ground issue. I've done this test on two cars I've owned in the past, and both had the same issue.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
It is very common for the connectors between the dash PC boards to have crystallized (broken) solder connections. The ones to look at are on opposite ends of the connectors (+12 volts and ground). A poor connection will cause the area around the pins to turn black (burned by poor connection that gets hot).
Thread Starter
Drifting
Joined: Mar 2017
Posts: 1,897
Likes: 164
From: Nashville TN
2017 C4 of Year Finalist
It is very common for the connectors between the dash PC boards to have crystallized (broken) solder connections. The ones to look at are on opposite ends of the connectors (+12 volts and ground). A poor connection will cause the area around the pins to turn black (burned by poor connection that gets hot).
Thread Starter
Drifting
Joined: Mar 2017
Posts: 1,897
Likes: 164
From: Nashville TN
2017 C4 of Year Finalist
well, I have bench-tested the dash, and it works! So it's something in the car that's the issue. I think something is wrong with the LCD fuse (which the gauges won't come on without...right?). I looked behind the fuse box and there are two red wires coming out one side of it and nothing out the other side, like a wire came loose or something. I can't find one down in the dash anywhere behind the fuse box though.
You can see the two red wires going straight into one side of the same fuse here
Last edited by Bfenty; Mar 18, 2017 at 08:57 PM. Reason: adding photo
Thread Starter
Drifting
Joined: Mar 2017
Posts: 1,897
Likes: 164
From: Nashville TN
2017 C4 of Year Finalist
Quick and dirty way to check the ground to the cluster: Remove the metal access cover for one of the instrument cluster Halogen bulbs. Run a small wire (like 16ga) from ground, and touch the ground side of the bulb of which you removed the access plate. The cluster should light up and verifies that you have a ground issue. I've done this test on two cars I've owned in the past, and both had the same issue.
Drifting
Joined: Mar 2013
Posts: 1,952
Likes: 239
From: Venice Cali.
Mabey this helps I believe it is the large connector. I remember spraying electrical cleaner on the pins and inside the plug because it was very dirty.
Last edited by xrav22; Mar 18, 2017 at 10:05 PM.
Racer
Joined: Dec 2012
Posts: 347
Likes: 25
From: Rockford Illinois
If you're having trouble with the turn signals and lights there is a connector at the base of the steering column. Check that there are no loose pins in it. That was where the problem was in my 1985. I wasted my time checking on the grounds.