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Gary, Chevy Technician
Category: Chevy
Satisfied Customers: 16852
Experience:  15 years GM master tech
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I just replaced my ECM and need to have my keys relearned for

Customer Question

I just replaced my ECM and need to have my keys relearned for the VTD. The instructions indicate to perform (3) 10 minute cycles of turning the ingintion to the ON position and the SECURITY light will be on for approx 10 minutes and that when the SECURITY light goes off I can move to teh next iteration. My problem is that the SECURITY light is not on when the ignition is in the ON position. I ran through the procudure anyway and my truck will not start. THe starter engages but I suspect there is no fuel getting to the engine.
JA: A security light issue can be an easy fix, once you get all the information you need. Luckily, the mechanic I'm going to connect you with knows all the ins and outs of the issue. Are you hoping to fix this yourself?
Customer: yes
JA: Great! What have you tried so far?
Customer: I have tried the GM VTD Relearn Procedure
JA: Is there anything else important you think the Chevy Mechanic should know about your Chevy?
Customer: no
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Chevy Mechanic about your situation and then connect you two.
Submitted: 1 year ago.
Category: Chevy
Expert:  Juan Crespo replied 1 year ago.
Hi there.What year model GMC truck are you working on?
Customer: replied 1 year ago.
chevy 2002 silverado, it is a diesel
Customer: replied 1 year ago.
I am going to re-run the procedure to relearn the key code that was provided. That takes approx 30 minutes (10 minutes for each iteration). I will monitor for your response...
Expert:  Juan Crespo replied 1 year ago.
Hi there.Before we begin, please understand that all I can do from where I am is offer you my technical knowledge and guidance. It will be up to you to provide the equipment and tools needed to diagnose and repair your vehicle.Based on the symptoms you describe, it looks like there is a problem with lack of serial data communications between the BCM, Cluster and PCM - if the circuit is down, the Security Light will not come come on and the engine won't start.Was the new module programmed to the truck's VIN? Do you have access to a scan tool that can communicate with the BCM?
Customer: replied 1 year ago.
I do not have a scan tool. Yes, the module was programmed with the VIN. I provided that to the seller of the device, so I can only assume that it was done properly.Are there any other symptoms cor a lack of serial communications?
Customer: replied 1 year ago.
Here is some more detail: when I open the door and there is no key in the ignition, the SECURITY message flashes. When I put the key in then turn to the first position, the SECURITY message changes to a red battery indicator and that is what remains until I return the key to the position where I can remove it. Would the SECURITY message work like this is there was a communications problem?
Customer: replied 1 year ago.
I have just confirmed the VIN I sent the seller is the proper VIN for my truck.
Expert:  Juan Crespo replied 1 year ago.
Based on that information, it sounds like the issue might be with the security system itself. Problem is that a Tech 2 or equivalent scan tool is the only thing that'll communicate with these modules so we could find out what the problem is.At this point it has become clear that I won't be able to help you, therefore I'll opt out so others may try. Please do not reply until another expert responds or the site will send you right back to me.Good Luck.
Expert:  Gary replied 1 year ago.
new expert here may i ask why the computer was replaced ?if you plug back in the old computer will the truck run ?