Who makes a 1994 OBD 1 corvette code reader?
Instructor
Joined: Feb 2011
Posts: 244
Likes: 6
From: harrison twp mi
bought the cable and datamaster program,and after alot of frustration and not being able to get anything to work.used the paperclip method and it only took about 30 sec to do.
thanks for some more good info guys.
mike
thanks for some more good info guys.
mike
Platinum Supporting Vendor
Joined: Feb 2004
Posts: 1,771
Likes: 37
From: Sawyer MI
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
Use a paper clip, bend it to fit in #4 & 12 port ( 12 is directly below 4) turn key on (DO NOT START) codes will appear in the speedometer spot. Write them down! (turn key off & back on if you need to read them again) take key out and remove paper clip. go to Corvette Central to get correct codes for a '94 (some of the codes differ from other years).
'94 was the transition year for OBD 1&2. It still runs on OBD1 but uses OBD2 plug. Corvette Central is the only place I've found correct codes for those of us with '94s.
'94 was the transition year for OBD 1&2. It still runs on OBD1 but uses OBD2 plug. Corvette Central is the only place I've found correct codes for those of us with '94s.
Don't need a scanner the on board works great and will tell you the information in all modules. A scanner will only talk to the PCM which is module 4. 
Check these links for how to do it and the info varies.
http://www.corvettephotographs.com/c4vettes/codes.htm
http://chevythunder.com/199295_lt1_trouble_codes.htm
http://forums.corvetteforum.com/c4-t...-retrieve.html
2nd Gear
Joined: Mar 2011
Posts: 2
Likes: 0
From: Woodstock GA
The paper clip will give you the codes, but if comes up like my '94 that had a rough idle, you may need more. I didn't have any codes and the car passed emissions, but had a rough idle. I have a Actron CP9190 code scanner that does ODBI and ODBII cars and also displays real time information from the PCM while the car is running. Using the scanner I could see the Long Term Fuel trim at idle was showing that there was excess air. I started looking for vacuum leaks and found two. The check valve that supplies vacuum to the A/C controls and the cruise control was leaking. Also the EGR valve was bad, carbon had built up to where it wouldn't close completely. The scanners with the ability to display real time data are invaluable for troubleshooting the FI cars.
Burning Brakes
Joined: Nov 2009
Posts: 828
Likes: 103
From: Olney MD
Six year old threads... aged like fine wine
I thought I was the only one who posted to six year old threads!
I just bought a Auto Xray 3000 with the OBD1 software from Amazon. So Far, so good. I've used it as a scan tool and gotten the codes I needed and cleared them.
Next step is to record the ECM measurements while i'm driving and play them back on my computer.
For $100, it's not much more expensive than a scan tool alone.
Supposedly upgradeable to OBD-2, but since I have a 93 I'm not in a hurry.
I'll post to this thread when I get the upgrade (maybe in 5-6 years?)
I just bought a Auto Xray 3000 with the OBD1 software from Amazon. So Far, so good. I've used it as a scan tool and gotten the codes I needed and cleared them.
Next step is to record the ECM measurements while i'm driving and play them back on my computer.
For $100, it's not much more expensive than a scan tool alone.
Supposedly upgradeable to OBD-2, but since I have a 93 I'm not in a hurry.
I'll post to this thread when I get the upgrade (maybe in 5-6 years?)
6th Gear
Joined: Apr 2011
Posts: 6
Likes: 0
Yes , they used the obd2 plug getting set for 95 but its still obd1 so there are empty spaces (but count them). could have moisture in the distributor, welcome to the world of optispark
. codes should point you in the right direction. make sure to check your wire connections.
Go to Corvette Central site and find there C4 Diagnostic Trouble Codes
to get the right codes for your '94. It will show the plug too. Let me know how it goes
If you do need to replace your Opti (lets hope not!) I got mine from Chandler Motorsports Inc. You can find them on Ebay. It was $180.00 with a lifetime warranty,shipped in 3 days,works great! and much cheaper than the big names. Doesn't make it any easier to replace though...
Nanook71 is online now Report Post Edit/Delete Message
. codes should point you in the right direction. make sure to check your wire connections. Go to Corvette Central site and find there C4 Diagnostic Trouble Codes
to get the right codes for your '94. It will show the plug too. Let me know how it goes
If you do need to replace your Opti (lets hope not!) I got mine from Chandler Motorsports Inc. You can find them on Ebay. It was $180.00 with a lifetime warranty,shipped in 3 days,works great! and much cheaper than the big names. Doesn't make it any easier to replace though...
Nanook71 is online now Report Post Edit/Delete Message
Have not had a chance to check out the codes yet. My car is currently stored in Nor CA and should get up there in a week or 2. I went to the Chandler Motor sports web sites and noticed that they sell caps and rotors for the optispark. Are the GM optispark units serviceable? If they can be taken apart to replace cap and rotor, one would think that they could also be dried out if moisture is present. I was also able to get ahold of a factory manual so if you need a list of the codes let me know and I can E-mail you one.
Jim
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Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
But just wondering if they show the CCM, EBTCM and SIR modules. The on board diagnostics will show the codes for all these other modules.
Racer
Joined: Jan 2007
Posts: 252
Likes: 5
From: bethlehem PA
great buy
I too am clueless 
but rather than take a sensible approach and ask someonenlike you did, I just ordered a PC cable from ALDLCable for about $50 TT&L and downloaded some free software. I haven't gotton the cable yet but I’ll repost if it works. (
I’ll be to embarrassed if it doesn’t.)
FYI: The site has the cable, PC requirements and links to software. It might be worth checking out.
Anyone have any experience with this approach?
…And please no jokes about it not supporting the ’65. I know I need the OBD0 for that one. It’s just that they are SO hard to find.
but rather than take a sensible approach and ask someonenlike you did, I just ordered a PC cable from ALDLCable for about $50 TT&L and downloaded some free software. I haven't gotton the cable yet but I’ll repost if it works. ( I’ll be to embarrassed if it doesn’t.)FYI: The site has the cable, PC requirements and links to software. It might be worth checking out.
Anyone have any experience with this approach?
…And please no jokes about it not supporting the ’65. I know I need the OBD0 for that one. It’s just that they are SO hard to find.
8th Gear
Joined: Aug 2012
Posts: 8
Likes: 0
From: West Monroe Louisiana
The paper clip will give you the codes, but if comes up like my '94 that had a rough idle, you may need more. I didn't have any codes and the car passed emissions, but had a rough idle. I have a Actron CP9190 code scanner that does ODBI and ODBII cars and also displays real time information from the PCM while the car is running. Using the scanner I could see the Long Term Fuel trim at idle was showing that there was excess air. I started looking for vacuum leaks and found two. The check valve that supplies vacuum to the A/C controls and the cruise control was leaking. Also the EGR valve was bad, carbon had built up to where it wouldn't close completely. The scanners with the ability to display real time data are invaluable for troubleshooting the FI cars.
Race Director
Joined: Jan 2002
Posts: 12,261
Likes: 85
From: O'Fallon Missouri
Advanced
Joined: Nov 2012
Posts: 62
Likes: 1
From: Amarillo Tx
So Tru. I am one of the new ones. This forum as taught me so much.. I did the paper clip works great for reading codes.. I found it on the forum somewhere.. Also cleared codes, A couple days driving same code. I will be cleaning maf sensor soon.lol
Le Mans Master
Joined: Jun 2009
Posts: 6,528
Likes: 752
From: South Dakota
Similar thread below. I posted the method for reading and clearing codes. I used it on my '94 and it works fine.
Good luck.
http://forums.corvetteforum.com/c4-g...post1582734428
Good luck.
http://forums.corvetteforum.com/c4-g...post1582734428
Advanced
Joined: Nov 2012
Posts: 62
Likes: 1
From: Amarillo Tx
Similar thread below. I posted the method for reading and clearing codes. I used it on my '94 and it works fine.
Good luck.
http://forums.corvetteforum.com/c4-g...post1582734428
Good luck.
http://forums.corvetteforum.com/c4-g...post1582734428
Le Mans Master
Joined: Oct 2004
Posts: 7,706
Likes: 485
From: Everett WA
C4 of Year Finalist (appearance mods) 2019