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Installed a new alternator and I did not unhook the battery.

The starter wire touched something...
Installed a new alternator and I did not unhook the battery. The starter wire touched something and sparked. Now my truck will not start, the lights will not come on interior or exterior, the auto locks will not work, the lift gate will not open. I replaced the mega fuse and the same problems exist. I'm don't even know where to start to look. It's a 2007 yukon Denali.
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Answered in 5 minutes by:
3/22/2017
Amedee
Amedee, GMC Technician
Category: GMC
Satisfied Customers: 27,306
Experience: ASE Technician advanced level specialist
Verified

Hello and welcome!

My name isCustomerand I can assist you with your question.

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I will try my best to answer all of your questions.

However, before we get started, please let me mention a few things.

1. If at any point you would like to speak on the phone, please feel free to request a phone call on your end and I can call you right away.

2. If you dont understand any technical terms or anything that I mention (component tests or theory or operation), please let me know and I will provide you with a more in debt explanation or answer.

3. Please understand that I am here to help you anyway I can.

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Was it the BIG wire that went to the alternator that got shorted out?

Can I start by getting your VIN?

Thank you!

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Customer reply replied 11 months ago
it was the big wire/hot wireVin# *****

It says invalid VIN?

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Customer reply replied 11 months ago
1GKFK63897J297982

Thank you for that information.

Does that big wire going to the alternator have voltage on it now with the mega fuse replaced?

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Customer reply replied 11 months ago
I tested it with a meter and it has fire.

Ok, have you checked the other fuses? I have a feeling there may be more blown fuses.

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Customer reply replied 11 months ago
I have checked all the fuses related to what's not working and none of them are blown. At least visually there not.

Ok, lets dignose this no start issue.

Does the engine crank over and not start or does it not crank over at all?

Have you checked for codes in the computer?

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Customer reply replied 11 months ago
The engine will not turnover. The only I see is the stabilitrack not on.

You need to check for codes in the computer and the operation of the ECM and BCM. Both are needed for the starting circuit to work properly. The ignition switch sends a signal to the BCM, the BCM sends a signal to the ECM, then the ECM activates the starter relay. From there, the contacts inside close and power is sent down to the starter motor. So, somewhere along the line, the starting circuit is not working properly. It is going to be in the ECM or BCM. You just need to figure out which one. This is done by checking for codes and communicating with BOTH modules to see which one is providing you with the necessary data. Chances are one of these modules will not communicate with your scanner or code reader. That will be the module that is either bad or not powered up for some reason preventing the engine from starting.

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Customer reply replied 11 months ago
Why didn't the mega fuse blow preventing any damage to the ECM and BCM?

We dont even know if the ECM or BCM are at fault yet.

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Customer reply replied 11 months ago
Ok, I'll be In touch after I get the codes read.

You should have all of the information now you need to diagnose the condition.. or at least be headed in the right direction. No need to let me know, unless of course you still need help, feel free to reply back.

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I am glad I can help!

It has been a pleasure working with you. Please dont forget to honor your good faith deposit by rating my answer as "5 STAR SERVICE" for assisting you today.

Keep in mind, we can still continue this conversation at no further cost to you even after you rate my answer. Just reply back to me using this page and I will get it and get back to you ASAP!

Also, if you are a member or if you have a subscription to the site, you still need to rate my answer in order for me to get credit for assisting you with your question.

Please let me know if you have any further questions.

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Hello there!

I am just checking in to see how things are going and to see if you need any further assistance?

If so, please let me know as I will be happy to help.

Best Regards,

Customer/p>

Amedee
Amedee, GMC Technician
Category: GMC
Satisfied Customers: 27,306
Experience: ASE Technician advanced level specialist
Verified
Amedee and 87 other GMC Specialists are ready to help you
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Customer reply replied 11 months ago
I checked the codes and this is what is flaxhing in red = CAT, EVA, O2S, and HTR. It also has the message NO POWERTRAIN DTCS OR FREEZE FRAME DATA IS PRESENTLY STORED IN TGE VEHICLE COMPUTER.

Thank you for that information. What exactly is your question?

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Customer reply replied 11 months ago
This is from the previous conversation we had concerning the arching of the alternator wire during an install. Now the vehicle will not crank, no interior lights, auto locks don't work, lift gate and a host of other issues. See previous conversation!

Thank you for clearing that up for me?

Would you be willing to speak on the phone?

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Please accept my offer and call me

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