This 1985 Corvette is driving me crazy. I first picked it up 2 years ago for $6000 from a mechanic. He said, "This car is running rich. I've replaced the computer..." I don't remember much past that. Being the age of 18, all I saw was a shiny Corvette. I tried starting it the month after I bought it. It was quite chilly out and the car would not start. My father and I replaced the injectors (except the cold start injector). We managed to get it to turn over, but it wouldn't idle without me holding down the gas pedal. It sat for the remaining two years. I pushed it out of the garage the other day, put a couple gallons of gas in it and it fired right up. I think I shed a tear when it started. Haha.

Problem #1: What would cause it to not start and idle on its own when it was cold outside, but then start and idle on its own with no problem when it was warm? I'm assuming it's the cold start injector.

So, I noticed a couple fuses were blown in the fuse box. I went out and got now fuses and replaced them all, as they looked like they haven't been touched since 1985. I noticed that after I replaced one, the lights on the inside came on. I figured it was the fuse for the door sensors or whatever. At the same time, the security light on the center console started blinking. This is where I had my "Oh shi-" moment. I went to go start it, but now it won't. It'll crank like nobody's business, but that's it.

Problem #2: Is there a way to disable or repair the issue with the security system? I would assume something is up with the chip in the key or maybe a wire in the ignition?

This issue isn't as important as the previous two; or maybe, it is. The dash cluster isn't lighting up like it did when I first bought it. Additionally, the turn signal lights and the brights light are staying solid on the dash. Here are some pictures so you get an idea as to what is going on.

Problem #3: What is the cause of this and how do I fix it?


Also, could someone give me an estimate as to how much these issues will cost to fix myself?

 

Well, BEFORE you do ANYTHING else....

search and BUY a FSM set otherwise you don't stand a chance with a "basket case" C4.

The books are so detailed that My mom could fix the car.

To your immediate probs...
#1
many things. CS inj maybe, check the CS temp sensor in the intake under the throttle body and the wire to it.

even If the CS was not working right it should still fire and run when its cold. Just takes longer to warm up. You NEED to see what the fuel system is doing. Pressure, how well it holds and how long. You also need to understand the fuel system....its far more complicated than you think.
To start on #1, fuel pressure, temp sensor and ohms test the injectors.

#2 If the starter works the security system is NOT the problem. You CAN bypass the starter interrupt relay but that's most likely not been done YET.
In 1985 I do not think they had incorporated a fuel inj disrupt link to the VATS or that yrs security system...so you are seeing the old problem. Ignore the flashing 'security' lite for now. Nobody really knows what it means when it flashes at what time...but its a great way to THINK you found a non-problem and blame the security system.

AGAIN...go thru the basics..fuel, pressure, inj pulse (noid lite) and spark.
There are inj fuses that need cleaning. You also MUST go thru the small jumper post behind the battery and clean EACH terminal on there and check it. Those are the power connections for EVERYTHING on the engine and ECM...if they are dirty it will not run.
THEN>>
you need to crawl under it and find the set of harness grounds somewhere above the oil filter. 5 wires on a bolt...on the block or bellhousing. CRITICAL. The entire car is MANAGED by GROUNDS. NOT power wires...its hot all the time. Its the GROUNDS that matter.

#3 Go to Batee.com if you have the nuts to tear into a solid state circuit board and do some soldering......then proceed. IF NOT then search the corvette catalogs and web searches for Digital cluster rebuilders and exchanges...they run about $350 to exchange. or you can do it yourself @ bate for free as long as you send him a donation to keep the web site up.

Once again, the NEXT dollar spent should be on the FSM set....otherwise the next dollar will be wasted . The 2 book set is $75 used on fleabay or $100 new. There is a link here if you search.

 

I have a Chiltons Repair Manual. I guess I'll have to just buy a FSM...

 

Since I just read Gordon Killebrew's book on the digital dash cluster today... He says this is caused by a bad ground. The one to check is on the A pillar to the left of the pedals. You'll have to remove some panels to get to that area. I haven't been in there in a LONG time so I don't remember the details.

There is also a ground point on the top left bell housing bolt. He recommends removing the windshield wiper motor to get to it. My '86 has the grounds on the side of the block above the oil filter so I've never done this.

 

Flashing "security" light in any year C4 means a door is open, the security system is NOT "armed", and the ignition is off.

 

 

I have heard all the hoopla about the FSM but be aware the layout of it leaves alot to be desired!!! Bought one for my 96 and it does have a boatload of info but trying to find a certain component takes forever!! For example, I have an intermittent start problem on my 96 LT4. A Corvette mechanic told me it was the clutch switch or Body Control Module. Tested and it's not the clutch switch and after a week of searching the FSM I have yet to find the BCM!!! I know it's there but can't find it in the FSM????

 

the NEXT dollar spent should be on the FSM set....otherwise the next dollar will be wasted

Best advice you could ever get!

 

They took some shortcuts, that's for sure. Some interesting things I've found in my 1986 FSM:

The TV cable adjustment procedure has pictures that show a carburetor.
The whole section on rebuilding the 700r4 seems to be generic.
The 700r4 section shows a "shift quadrant" like you would find on an instrument panel instead of a center console.
The section on transmission pressures shows a wide variety of transmissions, but nothing on the MD8 version used in Corvettes (the pressures are much higher for a Corvette).
None of the 11 700r4 internal wiring diagrams look like they're for a Corvette.
The section on the heater water shutoff valve shows a valve for an '84.
The spark plug wire routing diagrams show some wires going in FRONT of the distributor cap, but that is impossible because there is not enough space between it and the rear of the plenum.
They talk about a "convenience center" with various relays and flashers, etc. but Corvettes don't have one.
The description on how the C68 HVAC programmer communicates with the HVAC control head is completely wrong.
I looked through the wiring diagrams in the back for the wiring for the auxiliary fan and it simply wasn't there.
The ALDL connector diagram shows something in cavity D but there is nothing there (Agent 86 tipped me off on that one when I posted a picture of it -- but I had already marked up my FSM prior to that).

 

its in the electrical book.

if you look at the table of contents there is a list of 'sections' and you have to figure out what your particular question is in relation to an "area" of the car. For ex, if your headlites do not go up you would not look in the chassis section. it would be in the elec book under lighting, then sub-section head-lite actuator motors or some similar title.

Looking for the info is not a big deal. Not having it IS.

 

I had very similar idle issues. Since your injectors are new i would assume thats not the issue but should be tested to be certain. In my car my injectors where also new. I would look at the IAC, i replaces mine and my car instantly idles w/o have to give it gas to keep it running. It stil edled high after that, After going through flowchart on FSM, I replaced the ECM and now car idles like a champ. Also when yo buy a FSM I STRONGLY recommend the Digital version as it's a PDF and it makes looking for topics lightning fast with the search function.

 

I agree, sort of. The learning curve can be confusing at times. I found post-its really help 'finding where you were yesterday with out grumbling.

Bill

 

I have a 85, ive been restoring...these guys are a lot of help but until I took their advice and bought a fsm....peeing in the wind....get one.