Hi all...

I forgot to connect my battery tender and ended up with a dead battery. I had no problem replacing the battery, but now, the key fob will only open the hatch. Neither door will unlock.The car is a 2015 C7.

Pressing the unlock button on the fob, I hear a click that sounds like a solenoid or relay, but the doors won't unlock. And if I attempt to open the doors normally, when I press the door unlock switch, I just get a series of similar clicks.

Any ideas?

 

Disconnect the negative battery cable for a few minutes to reset computers and try again.

If that doesn't do it, verify that the 3 fuses in use on top of the battery are still good. Should have 12 v on each side of each fuse.

 

Will do. Thanks so much! :-)

 

Same thing happen to my 2014 when my battery went out. This fixed my problem also.....Robert

 

Loose battery connection. Look closely at the + lead. It must sit absolutely in the correct alignment when you tighten it down. If it is the slight bit crooked, you will have issues.



Elmer

 

The problem persists, but I found the problem.

While I had the negative terminal off, I re-connected the positive terminal, making double-sure it was seated properly. I reconnected the negative terminal and checked voltages. All checked out normally, EXCEPT the load side of the 350 amp fuse. It's blown...

Thanks again for the help, friends. :-)

 

You may be hearing the fuel door lock solenoid when you push an unlock button. This should be electrically separate from the door locks. At least the fob system works.

Obviously without the 350 amp fuse the car won't start. But - you may be able to get into service mode and be able to release the parking brake, turn the steering wheel, and get out of park (if an A8). Try holding the start button for about 10 sec without your foot on the brake (or foot on the clutch). All systems should come on except the engine. Do what you need to do and push the start button again to shut down. There is not a system time out in service mode.

It's unclear from what you said if you accidentally touched + to ground and popped the fuse or if there is a fault. I believe the 350 amp fuse goes to the starter, possible through a fusible link located somewhere near the front fuse block. Don't know if the 350 fuse is a dealer part or if any auto parts store has them. If you could get a fuse, I would disconnect the negative battery cable, replace the fuse, and give it one more try.

Let us know how this gets resolved.

Good luck!

Ron

 

Thanks for the info, Ron.

There may be a fault with the starter or solenoid. When I installed the new battery, I connected everything to the positive side first. Then, when I connected the the negative terminal, there was a HUGE spark! Typically, since there's little load on the electrical system, there'll be a small spark, but that big spark indicates there was some kind of high load on the battery.

I think I'll try your procedure to unlock the steering/parking brake/etc and tow the car the to the dealer. Blowing a 350 amp fuse does not give me a warm fuzzy and, at the very least, if there's short in the starter or solenoid, I'll just immediately blow another 350 amp fuse and the 40 bucks for the cost of the fuse.

 

Yeah, sounds like an electrical fault. The fuse protected you from additional damage. I just replaced my battery a month ago (4yr old) because all of these battery threads were making me question the battery even though I had no symptoms. I don't recall any spark when I connected the negative cable.

Bummer....

 

That tiny little tidbit of information might have gotten you a quicker answer to check the 300amp fuse.


I'm glad you found the issue but I wonder why the fuse blew. Did the neg cable touch something it shouldn't have?

Elmer

 

He says the big spark was when he connected the negative cable (and completed the circuit). Something downstream of the big fuse was already grounded.

I'm also curious exactly where the fault is and how something went to ground while the battery was dead. He doesn't note doing any work on the car. Maybe rodent damage?

We'll have to wait for an update.

Ron

 

I'm starting to make some sense of this. I now suspect, the fault with starter/solenoid/whatever is what killed the battery in the first place. Just out of curiosity, I measured resistance from ground to the blown open, load side of the 350 amp fuse. It measured ZERO ohms! In other words, somewhere in the starter or starter circuit, there is a DEAD SHORT!

I approached this problem as a routine dead battery swap. It's obviously, just a little more complex than that...

Thanks again for the support! :-)

 

Did you get your car fixed?
What was the problem?
Thanks,

Mike

 

Thank you, Thank You, THANK YOU! Went out this morning and my 2014 wouldn't start. Tried jumping it... nuthin'. Checked with voltmeter. Battery pretty much toast. Bought a new one, installed it... and saw the same results. Plenty of lights on the dash. Everything working. But push the start button and nuthin'. Cursed the Theft Deterrent System repeatedly then found this thread. Went back into the trunk, loosened that &#@%ing red positive cable, tightened it back up... started like new. Took her for a spin, came back, started right up.

Gotta love a happy ending. Thanks again!