Unhooked Battery, now it won't start- Please help! *SOLVED*

[George B]

So make it 13 minutes between off/on/start cycles. Or maybe try in succession the procedures documented in the first 19 YouTube videos that address similar problems.

Without a high end two way scan tool, it is going to be a kind of blind man’s bluff thing.

It is possible it isn’t even a theft deterrent problem. It could be a fried liftgate control module, BCM, PCM, crank relay, etc. etc. etc.

Building on this logic: I wonder if the liftgate module shorted and is pulling the comms bus down.
Without a two way scan tool, oscilloscope and wiring diagram this will be hard to find. Work your way upstream from the liftgate motor.

 

[wsteele]

Building on this logic: I wonder if the liftgate module shorted and is pulling the comms bus down.
Without a two way scan tool, oscilloscope and wiring diagram this will be hard to find. Work your way upstream from the liftgate motor.

I agree. The lift gate logic is tied into the whole "do we let him start this thing up" code. It might be something as simple as resetting that module (or the BCM) so it says everything is jake with the lift gate...

A Tech 2 would be invaluable in this circumstance.

Edit: Maybe check the thread below out and see if one of us that own a Tech 2 is nearby. A long shot, certainly, but not any more of a long shot than doing many of the YouTube procedures guys document to get their no start trucks back online.

Tech 2 Owners Map

There are quite a few members that have a Tech 2 and there are always people who wish they had one to use so I thought I would post this thread to try and help each other out. If you own a Tech 2 and would be willing to help out another forum member that might be local to you then post up your...

www.tahoeyukonforum.com

 

[Scrapman]

Building on this logic: I wonder if the liftgate module shorted and is pulling the comms bus down.
Without a two way scan tool, oscilloscope and wiring diagram this will be hard to find. Work your way upstream from the liftgate motor.

Do you think unplugging the liftgate module might let it crank? Or possibly re-set something?

I was replacing the latch assembly with the battery connected because every video I watched on how to replace it never mentioned unhooking the battery. It seemed like a simple plug and play. When the assembly started whirring when I plugged it in, I unplugged it and then unhooked the negative battery cable.

Finished installing the latch, hooked up the battery and got the no start situation I'm in.

 

[George B]

Do you think unplugging the liftgate module might let it crank? Or possibly re-set something?

I was replacing the latch assembly with the battery connected because every video I watched on how to replace it never mentioned unhooking the battery. It seemed like a simple plug and play. When the assembly started whirring when I plugged it in, I unplugged it and then unhooked the negative battery cable.

Finished installing the latch, hooked up the battery and got the no start situation I'm in.

Yes, undo whatever you did and see what happens.

 

[wsteele]

What it has sounded like from the beginning is when you connected the actuator and it was running, you disconnected power and the state the module that was calling for the lift gate actuator to run was left in that state. That state may be incompatible with starting the truck, TD or otherwise. If you can clear that state (may be as simple as disconnecting things that are lift gate related and reconnecting), you may get back the privilege to start the truck.

 

[wsteele]

Another thing to try would be if you have a liftgate switch on your console , flip that switch off, maybe the PCM won’t check the liftgate status with it off.

 

[89Suburban]

Plug the old one back in? Isn’t the positive terminal usually the one that gets disconnected?

 

[Scrapman]

What it has sounded like from the beginning is when you connected the actuator and it was running, you disconnected power and the state the module that was calling for the lift gate actuator to run was left in that state. That state may be incompatible with starting the truck, TD or otherwise. If you can clear that state (may be as simple as disconnecting things that are lift gate related and reconnecting), you may get back the privilege to start the truck.

Yep. I just don't know how to clear it. I have taken the new actuator back off, re-installed the old one; Tried to crank- Nothing

I also stuck my hand through the opening for the jack and unplugged 2 of the 3 wire looms going to the liftgate module. (I couldn't figure out how to get the bottom one unplugged) and still no change. I may try to get the last one unplugged again.

 

[Scrapman]

Plug the old one back in? Isn’t the positive terminal usually the one that gets disconnected?

I could be wrong, but I was always taught that DC current in a vehicle flows from - to +, and to take the - off to work on anything. I wish I would have heeded that lesson before installing the latch.

I also put the old one back in and it didn't change anything. Thanks for the idea.

 

[wsteele]

I believe people are told to disconnect the negative to reduce the chance of sparks, shorts, etc. while disconnecting.

From a DC theory point of view, you need both sides to make a circuit.

Do you have a liftgate power switch on the console? And if so, have you tried turning it off?

 

[89Suburban]

Is this the actuator for the lock or is is a power lift motor?

 

[Scrapman]

I believe people are told to disconnect the negative to reduce the chance of sparks, shorts, etc. while disconnecting.

From a DC theory point of view, you need both sides to make a circuit.

Do you have a liftgate power switch on the console? And if so, have you tried turning it off?

Yes, I have a liftgate switch on the console. Doesn't seem to make a difference when I turn it off.

I am at wits end. I have always worked on my own cars but this one has me stumped. I have checked all fuses, under hood and in the cab, and traced down all the grounds I can find.

I have been hesitating trying the "relearn the key process" since the security light is not on; because I'm scared I might make the problem worse.

 

[CaptainAmerica1]

I’m only 2 hrs from you but I have family in town or I’d make the trek to you with my tech2… most days I’m just watching tv and drinking beer anyway. If you don’t have it fixed by next week maybe I can head that way…sorry I can’t get there sooner buddy.

 

[Scrapman]

Is this the actuator for the lock or is is a power lift motor?

The actuator for the lock is what I was originally changing. When I plugged in the new one, it started whirring, so I unplugged it and unhooked the negative off the battery.(That was yesterday)

A moment ago I unplugged the three wire looms that plug into the liftgate module (that is above the drivers side fenderwell below the jack), but it didn't help.

 

[Scrapman]

I’m only 2 hrs from you but I have family in town or I’d make the trek to you with my tech2… most days I’m just watching tv and drinking beer anyway. If you don’t have it fixed by next week maybe I can head that way…sorry I can’t get there sooner buddy.

Wow. That is very nice. Hopefully I can figure it out before then.

Thanks

 

[89Suburban]

What it has sounded like from the beginning is when you connected the actuator and it was running, you disconnected power and the state the module that was calling for the lift gate actuator to run was left in that state. That state may be incompatible with starting the truck, TD or otherwise. If you can clear that state (may be as simple as disconnecting things that are lift gate related and reconnecting), you may get back the privilege to start the truck.

Where is the harness connector for the gate? Maybe if he unplugs that?

 

[CaptainAmerica1]

Wow. That is very nice. Hopefully I can figure it out before then.

Thanks

I’m a field service engineer so it’s what I do. Fly all over the country and repair industrial automation equipment.. just another day for me….

 

[wsteele]

Where is the harness connector for the gate? Maybe if he unplugs that?

I believe it is right at the lift gate motor (the control module is on top of the motor, I think, and the harness plugs into the module right there).

It really seems like he is going to need a Tech 2 (or other professional scan tool) to get it sorted.

 

[Scrapman]

I stumbled on this thread on a Silverado forum and the poster unhooked only his negative battery cable and he was having the exact same symptoms as me.

So to start I have a 2007 Silverado Z71 4x4 w/5.3L

Disconnected the negative cable to hopefully reset the TPMS because I rotated the tires and trying to do the re-learn and it would not do it. So I disconnect negative cable ONLY. Go into the house and eat lunch. Come back out and hook negative cable back up.

Put key in Ignition turn key to on position and nothing but the engine light on. A second later It starts 6 chimes and then the dash lights up. Stabilitrak off, Traction Control off, Service 4x4 system, and service Tire Pressure Monitoring system error code keep flashing and cycling through on the dash. The Padlock (theft deterrent I assume) does come on but goes out after like 10 seconds

I have no door locks, power windows, wipers except on high. Headlights only work with key on and low beams only. HVAC and Radio work fine. EXCEPT radio on XM displays XM Theftlocked. My key fobs do nothing either. And EVERYTHING worked just fine prior to this. I have NEVER had an issue with this truck.

I have tried everything that I found on Google. Disconnected the batteries again. Cleaned the Ground wires. Still doing the same thing.

I was able to hook up a Snap-On Solus Edge and am getting error codes for all those things above but also it is telling me that it has no communication with the BCM U0140, U0100, U0101 codes. I was also able to get in there and see that the key Fobs were working in the Solaris scan tool.

I am trying to eliminate having it towed to the dealer. Has anyone else had this issue, where to start next and if so any help would be GREATLY appreciated.

I took a Video of what the instrument cluster is doing and will post that as soon as I can get it off my phone.

Thanks for your time.
Original PostercdirkNewbie

He finally took it to a mechanic that was able to reprogram the BCM and it fired up.

So I spoke to the Mechanic from the dealership working on my truck today. He wanted to talk about the issues and get my story. So I went through everything with him together and just to be on the same page. So a few hours later of him troubleshooting it he was able to reprogram the BCM and it fired right up. The crazy thing was he asked me if it was a different or new BCM. I told him that it was the original BCM, 11 years old and 110,000 miles on my girl. Evedentally it lost all data but he was able to get it back to life. They are keeping it over night to double check it in the morning. So crossing my fingers I get to bring my girl home tomorrow.

Is reprogramming the BCM the same as the steps for learning a new key?

Here is the thread:

No Start Issue 2007 Silverado : Electrical

Possible Theft deterrent activated - So to start I have a 2007 Silverado Z71 4x4 w/5.3L Disconnected the negative cable to hopefully reset the TPMS because I rotated the tires ...

www.silveradosierra.com

 

[George B]

Interesting