Hi! I have a 1994 z28 camaro that has many issues. Previously I have searched forums and have done lots of googling to repair it as much as I can, but I am tired of not being able to pinpoint my troubles with the car. I want to diagnose its problems more efficiently, which brings me to my current situation. I am extremely new to using scanning software's and am by no means adept with working on vehicles, so I may be making easy, rookie mistakes.


I recently bought an ALDL cable from Red River and downloaded two scanning software's: scan9495 and TunerPro RT. I followed the necessary instructions on installing and getting the software's to run on my laptop. I went on to my final step of plugging my cable into my OBD port and began scanning with the softwares. The scanner reads the car because I can see data streaming into my laptop and as a test, I revved it to check and see that the data was reading and sure enough the engine speed jumped up with the rev! So far so good!


PROBLEM: My issue is that when I try to read the DTCs for the car there are no error codes showing up?? Initially, I tried using TunerPro RT then I switched to scan9495 to see if it did the same thing, and it did! The car definitely has issues because it reeks of fuel smell from the exhaust and it will have hard shifts occasionally when accelerating. So I know there should be codes popping up... any help will be greatly appreciated!!!

 

No codes found with Tuner Pro or Scan9495. Is the SES light on? Does it light up in “bulb check” when you turn the key to “RUN”?

It's entirely possible for an engine to run poorly without setting a code.

Have you tried something like pulling a sensor connector to force a code? Unhook the MAF sensor or the TPS sensor with the engine running.

 

Thanks for a quick response Fred! The SES light is not on in either "bulb check" and when the car is actually running. The lights that show up on my dash are the security light and ABS. Unfortunately, I cannot have the engine running because recently the car just stopped turning on and only cranks. Suspecting a fuel pump because I don't hear it priming when I turn the key, but I haven't checked the fuel pressure. I was hoping that by fixing the code issue it would help me diagnose the no start situation before I went into anything else.

 

You can test the fuel pump by supplying +12 volts to the fuel pump prime connector near the PCM:

http://shbox.com/1/fuel_pump_prime.jpg

That bypasses the fuel pump relay and should cause the pump to run.

 

Thanks for the advice. Does a bad fuel pump produce an error code though? If so, I would like to fix the no code situation first so I can use it to my advantage!

 

And I am fairly new to working on vehicles, so how do I "supply" volts to the connector?

 

There is no code for a failed fuel pump or a failed relay. On the other hand, low fuel pressure will cause the engine to run lean, and there are codes for that, depending on how lean it gets. There are also codes for the fuel pump enable signal from the PASS-Key II (VATS) security system.

Attach a length of 12-ga wire to the stud in the red battery "+" junction box on the passenger side inner fender. Crimp a 1/4" male spade connector to the other end of the wire, or just try and insert the stripped end of the wire into the connector. As soon at it makes contact, you should hear the pump kick on.

Here's the code list specifically for the 1993-95 LT1 engine:

http://shbox.com/1/Dtcs.htm

Is this vehicle a recent purchase? Sounds like someone may have removed the bulb for the SES light or somehow covered it. Should light up in bulb check. And yes, there is a code for a failed/missing SES light bulb = DTC 11.

 

I've had the vehicle for 2 years about and have been working on it as my project car. I knew little to nothing in the beginning and everything I have learned about vehicles so far has been from working on this car. It sat in my parents backyard for 5 or 6 years before I started messing with it. Prior to that I believe one other owner. I am unaware of anyone messing with the SES light besides myself when I took out my instrument panel and replaced all the bulbs in it because all the bulbs were not lighting up... later found out it was just my dimmer switch was broken and stuck on the lowest dim setting. I believe they should all be good bulbs.
Could the code issue be related to the PCM?

 

Or I guess a better question is, besides the obvious no issues so no codes, what can be related to the car not producing codes?

 

I've been helping people with scanning cars since I bought my Formula brand new in 1994. One of the first accessories I purchased was a device called the “Scanmaster LT1”. It hooked up to the tan data wire in the ADL connector. It displayed in real time about 20 sensor readings and PCM parameters, and all existing codes. Watching that gave me a good insight into how the PCM worked. I supplemented that was reading several detailed manuals and books on GM fuel injection systems.

I put together a 29 page manual with the specific purpose of helping people with how to install the Scanmaster, and how to interpret the data. Here's a link to a thread that accesses a .pdf copy of the manual. This version deletes the Scanmaster hookup details:

https://www.camaroz28.com/forums/com...-guide-886891/

There is also a huge amount of info on the Shoebox website - best LT1 reference on the internet:

4th Gen LT1 F-Body Tech Aids

You can also access and download a free copy of your factory service manual here:

https://www.mediafire.com/?40mfgeoe4ctti

For the specific answer to your question, in the 20+ years I have been helping people on sites like this, I have never run into a problem of not being able to pull codes, when using the correct device/software. Since you are able to see the real time data using Scan9495 you should be able to pull codes. I will caution you that while I understand and can explain the significance of a detailed log of the PCM data, I have never used Scan9495 myself. In 2000 when I had the stroker built, the operation of the engine was turned over to a high end aftermarket engine management system from MoTeC. Not having used Scan9495 I can’t tell you if there is some trick to setting it up to pull codes and initiate 2-way communication that allows you to set codes, clear codes, actuate systems, etc. The author of Scan9495 is a member here, but no longer drops in. I've contacted him in the pat for help with problems like yours, but he hasn’t responded.

Not sure how to tell you to proceed.

 

Thank you for everything so far Fred! I tried the fuel pump prime connector method and I didn't hear the fuel pump come on.

I will see if I can get in contact with Gary Doug about scan9495, and see if he can help with my no code issue! I will also try to message Shbox since he seems to know a lot as well!

 

Did you have any luck contacting GaryDoug?