New guy that has a couple of questions.

[Unclemuir]

I have a 2011 Tahoe LT Flex Fuel with 51k miles. I have owned it since new. In the first 5 years the dealer replaced (or said they did) the AGM battery 9 times. A month or 2 would go by before the battery would be dead after some use. The dealer kept telling me it has a draw that is why it would go dead. I got tired of the excuses they had and went out and bought a flooded battery that lasted almost 10 years without a single problem until it was dead one day last week. I put another new flooded battery in and it starts up and shows it is charging but the radio won't turn on and the rear parking sensors will not go on. This is the same problem I had the last time I changed the battery. They both started working again after a couple of days the last time. They show no change this time.. I have ordered a new negative wiring cable set it will be here today. I see that many do not like the cylinder shut off as some have had a problem with them. On E bay I saw a positive battery cable that deactivates the cylinders. Has anyone had any experience with these?

Any input would help. I was a sports car mechanic for many years and then restored Old Mercedes for museums and private collectors for 20 years. Other than having battery problems this has been a great truck.I replaced the tires and wiper blades and change the synthetic Mobil 1 @7500 miles. That is all I have done in 51k miles. Am i headed in the right direction in changing the negative cables for my problem. I am in Los Angeles.

 

[Doubeleive]

have you tried just disconnecting the battery again? while it is disconnected you can take both the positive and negative cables off and touch them together for a few seconds. doing that dissipates any stored electricity and clears it all out. Then reconnect and see if that works.

 

[mikez71]

That is a stock battery cable for trucks with AFM, you need to get a device or have AFM tuned out.
Getting it tuned out is best, cheap at lt1swap.com.

 

[Charlie207]

Shifting into Manual Mode - Gear 5 will disable the AFM for diagnostic purposes, which is fine unless you are on the interstate or don't care about cruising at higher RPMs. When you cycle your dashboard info-display you should see a readout that displays something like "Instant MPG - V4 or V8 mode". You'll be able to see that in Gear 5 your engine stays in V8 mode.

It'll drive normally, and upshift/downshift fine, but just with 5 gear ratios instead of 6.

 

[Doubeleive]

On E bay I saw a positive battery cable that deactivates the cylinders. Has anyone had any experience with these?
must be a typo

 

[Unclemuir]

have you tried just disconnecting the battery again? while it is disconnected you can take both the positive and negative cables off and touch them together for a few seconds. doing that dissipates any stored electricity and clears it all out. Then reconnect and see if that works.

I tried that yesterday and it still didn't work. I almost have the new negative Battery cable installed and will try it again. The negative cable I am changing gave me problems when I first bought this truck. The door locks would lock and unlock and the power would surge. I took the cable off the battery and gave it another twist to tighten up the wires and it worked great until now. I will let you know if it works tomorrow. Thanks

 

[Unclemuir]

I tried that yesterday and it still didn't work. I almost have the new negative Battery cable installed and will try it again. The negative cable I am changing gave me problems when I first bought this truck. The door locks would lock and unlock and the power would surge. I took the cable off the battery and gave it another twist to tighten up the wires and it worked great until now. I will let you know if it works tomorrow. Thanks

I have now tried disconnecting the cables and holding the cables against each other a few times and still no change. I will try looking at some other things tomorrow. Just no radio
bluetooth or parking assist.

 

[kbuskill]

I have now tried disconnecting the cables and holding the cables against each other a few times and still no change. I will try looking at some other things tomorrow. Just no radio
bluetooth or parking assist.

The battery cables are a known problem area on these trucks as they like to corrode internally which wreaks havoc on the electrical systems since there are so many modules that are very sensitive to voltage fluctuations.

I see you already purchased, and presumably installed, a negative battery cable. I would suggest replacing the positive cable as well.

Beyond that, have you checked for any blown fuses for the devices you are having issues with?

Also, the fuse box under the hood is another area which can get dirty/corroded connections. Sometimes just unlatching the camlocks (gray handles on either side) on the fuse box and lifting/jostling it around and re-seating it and locking it back down is enough to "clean" the connections underneath and fix the issue.