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goodwrench9124
goodwrench9124, ASE Certified Technician
Category: Chevy
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Experience:  Ase Master Certified, GM Master Certified Tech. Awarded GM Top performer, Hybrid certified
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2005 Chevy Silverado 2500: Disable automatic door lock/unlock..key fob

Customer Question

Disable automatic door lock/unlock. 2005 Chevy Silverado 2500. Want only key fob and door-mounted-buttons to control locks. Safety issue here.
Submitted: 6 years ago.
Category: Chevy
Expert:  goodwrench9124 replied 6 years ago.

Hello, i am including a service info please read, i think this is what you are asking about.

Vehicle Personalization

Your vehicle is equipped with an automatic lock/unlock feature which enables you to program your vehicles power door locks. You can program this feature through the driver information center (DIC), or by the following method.


Programmable Locking Feature

The following is the list of available programming options:

Mode 1: All doors lock when the transmission is shifted out of Park.

Mode 2: All doors lock when the vehicle speed is greater than 8 mph (13 km/h).

The following instructions tell you how to change the automatic door lock mode. Choose one of the two programming options listed above before entering the program mode. To enter the program mode, do the following:

  1. Begin with the ignition off. Then pull the turn signal/multifunction lever toward you and hold it there while you perform the next step.
  2. Turn the key to RUN then back to LOCK twice. Then, with the key in LOCK, release the turn signal/multifunction lever. Once you do this, the doors will lock and unlock, the horn will chirp once, and a 30-second timer will begin. You are now ready to program the automatic door lock feature.
  3. Press the lock side of the power lock switch once. You will hear one or two chimes. The number of chimes tells you which lock mode is currently selected. Continue to press the door lock switch until the number of chimes that you hear matches the number of the mode that you want. If you take longer than 30 seconds, the locks will automatically lock and unlock and the horn will chirp twice to indicate that you have left the program mode. If this occurs, you can repeat the procedure beginning with Step 1 to re-enter the programming mode.

You can exit the program mode any time by turning the ignition to RUN (the doors will automatically lock and unlock and the horn will chirp twice to indicate that you are leaving the program mode). If the lock/unlock switches are not pressed while in the programming mode, the current automatic settings will not be modified.


Programmable Unlocking Feature

The following is the list of available programming options:

Mode 1: Drivers door unlocks when the transmission is shifted into PARK (P).

Mode 2: All doors unlock when the transmission is shifted into PARK (P).

Mode 3: All doors unlock when the key is removed from the ignition.

Mode 4: No automatic door unlock.

The following instructions tell you how to change the automatic door unlock mode. Choose one of the four programming options listed above before entering the program mode. To enter the program mode, do the following:

  1. Begin with the ignition off. Then pull the turn signal/multifunction lever toward you and hold it there while you perform the next step.
  2. Turn the key to RUN and LOCK twice. Then, with the key in LOCK, release the turn signal/multifunction lever. Once you do this, the doors will lock and unlock, the horn will chirp once, and a 30-second timer will begin. You are now ready to program the automatic door unlock feature.
  3. Press the unlock side of the power lock switch once. You will hear one, two, three, or four chimes. The number of chimes tells you which unlock mode is currently selected. Continue to press the door unlock switch until the number of chimes that you hear matches the number of the mode that you want. If you take longer than 30 seconds, the locks will automatically lock and unlock and the horn will chirp twice to indicate that you have left the program mode. If this occurs, you can repeat the procedure beginning with Step 1 to re-enter the programming mode.

You can exit the program mode any time by turning the ignition to RUN (the doors will automatically lock and unlock and the horn will chirp twice to indicate that you are leaving the program mode). If the lock/unlock switches are not pressed while in the programming mode, the current automatic settings will not be modified.


goodwrench9124, ASE Certified Technician
Category: Chevy
Satisfied Customers: 3420
Experience: Ase Master Certified, GM Master Certified Tech. Awarded GM Top performer, Hybrid certified
goodwrench9124 and 10 other Chevy Specialists are ready to help you
Customer: replied 6 years ago.
Okay, sort of. I see how you get into the unlocking (or locking) fature, and then select a mode. HOWEVER, I don't see how you then set your preference for a mode. Ex: Locking Feature, Mode 1. How do I disable/enable that feature?
Expert:  goodwrench9124 replied 6 years ago.
using step 3 to set the way you want, then simply turn ign key to run. let me know hows this works
Customer: replied 6 years ago.
Hello again. NOW the instructions make sense, but to no avail. It seems in the Locking feature, for example, there are only two possible states: 8 Mph OR Park. There is NO disable of locking via this method.

For the Unlock Feature, Mode 3 or 4 might be acceptable. HOWEVER, never got Step 2 to work: no lock-unlock-beep result? But that's moot.

Okay, we try a different path. Can you recommend a really good book (CD) that has a detailed wiring diagram for my 2005 Silverado 2500 and body how-to (e.g. remove door panels)?

I'm a bored retired Rocket Scientist (no kidding) and the challenge of hacking the "smart" door locks is exciting!

Thanks for your support! Keith
Expert:  goodwrench9124 replied 6 years ago.

Very good, our vehicles of today are not far off from being rocket science!!!! after doing some more research, i have come up with a service documents for your concern. the door locks operation is programmed into the body control module. body control module is a simple computer that works off a serial data line that communicates with the door modules. oh yes the door switches that are mounted in the door are actually working computers. the switches work like a key board for a pc. they are simple data imputs to the bcm and door modules.

Models:2005-2008 Cadillac Escalade, Escalade ESV, Escalade EXT
2005-2008 Chevrolet Avalanche, Silverado, Silverado Classic, Suburban, Tahoe
2005-2008 GMC Sierra, Sierra Classic, Yukon, Yukon Denali, Yukon XL, Yukon Denali XL



 

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:

Some customers may comment that they are unable to override the automatic door locking feature. In prior model years, customers were able to select "Doors Lock Manually" from the DIC. However, starting in the 2005 model year, this selection was removed.

Recommendation/Instructions:

Since the 2005 model year, all BCM's (Body Control Modules) are programmed from the factory to allow two personalized door lock settings:

Setting 1: All doors lock when the transmission is shifted into gear.

Setting 2: All doors lock when the vehicle speed is greater than 8 mph (13 km/h).

 

FIGURE Driver Door Module (DDM) References - 2 of 2(c)


Object Number:(NNN) NNN-NNNN Size: FS

FIGURE Driver Door Module (DDM) Power, Ground, Serial Data and References - 1 of 2(c)


Object Number:(NNN) NNN-NNNN Size: FS

Customer: replied 6 years ago.
Reply to goodwrench9124's Post: Ah the good old days of a two-barrel, points and condenser. I agree, and even rocket science isn't of great use! The days of the Saturday Mechanic are long gone.

Okay. In looking at Schematic DDM #1 it looks like the internals of the DDM/door switches are fine. The "Door Lock Schematics" connected via serial bus to the DDM may hold some promise. Do you have a link to those schematics?

Initial thoughts are:

1. R&R. Remove the 2005 BCM and Replace with a 2004 DCM. But that's brute force and probably very pricey, and may have compatibility issues.

2. Spoof the smarts.

Lock Mode 2 needs a thresholded vehicle speed sensor. Somewhere a device determines vehicle speed and when the 8 Mph limit is crossed, it notifies the lock smarts. So if that sensor link (wire?) can be severed, the smarts never think they need to lock the doors. Q: Is vehicle speed for locking determined by tranny electronics or speedo electrics, or is there a driveshaft pickoff? Maybe this is the more difficult way.

Lock Mode 1 needs a not-in-park signal. (The description says "shifted into gear" but a guess is that it's really a not-in-park function.) Is that done with a shift position mechanical limit switch (easy to spoof) or is it something in the tranny electronics that provides the not-in-park signal?

---
A complete set of detailed schematics plus your savvy/expertise/experience can be of great help in reducing these guesses to reality! Where can I get the best detailed schematics? Chevy dealer OEM manual? A book store or online source? (There are several advertised independent schematic providers.)

---
By the way, the comment about safety is a real concern (at least for me). There are several scenarios where a door needs to be opened quickly from the outside. Examples: Heart attacks, kids fooling around in the driver's seat, etc. And the unlock when put in park is a perfect way for a carjacker to gain access: hide in a lot until a victim pulls into a slot, then spring up and rip open the door before the driver has had a chance to check for such risks and unlock him (her) self.

Enough babeling. Thanks again for your interest. Keith
Expert:  goodwrench9124 replied 6 years ago.

Hello, lets start with the safety concern. I can see your side of the concern. but here are the facts as i know them. when we build a vehicle, there is allot of thought and testing that go into safety.but here is the kicker we still have our legal system to deal with. why some changes of operation take place. originally gm built the vehicle with many programable features. thought being let the customer choose the way they want there vehicle to operate. that is all fine and dandy, until something happens and there is a big lawsuit!!! and then it is back to the drawing board. lets make the functions less changeable. taking the risk factor out of the picture. What most people dont stop and think about. we as car builders, have to think about the legal end.

back to the task at hand. as far as using a 04 bcm, possible but creates a whole new set of problems. bcm are originally set up with some basic information and then is finished programed at the dealer for each vehicle. Oh and the bcm are VIN stamped. as a dealer, we have only limited ways we can program,. when we set up a bcm for a vehicle we use a scan tool and a pc link to gm. and we simply program by answering software questions by a yes or a no.

The comment about trying to fool system with the mph. there is where things get real tough. The data line that connects every module on your vehicle caries information back and forth between modules. kinda like the internet. The power control module is in charge of the mph function. so the pcm just simply talks to the bcm and says hey i am 8 mph lock the doors. the same hold true for the park and neutral. the information is sent via of data line to the bcm, hey bcm i am in gear lock the doors.

Our vehicles of today have become a rolling internet. some vehicles have a small number of modules say about 5 to all the way up to 28 modules. the point being all the modules have a specific job to do, but share all their information with other modules to perform other tasks. even the radio in your vehicle is on the data line it has other roles in the system other than playing tunes.

 

as far as diagram's and repair information, the last i heard there approx. 15,000 pages of documents per vehicle. if there is something specific you need i can help. but if you really want to have access to all the information. you can still buy repair manuals thru your dealership.

Customer: replied 6 years ago.
Right. Lawyers and Big Brother. What a combination auto makers have to deal with!

I'm thinking again about the Park switch. Is there something like a column switch? Or does the signal (on the serial bus) come from a tranny module (assuming there is one.

What the bus is doing is, in the big picture, transmitting what the driver has done with mechanical motion: physically moving the shift selector. And somewhere (column/tranny innards) that mechanical motion has to be sensed and transformed into code on the serial bus. So, it's that actual mechanical motion at the root of Locking Mode 1. There has to be a transducer somewhere in the chain: so where is it?

15,000 pages sounds like aerospace documentation! Actual paper manuals are pretrty much useless if one doesn't know quite what to look for. Is there an electronic version (e.g. CD-ROMs or online) where one can rapidly search?

Do you know what/where that mechanical motion (shift lever physical position) is translated to electronic data? Again, thanks for the interesting chat. Keith
Expert:  goodwrench9124 replied 6 years ago.

Hello again. let me first say it has been a real pleasure chatting with somebody like yourself. you seem to have a understanding on what actually happens with our vehicles of today. to answer your question about the park switch. there is mechanically operated switch mounted on the side of transmission, which is operated by the shift linkage. here again same principle, the switch is merely a input to the the power control module. once a action has taken place by the shifter the prndl switch say to the power control module i am now in gear, the pcm in turns tell the bcm, hey we are now in gear, the bcm now says to the door module hey we are in gear do something with the door locks.

There are some after market company that you can purchase service information on any vehicles. such as alldata, and there are some others. you can purchase several different ways. you can buy a one time c/d pretty pricey, some where in the 1000.00 range. or you can purchase by paying a monthly service fee. pretty pricey too.

your vehicle works off what they call a uart bus line. now this system is really getting out dated. now we are using gm lan high speed data bus lines which uses two serial data lines. we have to use a special adapter for our scan tools to slow the information down, so we can read what are the systems are doing. who knows what will happen in the next 10 years. look out George jettson!!!

here is a wiring diagram on how some of the bus line works.

FIGURE Power, Ground, DLC and Splice Pack SP205(c)


Object Number:(NNN) NNN-NNNN Size: FS

Customer: replied 6 years ago.
Hi again,

I'm still cogitating! More later when (if!) I get anywhere with the puzzle. I'll be back. Keith
Expert:  goodwrench9124 replied 6 years ago.

Ok, looking forward to hear from you!!!

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