Author Topic: What an ordeal -- battery change on the 2011 DTS  (Read 3577 times)

Offline goodfellow

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What an ordeal -- battery change on the 2011 DTS
« on: May 26, 2020, 03:08:16 PM »
A pretty easy "looking" job turned into a nightmare this afternoon. My 2011 DTS needed a new battery. The old one was tested in the car with an Altel 539B using the battery test function, and it showed that the battery was marginal (in terms of cold cranking amps). I hooked the battery to a tricklecharger for a day and re-tested; same result -- no go!

Yesterday evening i picked up a new battery with the intent of installing today. Since I didn't want to lose my radio, computer, and module memory settings, I opted for a "hot" swap using a memory minder cable connected to the OBDII port and hooked to an auxiliary 12V battery. This usually works very well and ensures for a good transition between the old and new battery; while keeping the system alive and functioning without problems.

Not today -- I installed the new battery and although the lights, windows, and radio worked fine, the car would not start. Fuel pump relay clicked, but no dash lights or functions available. Thinking I could pull some possible codes, I hooked up the Altel 539B, but it would not connect to the car's diagnostic functions. The thing was totally dead in the water -- so to speak.

I pulled the rear seat and used a 12V test light to check the fuses in the rear fuse box -- all seemed OK. After an hour of frustration, I got out the PowerProbe and tested every fuse in rear fusebox again -- this time the PowerProbe hit the #13 fuse as being blown. That #13 fuse is marked as the PassKey fuse, and which I assume is part of the anti-theft system. I pulled it, and it looked OK. Then took it to the bench and used an OHM meter to bench test it -- not OK! Very strange indeed.

Finally replaced the fuse and the car started up as usual and all the settings (radio stations, seat memory, etc. were intact). A two hour ordeal because of a failed or misdiagnosed 12V test light result.

What really intrigues me is what made the PassKey fuse blow during this entire procedure. I was super careful to avoid the possibility of a short to ground situation when hooking up the auxiliary battery for the memory saver, and when removing the old battery.

Lesson learned -- even when being pro-active, "Murphy" is still out to get you; even on the most simple of tasks.
« Last Edit: May 27, 2020, 07:07:22 AM by goodfellow »

Offline fatfillup

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Re: What an ordeal -- battery change on the 2011 DTS
« Reply #1 on: May 26, 2020, 04:46:17 PM »
Glad you got it going and thank God you are smart enough to get it figured out because that could have been costly.

If I suspect a fuse, especially a low amp one, I get the continuity checker out.  Been fooled too many times

Offline Matt_T

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Re: What an ordeal -- battery change on the 2011 DTS
« Reply #2 on: May 26, 2020, 05:52:47 PM »
That fuse may be what feeds power to the DLC, aka "OBD port", and you blew it. The fact your code reader wouldn't connect suggests that you didn't have +12v at the DLC. A Passkey module being down shouldn't prevent a scan tool from communicating with the ECM. But it's a gm product so who knows. Actually IIRC there is/was a member here who was a gm diagnostics guy who might know that. CEL for an avatar.

Couple tips for hot swapping batteries. First make damn sure wherever you're introducing back-up power has power from the vehicle before you start. The fuse might already be blown. Second insulate the positive battery terminal immediately when you remove it. Personally I wrap the sucker with electrical tape. Apologies if this paragraph sounds like keyboard quarterbacking. Just trying to stop others from following the same road we've both been down.......

Offline goodfellow

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Re: What an ordeal -- battery change on the 2011 DTS
« Reply #3 on: May 26, 2020, 06:19:21 PM »
Thanks Matt -- good advice and insight on the DLC/PassKey fuse relationship. I haven't been able to find any info on it, but will dig out the PDF service manuals this evening and trace down the complete circuit just to satisfy my own curiosity. I think it was Nick (stokester) who worked at a Chevrolet dealership before he retired.

I've hot swapped more than a few batteries in this manner in the last few years, and never had an incident. I'm always super careful to prevent damage to the ECU and controls, but this time something definitely went sideways.

Offline Matt_T

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Re: What an ordeal -- battery change on the 2011 DTS
« Reply #4 on: May 26, 2020, 07:17:55 PM »
I think it was Nick (stokester) who worked at a Chevrolet dealership before he retired.

No it wasn't Stokester. He was a dealer tech and was into BMW bikes IIRC. The guy I'm thinking of worked for gm corporate on their factory service info.

And yeah definitely worth checking the wiring diagram to see if the DLC is powered by the passkey fuse.

Online J.A.F.E.

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Re: What an ordeal -- battery change on the 2011 DTS
« Reply #5 on: May 26, 2020, 07:28:00 PM »
It's torqueman22 I believe who did the GM ECM stuff.

I agree that could have been a costly trip to the mechanic if you weren't so savvy. Not that I want to generalize about mechanics but my former boss had an E150 with a no start. I know it was the relay because I swapped in a good one after checking power to the fuel pump and finding no voltage but he wanted to have it done "right" by the dealer. He did - they diagnosed it as a bad fuel pump and 700 later he had the van back.

I always check fuses with an ohm meter preferably a digital one. Been fooled a time or two with other methods.

Good advise on the swapping Matt_T especially about insulating the positive battery terminal.
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Offline torqueman2002

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Re: What an ordeal -- battery change on the 2011 DTS
« Reply #6 on: May 26, 2020, 08:54:26 PM »
<<t's torqueman22 I believe who did the GM ECM stuff.>>
Guilty!  :o

I read this with keen interest and was surprised at the root cause. While my group wrote (retired 7 years ago last Feb) the diagnostics for the ECM/ECU, I don't recall that being a failure mode we encountered.

Quite often we received 'new' vehicles with batteries that were spanked. It always seemed to be our group that wound up replacing them so we could continue developing our part of the diagnostics, we were the last in line because we required the vehicles so long.

I'm glad you tracked it down.

I know another group has responsibility for the scan tool not communicating, and that should cover this failure mode. The no start is surprising.

This is a new one on me. I use the same method for retaining codes and presets when disconnecting/replacing a battery.
« Last Edit: May 27, 2020, 10:07:17 AM by torqueman2002 »
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Offline john k

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Re: What an ordeal -- battery change on the 2011 DTS
« Reply #7 on: May 26, 2020, 10:30:21 PM »
Before I would go looking in the manual always checked all the fuses.  Amazing that a low amp fuse turned on a  circuit run by a higher amp fuse.  Been fooled by some of these plasic fuses.  Glad you got it.

Offline bonneyman

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Re: What an ordeal -- battery change on the 2011 DTS
« Reply #8 on: May 26, 2020, 11:00:23 PM »
I read somewhere about a "memory saver" idea that plugged into the cigarette lighter but my friend who is an electronics pro said don't risk it. But I know I've seen such a device for sale.

So I'm stuck in the middle. All I know is virtually every time I take the van in to get some work done I gotta reset the radio and clock.  :41:

Offline slip knot

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Re: What an ordeal -- battery change on the 2011 DTS
« Reply #9 on: May 27, 2020, 09:20:42 AM »
My 98 gm. I could hook a 9volt bat thru the cigarettes lighter and it would hold memory long enough for a battery swap. Doubt these newer rides would last long on 9 v

Offline muddy

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Re: What an ordeal -- battery change on the 2011 DTS
« Reply #10 on: May 27, 2020, 10:15:21 PM »
Ahhh I love my Plymouth the only thing it'll forget if I unhook the battery is the time and my save FM radio stations!


Kidding aside glad you were able to fix it fairly easy Ray. Like Phil said that would have been a costly fix as I assume a stealership would have quoted you a module or harness

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Offline skfarmer

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Re: What an ordeal -- battery change on the 2011 DTS
« Reply #11 on: May 28, 2020, 09:41:05 AM »
we have a fleet of gm vehicles in family. between my sons and i we have 10,12,13 and 16 silverados along with the mrs. traverse. we have never had an electronic  issue with dead batteries or swapping them out, we had an issue that ended up being the battery on  my son's 12. it would  randomly have a dead battery that we thought was a drain as there was no rhyme or reason to it. it went dead probably 20 times till it finally died completely. we would charge it up and it would load test fine until the next time. it probably had a broken connection internally. new battery, no more issues.

maybe i have just been lucky to not have any issues.
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