I've got multiple issues with my 1994. 87K miles, well taken care of...

1. The radiator cooling fans would not automatically come on when temps rise.

2. The after market CD/stereo comes on but will not do anything else.

3. The dash fans will not blow air out of them but the fans at your legs will blow out air.

4. The speedo/odo will work briefly, after less than a few mins of driving the speedo will jump all over the place before it finally will only read 0...once the speed only reads 0 the odo stops logging miles too. The speed sensor was replaced 2 years ago and this fixed the problem for a bit. After the car cools back down the speedo/odo will resume working for a few mins then repeat the problem cycle.

5. Check engine light comes on and off after driving the car for 10 to 15 minutes. It just comes on and off at various intervals.

I have had a fan switch installed so that the car can be driven without overheating for now.

Car runs and idles like it always has for the 14 years I've owned it.

Some say it's a dash cluster issue but I'm leaning more towards a computer issue since so many things are happening that possibly involve the computer telling various things what to do and when.

Don't want to take it to a local company that specializes in dash cluster repairs if that's not what it is.

Don't want to take it to the dealer and get ripped if it's not the computer but I need to know which place would be the best starting point AND if possibly these issues are all related to just one thing being wrong...

I'm wanting to sell the car but I can't with these issues even though the car looks perfect...who would buy a car with 87k if they noticed the odo not working at times. It just started but who would believe a stranger trying to sell a car that those are the actual miles......FRUSTRATED!!!

KTM - Welcome! Let's address these one by one. Thank you for neatly laying out the problems... it make's addressing/solving much easier!!

1. No fans... that could be a bad relay or fuse. I don't remember if the 1994's had maxifuses or fuseable links. If it has fuses, check the fuse panel behind the battery. Links are in the same place, but they are strips of orange wire that will break under load. The relays are located on the left side (drivers) of the radiator, near the hood hinge. Check them for function and/or condition.

2. Did the aftermarket stereo ever work? Does it have external amps or does it use adapters and the bose speakers?

3. That is a vacuum problem. On the right side of the intake, near the #6 injector, is a vacuum port. It has one line to the fuel pressure regulator, the other to the vacuum tank for the ac and cruise. Check that line. It has a check valve that is prone to breaking apart and dying...

4. The connector behind the speedo is loose... remove the IP, clean the contacts, and bend them all back to make them nice and tight. There is a great write up on that regarding IP problems just a couple of threads down!

5. You need to read the codes... IF the codes are legit, they will be stored in the computer. There is a way to do this via the IP... I think it is outlined in one of the recent threads on IP/voltage problems. I will track it down later, or someone will chime in. Your car is OBDI, so it is the old 12 pin connector. Most autoparts shops don't deal with OBD1 anymore...this means no free scans.

With all the problems, start checking grounds. There are two main grounds down in the kick panels... one on each end.

Finally, go to Ebay and get a PDF version of the Helm Factory Service Manual. They are about $15.00 and worth every penny.

Quote:

CODES: http://www.corvettebuyers.com/c4vettes/ecm.htm

Thanks for your responses!

I usually try to layout the details of the problems without being to wordy...It's the way I want people in my profession to tell me their IT/network related problems that I have to troubleshoot.

I will get the chance to work on the car tomorrow and over the weekend. I'll start by jumping pins B and A out to see what the codes are first then go from there.

I'm not a mechanic by any means but I can do basic stuff especially with some tips. I did actually change the water pump out on this thing and belts while I had it accessible....LOL....it only took me about 2 hours too!

Thanks again...

I did check the fuses and relays before posting anything initially and they were all good but still no fans. Everything looks good...I even jumped the fans out to make sure they would actually work and they did.

The after market stereo did work for about 10 or so years and it uses the same Bose speakers etc., with no amps added.

Video..... see if it helps (?):

https://www.youtube.com/watch?v=YEaWeEtOeJ8[quote]

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Oops! Posted the video (redundant) forgetting you jumped the fans.

If you work with computers, you can diagnose the problem. Don't have to be a mechanic to do that.

Proper diagnosis is 99% of the solution.

Where in NC?

Concord...Home of the "Charlotte" Motor Speedway...???

My ODB1 connection does not have a B connection, there is no wire/connection point there. It goes from A to C (right to left)according to the diagram included in your link...

Quote:

You may have the 16 pin connector. See http://www.aldlcable.com

From the above link:

There are other styles of connectors, but the 12 pin OBD1 connector shown above is the most common. Some 1994-95 cars have the 16 pin OBD2 connector (shown below), Corvette's, Camaro's, and LT1 cars among them, as well as newer Australian Holden and Commodore. Even though it is an OBD2 connector, it has an OBD1 system behind it on these 94-95 cars.

So is there anything I can jumper together to get codes on the screen in the car?

Quote:

You might contact - http://www.aldlcable.com - for assistance.

Here's how to do the codes.
May want to SAVE the pics
Photobucket is being w3ird

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Yes, I believe the info Don posted in post 3 is incorrect. Read this:

http://www.neilkline.com/Tech%20Tips/obdcodes.htm

And read the section on the 92/93 to know how to use the dash buttons.

This procedure is outlined it the FSM.

You REALLY can't work on a C4 without an FSM.

Quote:

Bill, you might present your analysis to the techs at http://www.aldlcable.com.

Where did you find those FSM pics Brian?

I thought I had them scanned and posted here (for '94), but can't find them???

edit:
found the link in another forum thread, but it takes you off the boards -
http://www.corvette-guru.com/modules/ ... t_id=49963#forumpost49963

Bill Matt Andy?

Quote:

YUP.

Got the same stuff here that Brian posted - this is '94 too:

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They came through now

Yea, the 94s and 95s are a hybrid as far OBD is concerned. It has an OBDII connector with OBDI software. My reader could read the codes on my 94, but it took a special connector.

I think the 96 was the only OBD II C4 as mentioned 94 and up was a hybrid between the two systems if I remember correctly