StealthLT4

Hopefully someone can help with this. My OBDII port doesn't work. It has power and ground going to the plug (checked pin 4 to 16, or whatever it is, and it was 12v), and ALSO my handheld OBDII code reader works fine.

However, LT1 Edit cannot connect to the car to read the ECU, and the same problem is there for AutoTap (datalogging software). I took it to the dealer, and all they can tell me without taking it in for $100/hr is that the plug is getting power, but not communicating.

I sent the LT1 Edit cable back to Carputing for analysis and troubleshot with them for about 2 weeks trying to figure this out. Once I got AutoTap and it did the same thing, I have to assume it's the car.

It's either the ECU or the OBDII plug, and I have no idea which. I took a close look a the plug and nothing looks out of the ordinary. The previous owner did a PCM4less tune (I think that's what he used); does that replace the stock ECU? Could it be the problem?

Thanks...I hope...

JAKE

Have you tried a paper clip or a jumper wire between 12 and 4 on the under dash link? I do that when checking for SES codes on my 96 and also on my son's 96. Any codes show up on the dash.

Doing that would, at least, tell whether there's communication going on or not.

Jake

StealthLT4

I think that would work since the handheld scanner works. Also, data doesn't actually flow out of the OBDII port when you do the paperclip method; that just means that those 2 wires of the connector work, and the computer can communicate with the console. It's like my problem is with the actual data output of the OBDII port, but the DTC wire still works fine.

tdr1919

have you looked over on the scan & tune section? most likely your ODBII output from your car is fine, rarely is the data output is bad.
It maybe your PC is not detecting the levels from the odbII
I take it your cable connects to your USB port? if that is the case some USB to serial cables cannot detect the OBDII output.

psd_bullitt

Is this on your LT4? I didn't know the LT1Edit would work with the LT4.

StealthLT4

Yes, LT1 Edit comes in an OBDII version for 96-97 Corvettes and F-bodies.

As for the cable, it's a direct USB interface, and I even sent the cable back to Carputing to verify its functionality. I also sent them the communication logs from my failed attempts at reading the ECU, where the interface module (box that converts the OBDII cable to USB) says its getting bad data from the ECU, so it's external to my laptop, which we also diagnosed.

One thing I just through of is to try out using the AutoTap cable/software on another car just to make sure it's not my laptop. However, that wouldn't explain the GM scanner not connecting at the dealership ... something is funky with the connector or the ECU.

Zix

This may sound odd, but are you trying this with the driver door open or closed? If you've been keeping it open, close it and see if the computer will communicate...

toptechx6

This may be a long shot but I'll toss it out there. You may want to check the part number of the PCM, some guys switched back to the OBDI controller on 96 cars because tuning software was less expensive, see this link for an example.

http://www.madtuner.com/index.php?pa...mart&Itemid=26 good luck sorting it out.

BrianCunningham

contact PCM4less and see what they have to say.

Did he change the chip? or just have it reflashed?

StealthLT4

Drivers door is always closed, though I've tried it both ways and it doesn't affect anything.

I'll check the PCM and call PCM4less.

Here's the really weird thing (sorry forgot to mention this first); LT1 Edit successfully pulled the .LT1 file 3 times when I first got it. However, the connection was flaky, and it took me several attempts to get a successful one each time. Now it just plain won't work, just like it was doing before, but it never succeeds.

TravisD

Sort of sounding like there may be a loose pin on the connector or something....

merim123

i'm curious if you found a solution to this? I'm getting the same issue with my 96 camaro and lt1 edit and autotap as well. I can't get anything to communicate. I was able to read the .bin initially, but now can't anymore. Not sure what's going on. Leaving the key in the on position too. One thing that worked for me was just letting it keep trying over and over. It did connect after about 30 minutes, but don't feel that it should do that. I am using a USB to rs232 adapter and not sure if that's a problem or not. Use to work really fast on my old laptop that actually had a com port off of it. I wonder if there are specific settings we should have for the COM port?

pcolt94

Suggestion:

There have been many issues using the USB interface. I know that many of the newer computers of today do not have the RS232 serial connection. There is a lot written in the scan & tune section of the Forum on USB. There is some people who are using it with no problem. You might have to get a cheep older laptop to run your application. There is a lot to choose from on Ebay.

The clue here is your OBD2 reader works fine which means the data is probably OK. Interface problems can be tricky. They can flip flop back and forth with the input data. You even indicated it took a few tries to get the down load which might indicate a USB interface problem.

StealthLT4

I'm using a straight OBDII-to-USB cable, so no RS232 interface issues. I sent the cable back to Carputing (makers of LT1_Edit) and they checked it out and it's fine. So unless my brand new laptop has a problem with the USB port where every other device works, it's the car. Also, when the techs at the dealership connected their scan tool, they couldn't get a signal either.

I've pretty much broken down and admitted I'm going to have to get the dealer to figure it out, just waiting til I have enough money (moving is expensive...)

merim123

i ordered a pcmcia rs-232 adapter card. I'll let you guys know how it works out.

pcolt94

Good luck at the dealer when it comes to electronics especially data communications, usually they have one guy that may have a clue. Not saying don’t go but before you do, try these ideas first.

* Find a friend and see if they have a Tech1 or 2 and see it they can communicate with your car.
*Try your computer on another car, more than one would be nice.
* Reseat any plugs or connectors you can do or get to with the CCM.

pcolt94

If your saying that your scanner is one of those basic OBD2 code readers and it works OK, wouldn't that mean that you have communication with the CCM and PCM. If this is true, it would seem like the car is communicating to the outside world.

StealthLT4

That's what you'd think, but that would make too much sense. The basic scanner works, but the GM Tech 2 and my USB interface (both LT1 Edit and AutoTap) both won't connect.

theadmiral94

StealthLT4,

Might you be making a bad assumption -- is it possible that the Dealer 'mechanic' either miss-reported his result or connected or configured his 'tech-?' device incorrectly or had a faulty 'tech-?' device?

Reason: the code reader should receive data on the same connections as a 'tech-2' and in therory the 'DLC to USB OBDII' adapter. So, if your code reader is able to read, then the CCM is transmitting the information and the dealer's 'tech-?' should have also been able to read.

Admittedly there is also the need to talk to the CCM, so have you tried using your code reader to 'erase' the codes and does it work?

If so, then that would suggest the problem lies elsewhere and that likely you cannot depend on the Dealer's information in determining the problem as the mechanic info is unreliable.

Given that, as a reminder, there is a recent great post on the 96s and what can/cannot be done with them (codes wise), and one important point is that the PCM does not report info via the diagnostic function which reports other 'module' information.

Given that yours is a LT4, there could be some unique GM 'features' (i.e. oops or didn't quite make it work correctly), but nonetheless, since it worked with your old computer/other program, I would suggest its likely something about your laptop.

One likely problem could be that since USB ports run at the speed of the 'motherboard', likely your new computer has a faster 'motherboard' than the older one, which means the USB port is faster and could be running too fast to properly sense the much slower OBDII transmission rate. Another issue could be if the new computer is a USB 2.0 port versus 1.1 or 1.0.

Unfortunately, unlike COM ports which do have speed/rate/parity/etc parameters, USB ports don't. So, the program running must slow down the USB port, which may not be designed to do so.

SO, with the other member which suggested grabbing an older computer which has an old fashion 'serial' port and seeing it the car comunicates to it. If so, you now know its the computer and can work to resolve it.

merim123

I got a PCMCIA card (with 2 RS/232 ports) for the exact reason of not being able to control the speed via USB. That came in the mail today and after fussing with the drivers for a bit, i was ready to try again.

After realizing I had one bad serial cable I was ready to go. Tried connecting and basically the same issues:

1) lt1edit- keeps timing out trying to read
2) autotap cannot detect the car
3) scan gauge - keeps just showing 'connecting...' on the screen

I don't know if I'd spend the money on the dealer yet, I may get a used PCM and try it, it's possible something happened to the PCM, but I'd really like to confirm first before spending money.