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Hi Everyone,
Back in a Corvette, after owning a couple C3s a few years ago, I've been without a Vette for awhile, focusing on my F-body and British Car (MG's and Jag's) habit; but the looks of the C4 have been slowly growing on me to the point where I found myself wanting one. This red on red 85 Z51 Automatic showed up locally and I was able to get the price down to what I thought was fair for a car needing some work, so I grabbed it and brought it home today. The car looks OK from 10ft and it runs/drives fantastic, but needs some interior cosmetics and a few small repairs. I'll start with some photos.
First thing I noticed on the outside was that the rims don't have the black centers I would've expected on an 85. Have they been swapped with an 86/87? or maybe some late 85's (this one is June 85 production) got the 86 rims?
The two issues I am trying to sort out first are:
1. The digital dash is a bit wonky. Most of the time it's lit up very faint but doesn't show any information, but as you drive along it'll occasionally come on a little brighter and will start to show all the info. I know the Batee site is the best reference to dig into here, and I haven't had a chance yet. Is there a popular diagnosis based on these symptoms?
How it usually is (note, I removed the bulb covers to see if they were lighting up)
When it does come 'on' after driving around awhile:
2. The blower motor doesn't come on. No matter where I put the slider (AC, Vent, Heat) or the fan speed setting, I get nothing. Is this a common issue? Any recommendations before I start chasing it with the voltmeter?
Onto a few cosmetic questions:
1. The leather on the handbrake pull is torn. Is there an aftermarket solution?
2. Above there radio, to the right is a large black panel that looks like it should light up. What is here? All I've seen light up so is a 'fasten seat belt' light...
The black panel has a name (That I can't remember) but it's where a bunch of the "Idiot Lights" and other important info gets displayed. Things like "Check Engine", "Security", "Overdrive Engaged", and other things you need to know are displayed there. I like to think of it this way....if nothing is lit, you are probably good-to-go.
Highly recommend purchasing a GM Field Service Manual for your year. Super informative. eBay usually has at least a couple (Either hard copy or electronic version) available on most days.
DIC- "Driver information center" for the black area where the "fasten seat belts" light is and others. The film with the different symbols/words in this, is called the "tell-tale filter". '85's should have black centers and black pockets for the wheels. Blower motor is on the engine side of the firewall on the passenger side, easy enough to get to and test. Unhook it and turn fan switch on and check the plug for voltage. You can also run a jumper wire over to your battery (when factory wire is unhooked) and see if it runs. Check the connection coming up from the starter towards the back of the passenger exhaust manifold (between the manifold and the frame) often this plug will be green with corrosion (should be brown plug with 3 wires). I'd start there, then onto the blower motor relay, etc until you find your problem. Hope this helps👍
Thanks Guys Looking forward to digging into this as time/weather allow. I agree on the tires, they are dated coded 2005 so well beyond highway safe. So far I've only puttered around the neighborhood, but once the car is up and running new tires will be at the top of my list.
The brightness is related to the photodiode but most problems are from the interface connector between the boards. Replace the hot bulbs with LED, use a brass brush to clean all the connector contacts, touch up solder on the interface connector (long wire header sandwiching the boards). That is a good general start. You will most likely see some carbonizing of the board from the hot bulbs. clean with alcohol and brass brush. Reflow solder on contacts if still black. Dash usually looks great after that. use flashlight on upper left corner photodiode to force dim/bright circuit for diagnosis. Oh, the 89 dash has the power supply integrated if you ever need to replace the main board.
Car looks pretty good from 10 feet as you said. Seats are in good condition too. I am jealous (better than mine at least).
Thanks, I have the digital cluster out of the car, but I haven't had a chance to dig in yet. My intent is to sit down and watch the Batee videos and then go through it to see if I can find the issue, I also want to check the ground in the car before going to deep into the cluster. It does sound like I may have a problem with the interface connector, so that's going to be the first thing I inspect when I get the cluster opened.
02-28-2021, 05:56 PM
First C4! Project - Help with Some Basics
Looking forward to digging into this as time/weather allow. I agree on the tires, they are dated coded 2005 so well beyond highway safe. So far I've only puttered around the neighborhood, but once the car is up and running new tires will be at the top of my list.
