Help! Scanner will not read computer

[Lahodny]

My 1995 Corvette has been stumbling badly first thing after starting. Will eventually smooth out. Plugs/Wires/etc done. Fourth fuel pump installed. Took it to Big O today, and they said that their scanner could not establish communication with the car's computer. Also, I did tune it with a Hypertech Tuner, but returned it to stock settings before taking it in for service. Any ideas?

 

[toptechx6]

I'm guessing "Big O" is a local parts store and they likely tried to scan it with an OBDII scan tool. 94 & 95 Corvettes use a scan tool (ALDL) connector that appears identical to the OBDII connector used on 96 and newer cars, but 94 & 95 are in fact OBDI.
There are a few inexpensive scan tools such as Autoxray that will read the data stream as well as professional grade tools such as Tech1 and Tech2.
If you just want to retrieve codes you can do that yourself using a paperclip, see this link.

DigitalCorvettes.com - Corvette Forum

 

[Bronze85]

A snap on scan tool with GM-1 connector will also work using legacy software etc.

 

[gmjunkie]

A snap on scan tool with GM-1 connector will also work using legacy software etc.

No, Snap-on GM-1 connector will not work on 94,95,or 96 Corvette!:W:W:W

94,95,96 will require OBDII (B) connector with K-9 personalty Chip!

 

[Bronze85]

:bashNews to me, I thought 96 vehicles and up were OBD II

 

[Hib Halverson]

All 1996 Corvettes are OBD 2

1994 and 1995 Vettes are a sort of hybrid of both OBD and OBD2. The Corvette, the Camaro, the S/T-trucks and a few others were part of GM's early roll-out of OBD2 and had parts, but not all of GM's OBD2 hardware and software.

As far as reading serial data and getting the codes that turn on the engine light, you need a scanner that supports the the model year in question but also has the hardware which connects to a 16-pin "OBD2 style) DLC connector.

It's possible that the scan tester "Big O" used was an OBD2 tester.

 

[93Rubie]

Pending your problem is just not using the correct scan tool, there is one other possibility. If you use a scan tool that should be able to talk to your Corvette and still cannot. You may have a communication problem.
IF that be the case, but I suspect not, you need to start doing the following.
First of all you will need to determine (FSM) what modules you have and make sure they all have power and ground. It may have what is called a gateway module, that all the other modules talk through it, to talk to the scan tool. I think in my 93 it is the CCM but I cannot remember right now. This is the one you need to make sure has power and ground to start with. IF they do and you still cannot communicate with them, get out your FSM and start tracking down the comm. wires between the modules. Make sure they are all intact and do resistance checks to make sure.

I had a comm. problem with the APIM (Accessory Protocol Interface Module, its really sad I remember this off the top of my head) in a 2010 Mustang GT (had a Roush Stage 3 package, very nice). The SYNC system (contained with in the APIM) did not work, no codes, no nothing. I did a self test of just that module which woke it up and it started working properly. Its like it went to sleep and when I pinged it, the module woke up. Weird one but hey I fixed it!!!

Probably more info than you needed but it never hurts to know.
And remember communication problems are FUN to figure out!!!