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LT1 Computer problems " No response but car runs"??


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I have a 95 LT1, it runs, but when I try to read the computer with my edit software I get a no computer response, I attached my scan tool and it can't get a response.

I have checked all hot and ground wires, they are fine. I have checked the wires to the data link connecter and they are fine.

The service engine soon light is always on.

 

And I have left the computer with out power and it don't help. The service engine soon light comes on instantly.

 

The first time I noticed I had a problem I hooked up my Edit program and uploaded the pcm file, after that no more responses.

 

I have checked a lot of wires and find nothing wrong. It was working fine. All I have done is added is a fan relay and I unhooked it with no help..

 

Anyone ever have a problem like this or any ideas what I should do next??

 

Thanks..

 

Terry

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I had that problem too, it ended up being a problem with the port setings on my computer vs. the port settings in Tuner Cat.

 

What kind of wire are you using to edit? I have a USB to serial port adapter. I had to install extra software for the cable to work correctly(it was supplied by the maker of the cable set up).

 

Guy

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Guy,

 

Your advice has helped me out several times...

 

The whole problem is odd. I have uploaded and downloaded several times.

 

The car had been sitting for a while and I had just finished up a few lose ends and wanted get in and get the speedo set right.

I first downloaded the .bin file, did one small change and tried to upload it. I get a no computer response return. I have a scan tool that I have used on the car in the past also just checking things out and it comes back no computer response also. It tells me to check the plug connection.

The S.E.S light is on all the time. Even after I un hook the battery.. This I don't think is normal; it should be off after resetting it. Than come on as new errors are reported.

Any advice is appreciated.

Terry

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If the computer is dead, the motor won't run.... I would have to agree that the likely suspect is a loose wire in the ALDL. Maybe after you downloaded, you pulled the cable out of the ALDL and pulled something loose.

Do you have a friend with an LT1 car close to you? Call in a favor and plug your computer in their car and see if you can read it.

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You need three wires to the DLC:

1: D30 (serial data) goes to "M" on the DLC

2: D20 goes to "B" on the DLC

3: "A" on the DLC goes to chassis ground

 

 

First thing I would do is check your ground wire on your DLC, the "A pin". I wouldnt worry about your PCM being dead since the car runs.

 

DLC.gif

 

Your using the 12 pin OBDI connector correct?

 

Guy

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Well, I have the 16 pin connector.

I did check all the wires from the plug to the PCM, the ground and hot..

They all checked out fine for continuity and voltage. If its the general option that I have a bad connection, which would not surprise me I had one on the Alternator plug that I think cost me $55 for a rebuilt Alt..

 

I will check the wires again, does anyone think I could have problems like this if I have a pinched or grounded wire from the PCM to some other motor component??

 

I will post what I find, maybe help someone else someday..

 

:)

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