Complete Electrical Shutdown

[Jason55]

I've seen posts regarding symptoms such as what I have but have not seen a resolution. I have a 2009 Tahoe 2WD LT. About once a month or less the electricla system seems to go berzerk on me. The locks cycle, the gauges go nuts and the truck will shut down. If I turn the ignition off and then back on again I get nothing. The guages will not come on, the windows, power locks will not operate and the truck will not start. Its just as if I took the battery out except when it comes back to life all of the radio presets still are programmed. The Truck seems to reset itself if I turn it off, take the key out, and let it sit for a few minutes, the restart works and off I go. From schematics I have looked at it should be the Body Control Module (BCM). I cannot find any detailed info on this magical little box so I can narrow down my bad component. Has anyone else had this problem and found the fix? does anyone have any other infor on the BCM? This problem is driving my wife nutz. Thanks....

 

[85camaroman]

Its funny you mention whats happening with yours. Ive just yesterday done some recearch on this because me and my other half just picked up an 08 tahoe ltz friday night and it left her stranded at work less than 24 hours after picking it up. Exact same simptoms as you had. I came to her work and put a jumper box on it and got nothing. Checked the big battery fuse and that was good. I went home and let it sit for like 3 hours and came back, still nothing. So I pulled the battery cables off one by one and cleaned them really good and put them back on and made sure they were really tight. That fixed the problem it started right up after cleaning/tightening the cables. A fellow member on here mentioned the battery cable thing to me and it worked so give it a try.

 

[GM Customer Service]

Jason55,

I am sorry to hear that you are experiencing this issue with your vehicle. Have you consulted with your dealership to confirm if your Body Control Module is faulty?

Thank you,

Elizabeth, GM Customer Service

 

[JoeOrange]

Electrical Problesm - Will NOT Start

I joined this forum, as I have had related issues for a few years since purchasing a 2007 Yukon XL. The DAY AFTER I drove it home, it would not start; no power. I jump started it, with a battery pack, per GM instructions. This occured several times through the years. Late last year, truck had power, but would not start. Last night, same thing again. Mechanic has replaced battery, stating that it was just not recharging/ bad battery. I had read in several forums about the BCM and/ or the ignition switch being bad. My employer has quite a few Tahoe/Yukon vehicles in their fleet and the shop guys have pages of the same issues. With such a known problem, I feel like we get the run around from the GM dealers. GMC is reputed to be the best, so they should just acknowledge the problem and fix it for good.

 

[Jason55]

I read the same thing regarding battery cables but you would think the Tahoe would be a bit more robust and could handle a battery cable problem like this. From the research I've done the first thing all of my symptoms go through is the BCM. I did notice that a relay clicks when I try to use the remote to unlock doors. The doors don't unlock but I think there is a separate module that works the remote that is not part of the BCM.

So far, if I turn the ignition off and pull the key out then let it "rest" for a while it will start up again. The problem is also increasing in frequency. It was doing this about once every couple of months. Now its about once a week. Intermitent problems are the hardest to troubleshoot so I've been hesitant to bring it in. I guess its time to take the Tahoe to the doctor. Hopefully GM will remember to replace all of the parts it removes....unlike the last time my Pontiac was in .

---------- Post added at 02:34 PM ---------- Previous post was at 01:10 PM ----------

I just found out there is a couple of tech bulletins regarding this issue. The one that fits best is PIT 4846A. The bad part is there is no solution given.

Here is the description:

CADILLAC/CHEVROLET/GMC: LOCATIONS OF HIGH SPEED GMLAN WIRING CONCERNS. GAUGES INOPERATIVE, NO CRANK, HARSH TRANSMISSION SHIFTING, NO TRANSMISSION SHIFTING, DOOR LOCKS CYCLING AND INDICATORS ON. *PE UPDATED 11/17/10. *PE

 

[GM Customer Service]

JoeOrange,

I am sorry to hear you are experiencing this issue. Have you been back to the dealership to have them check your BCM or ignition switch?

Thank you,

Elizabeth, GM Customer Service

 

[Jason55]

Wow... I just got the diagnosis back from the dealership. I was told there was a voltage drop across the battery cables causing the computer to malfunction. I think this is totally rediculous that GM would design a vehicle that would be so sensitive to a battery cable issue that they would allow this not to be a recall item. My '95 4x4 gets beat to hell, still has the original battery cables and it starts just fine and always has. I sure hope GM has not designed irresponsibility into their designs. I'll see how it goes from here and I'll post any results.

 

[GM Customer Service]

Jason55,
I am glad to hear that your dealership has diagnosed the issue. I do understand your frustrations. The only way for a recall to get issued is for the incident to be documented. Your incident was documented and if a recall does happen you should receive a card in the mail letting you know.

Thank you,

Elizabeth, GM Customer Service

 

[mike1944]

Its funny you mention whats happening with yours. Ive just yesterday done some recearch on this because me and my other half just picked up an 08 tahoe ltz friday night and it left her stranded at work less than 24 hours after picking it up. Exact same simptoms as you had. I came to her work and put a jumper box on it and got nothing. Checked the big battery fuse and that was good. I went home and let it sit for like 3 hours and came back, still nothing. So I pulled the battery cables off one by one and cleaned them really good and put them back on and made sure they were really tight. That fixed the problem it started right up after cleaning/tightening the cables. A fellow member on here mentioned the battery cable thing to me and it worked so give it a try.

I agree. My Vette had the same problems. Even though the cables were tight they weren't tight enough/clean enough. Seems the computer just cannot cope with varying voltages and strange things will happen.

(Oops sorry. Didn't see that last post.)

 

[Jason55]

Seems this problem is spread across a bunch og GM products. When I hear comments like "just can't cope" it makes you wonder if problems are being addressed or is this a way for GM to get aother $1000.00 out of an already overpriced vehicle. I like my Tahoe. The way it looks and drives is what I wanted, but it is a pricey vehicle. It would be nice to know that a vehicle can withstand something like this. I know I sound like a complainer but after working 14 years in High Tech if I told a customer that the high priced system they bought couldn't handle getting power from a power supply (battery) they would pull systems off the floor or make me fix it at my companies expense.

Mike1944 - Did cleaning and re-tightening your cables fix your problem? Or did you replace the cables? This would be nice to know and I'm sure GM would like to hear the outcome so they could adjust thier repair process for this issue.

I appreciate the additional comments off of my posts. At 1st I was looking for a resolution, then it turned into a gripe. Times are tough and it would be nice to see a giant like GM help out the average Joe with a simple issue rather than tack on an additional cost at the back end just to get product to market.

Thanks again... I'll post again if my issue re-appears.. HAHA