Blowndenalixl

So I think the old Denali is just plain pissed that it is being replaced by the new one, but SUVs don't have feelings, do they?

At any rate, since we have stopped driving the 03 denali xl on a daily basis, it can't last more than 3 or 4 days without the battery going dead. I just put in a new interstate battery in July, and had it replaced last week in an effort to combat this problem. My wife drove it home from the shop on Monday afternoon, and I checked today and the brand new battery is dead again.

This is the same vehicle that has been left in -20c weather for 2 weeks straight in the middle of winter while we were away in Arizona, and started up no problem when we returned.

So I am at a loss as to what is causing the battery drain. The shop measured the discharge rate last week and deemed it acceptable. The only change to the vehicle in the last year was the installation of a new car starter system, and a cord such that my wife could run her IPhone off of the car stereo.

Might either of those two items be causing this? Short of that, the only other thing I can think of is the alternator. But I (supposedly) started with a new interstate battery on Monday, and it is dead again by Thursday, failing after 3 days just like the old "new" interstate battery.

Any thoughts on how I might diagnose the culprit are appreciated.

AKlowriderZ71

iTrader: (22)

Is your new auto-start a 2-way system?

Blowndenalixl

Yes it is a Compustar command start.

Edit - did a google on "Compustar kills battery" and got some hits. Going to have it checked out by the Audio shop that installed it last year. Fingers crossed. Thanks for the suggestion AK.

DrX

iTrader: (7)

I have had remote start units go bad on my vehicles and cause excessive parasitic drain. Also, once I traced it to a bad HVAC module and another time it was a factory remote doorlock module. Have to measure the drain and start pulling fuses until you isolate the circuit responsible and then work down from there.

If the measured drain is within spec, then check the charging system. Is the battery seeing at least 14V with the engine running? I'm sure the shop must have checked this also. One of my kids cars was eating batteries and everything checked out OK. I just happened to catch it one time when the battery was not charging - turns out the alternator had an intermittent issue.

AKlowriderZ71

iTrader: (22)

I think you're on the right track now.

Blowndenalixl

Thanks Dr X. Will definitely check that out if the stereo shop investigation of the car starter does not turn up anything. The AMA battery technician told me that some starters have up to 6 relays, and if one goes bad, it can stay hot and drain the battery quickly. This is apparently a very common problem, but not one I have ever had before with car starters.

The battery is good and drained down to 2 kV each time. But when charged, it does run at 14 kV when running.

Very neat setup you have there by the way. Thanks for weighing in.

ChevyTruck

iTrader: (39)

You may want to check your starter also, I had 3 battery's die in 1 month and I replaced my alternator and then talking to a local parts store owner he advised me to bring my starter in and have it tested. Come to find out it was draining my battery every time I started it. It's worth a try to have it tested first. Also I have a remote starter on my truck.

Blowndenalixl

Will keep that in mind as well. This thing is for sale, and I don't want this problem to go along with the vehicle to whoever purchases it so I am going to do whatever it takes to fix it.

Blowndenalixl

So my stereo shop tested and, because they could not find anything amiss, disconnected the car starter and ipod connection today, and also did some battery draw testing for me. Oddly enough, the draw went up from 65 mA to 85 mA after the starter was removed.

Some other strange things that have been happening over the last year or so is that sometimes I will get an error when I try to turn on the car saying "Driver unknown" instead of "Driver 1" or "Driver 2", and then the car will start and shut down. Also, other errors appear such as "stability system disabled". Anyways, after awhile, the system will reset itself, and all will work fine again.

Was talking with my tuner and he recalled that certain ipod connection devices connected to the body control module had impacted the body control module. So did some more research on ipod impact on body control module and by luck found out that apparently there was a GM flash upgrade for 02's and 03's which was related to correcting a battery drain problem.

So that is next on my checklist of "things to try". Will share the results if I ever get to the bottom of this. I feel so scattered but of course now that this is acting up, lots of folks are lining up to come see the vehicle with (hopefully) an eye to buy.

Blowndenalixl

Further update - had my mechanic do a reflash of the body control module today, and the results are positive. They did a draw reading after the flash, and the reading was either 7 mA or 0.7 mA (he gave me the number in amps and I can't recall how many 0's there were).

At any rate, I am going to see if this solves the problem after leaving the vehicle parked for the next 4 days. I will then reintroduce the car starter, and check the draw. I think the ipod connection is on the fence as to whether or not I will reintroduce it - may just leave it be.

Fingers crossed the old girl starts up in 4 days!