automatic door locks

industrial · March 30, 2005

I have a 2005 GMC 2500 HD & I just have to find a way to disconnect them. I understand it was a law that was implemented at the end of 2004. There has to be a real smart guy out there that can help all of us out that can`t deal with the powers that be that tell us our doors have to automatically lock. This is just crazy!

Thank you in advance.

Wingnut · March 30, 2005

Don't take this the wrong way...But I just don't see why some people get so "unlocked" about this feature.

I can think of very few situations where you would need to be driving with a door open. And that button isn't hard to press at all, when it comes time to do it.

I actually kind of like the auto-lock feature.

But to each his own.

Do a search on the board here, it's been discussed.

industrial · March 31, 2005

Don't take this the wrong way...But I just don't see why some people get so "unlocked" about this feature.

I can think of very few situations where you would need to be driving with a door open. And that button isn't hard to press at all, when it comes time to do it.

I actually kind of like the auto-lock feature.

But to each his own.

Do a search on the board here, it's been discussed.

<{POST_SNAPBACK}>

Why would I want my doors to lock automatically. I hope there is not a time when you get in a accident & your doors are locked & your stuck or god forbid knocked out but i guess they could break the window. In this controlling world we live in we should have the option of locking them ourselves or for people like you that like to push buttons just so you can get out of your car you can have that option. What ever turns your skirt i just think it's ridiculus. I suppose your one of those people that need to have one of those annoying door chimes to let you know that you left your keys in the ignition or my golly i didn`t close my door all the way. So for all of us that can think for ourselves i hope someone out there can help me out.

lrymal · March 31, 2005

I raise this each time the auto-lock discussion comes up... Has anyone investigated going to an aftermarket alarm / keyless entry system? Would installing this, bypassing the factory locking system, solve the problem?

If the auto-lock issue is a paramount issue, I would certainly invest a bit and do this, if it would work. I know it would be under $200.

GM-Tech · March 31, 2005

The locking and unlocking of the doors is not a simple process that can be thwarted by simply removing a wire. Adding an aftermarket system would probably not help because they typically are set up to use existing systems in the vehicle to activate the actuators.

There are so many modules involved and so many signals, it's not something I would want to attempt to override. Here's the "Description and Operation" of the power locks. This covers utilities too, so just ignore the part about cargo doors and hatches if it doesn't apply. The rest is basically the same...

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Power Door Locks Description and Operation

Door Lock System Components

The power door lock system consists of the following components:

The driver door module (DDM)

The passenger door module (PDM)

The body control module (BCM)

The driver information center (DIC)

The rear door lock switch

The door lock relay

The door unlock relay

The liftgate lock relay--utility vehicles with liftgate only

The reversible door lock actuators in each of the doors and liftgate

LOCKS 20A fuse (rear lock/unlock relay supply voltage)

ECC 10A fuse (liftgate lock relay supply voltage)

Door Lock System Controls

The power door lock system can be controlled by any of the following:

A power door lock or unlock switch activation

A keyless entry transmission

An automatic door lock function

A delay lock function

Door lock cylinder switch activation

Lockout Prevention

An airbag deployment

Driver, Passenger and Cargo Door Lock System Operation

The front power door lock switches are integral components of the driver door module (DDM) and passenger door module (PDM). The switches are two position normally open rocker switches. When placed in either the lock or unlock positions, the switches provide a direct input to the DDM or PDM. The DDM or PDM monitors these inputs and sends a Class 2 message indicating a change in the switch's respective position. Modules which activate the power door lock motors receive the Class 2 message and activate the motor in the appropriate direction to lock or unlock the vehicle's doors and liftgate. The rear door lock switch provides a lock and unlock signal to the body control module (BCM). The BCM upon receipt of a lock or unlock signal will control the rear door lock relays and also send a Class 2 message to the DDM and PDM to perform the appropriate function.

The modules which activate the power lock motors are:

The DDM (driver door lock actuator).

The PDM (passenger front door lock actuator).

The BCM (both rear door lock actuators and cargo door/liftgate).

The DDM and PDM are directly connected to the respective door lock actuator through the door lock motor lock and unlock circuits. Once a door lock or unlock request has been received, the module will supply battery voltage to one side of the actuator and ground the other causing the doors to lock or unlock.

The rear passenger and cargo doors differ slightly in that they use lock and unlock relays. The relays supply and coil sides receive a constant voltage through the battery voltage supply circuit. The normally closed contacts are connected to ground and the control side is connected to the BCM. Once a door lock or unlock request has been received by the BCM, the BCM will ground the control side of the appropriate relay. This energizes the relay and allows voltage to be applied to either the door lock motor lock or unlock circuits. since the other side of the door lock actuator is connected to the normally closed contacts of the opposing relay to ground, the doors lock or unlock.

Liftgate Locking Operation

The liftgate will lock any time the vehicle is shifted out of park on vehicles equipped with an automatic transmission and at vehicle speeds exceeding 5 kph with manual transmission. This happens in conjunction with auto door locks if enabled or independently of auto door locks if the feature is disabled. This ensures that the liftgate is locked anytime the vehicle is shifted out of park or when the vehicle is in motion.

The liftgate lock relay supply and coil sides receive a constant voltage through the battery voltage supply circuit and the ECC fuse. The normally closed contact is connected to ground and the control side is connected to the body control module (BCM). A lock function will occur when a door lock switch activation, keyless entry lock transmission, auto door lock function or a liftgate lock function has been received by the BCM. The BCM will then ground the control side of the liftgate lock relay. This energizes the relay and allows voltage to be applied to the liftgate lock actuator lock control circuit. Since the other side of the liftgate lock actuator is connected to the normally closed contacts of the door unlock relay to ground, the liftgate will lock. When an unlock function occurs the BCM will ground the control side of the unlock relay and the rear doors and liftgate will unlock.

The BCM also runs diagnostics on the liftgate lock relay control circuit and will set DTC B3825 as current and also send a Class 2 message to the DIC. The DIC will display REPLACE LIFTGATE FUSE to inform the driver that a fault has been detected in the liftgate lock circuit and that the liftgate is not locked. Faults that will set the DTC and cause the DIC to display the message could be any of the following:

An open ECC fuse

An open or short to ground in the liftgate lock relay battery positive voltage circuit

A faulty liftgate lock relay

An open or short to ground in the liftgate lock relay control circuit

A short to ground in the liftgate lock actuator lock control circuit

A faulty BCM

Programmable Automatic Door Locks

The automatic door lock feature can be programmed to control the door lock system. The automatic door lock feature is factory programmed to have all doors lock and unlock. For detailed instructions on programming the automatic door locks, refer to Vehicle Personalization in Personalization.

When the automatic door lock feature is programmed to control the door lock system, the driver door module (DDM), passenger door module (PDM) and body control module (BCM) will lock the vehicle doors if the following inputs are true:

Ignition 1 input is active.

All door jamb switch inputs are inactive.

Cargo door or liftgate/liftglass ajar inputs are inactive.

Transmission is shifted out of park.

This automatic door lock function will only occur once per ignition cycle unless, a door jamb switch input changes state to active and back to inactive. Then the DDM, PDM and BCM will lock all doors again.

Once the automatic door lock feature has locked the doors, the BCM will then unlock all the doors when the transmission is shifted into park.

Lockout Prevention

This feature prevents the locking of the driver door if the ignition key is left in the ignition lock cylinder. If a lock function occurs from any door lock switch and the body control module (BCM) senses an active state on either the left front door latch signal, secondary door latch switch signal and/or the liftgate ajar switch signal circuits and the key in ignition switch signal circuit is in the YES state, the BCM, driver door module (DDM) and passenger door module (PDM) will lock the doors and then the DDM will unlock the driver door.

Delayed Locking Operation

With any door open and a door lock switch is activated in the lock position, the driver door module (DDM), passenger door module (PDM) and the body control module (BCM) will go into a lock pending state. The BCM will also give three audible chimes. When the door is closed, the DDM, PDM and the BCM will lock the doors after approximately five seconds. This feature can be overridden by activating the door lock switch a second time and the doors will lock even with a door open.

Unlock After Air Bag Deployment

This feature will unlock all of the vehicle doors 15 seconds after an air bag deployment.

jhm · March 31, 2005

Are you saying the '05's cannot have the door locks programmed like earlier models? That would really suck. Is it on all makes/models or just trucks?

silvius · March 31, 2005

Don't take this the wrong way...But I just don't see why some people get so "unlocked" about this feature.

I can think of very few situations where you would need to be driving with a door open. And that button isn't hard to press at all, when it comes time to do it.

I actually kind of like the auto-lock feature.

But to each his own.

Do a search on the board here, it's been discussed.

<{POST_SNAPBACK}>

Why would I want my doors to lock automatically. I hope there is not a time when you get in a accident & your doors are locked & your stuck or god forbid knocked out but i guess they could break the window. In this controlling world we live in we should have the option of locking them ourselves or for people like you that like to push buttons just so you can get out of your car you can have that option. What ever turns your skirt i just think it's ridiculus. I suppose your one of those people that need to have one of those annoying door chimes to let you know that you left your keys in the ignition or my golly i didn`t close my door all the way. So for all of us that can think for ourselves i hope someone out there can help me out.

<{POST_SNAPBACK}>

Industrial, take it easy. If you don't agree with a response to a post, (especially one from a moderator) there are better ways to respond. Disagreeing is ok, but do it with respect.

Colorado Kid · April 6, 2005

Besides, as I read it, 5 seconds after my air bag blows the doors will unlock. We've got pretty speedy EMS response, but they don't generally get there quicker than 5 seconds!

I know that there are circumstances that the engineers in Michigan and Politicians in Washington apparently can't forsee where it would be nice to be able to open the doors while the vehicle is moving.

By the way, if this is some new law then why doesn't my friend's 2005 Honda Accord (with power door locks) have auto locking?

I think "It's the law" is but that doesn't help unlock the doors.

Wingnut · April 7, 2005

Don't take this the wrong way...But I just don't see why some people get so "unlocked" about this feature.

I can think of very few situations where you would need to be driving with a door open. And that button isn't hard to press at all, when it comes time to do it.

I actually kind of like the auto-lock feature.

But to each his own.

Do a search on the board here, it's been discussed.

<{POST_SNAPBACK}>

Why would I want my doors to lock automatically. I hope there is not a time when you get in a accident & your doors are locked & your stuck or god forbid knocked out but i guess they could break the window. In this controlling world we live in we should have the option of locking them ourselves or for people like you that like to push buttons just so you can get out of your car you can have that option. What ever turns your skirt i just think it's ridiculus. I suppose your one of those people that need to have one of those annoying door chimes to let you know that you left your keys in the ignition or my golly i didn`t close my door all the way. So for all of us that can think for ourselves i hope someone out there can help me out.

<{POST_SNAPBACK}>

OK, you took it the wrong way.

Sorry.

redvett · April 7, 2005

In the early 90's i was driving my 70 Chevelle SS454 and stopped at a traffic light in the early morning with the windows rolled down. I guy ran up to the car and tried to open the door, realizing that he was trying to get in i dropped the clutch and floored it. I had him running along for a bit until he let go of the door handle. Bet his hand stung for a while.

I am now glad that the doors lock each and every time. I can always unlock them to let someone in.

Trouttrooper · April 9, 2005

One thing I have noticed that REALLY bugs me is the following scenerio, which is going to get old real quick when it comes to picking up hay this summer with people getting in and out of the truck constantly.

1. doors lock when taken out of park (auto tranny)

2. drop off wife which means I press the unlock button

3. Wife gets out, closes door, and I drive off.

4. !#$% doors lock themselves AGAIN! when I start moving (I never take it out of "D")

I thought once you unlocked the doors they stayed unlocked until the engine is turned off or you cycle it through park?

I still think the way to do it is to interrupt the signal the BCM gets when you take the tranny out of park. Everything else would still work, the truck would just think it never goes out of park. I guess I could always pull fuses when I get hay so the doors won't be constantly locking.

Another thought with the other "programmable function option", could you change the speed when it locks the doors to say 100mph?

GM-Tech · April 9, 2005

I still think the way to do it is to interrupt the signal the BCM gets when you take the tranny out of park.

That might not be so easy. I haven't looked at the schematics, but I strongly suspect the BCM gets that information over the class 2 data line. In other words, the trans shift position is an input to the PCM, not the BCM, and the PCM sends that information to the BCM over the data line.

The PCM obviously needs to know what gear you've selected, so you can't disable that input. And you can't just stop all data going from the PCM to the BCM and vice versa. For one thing, the passlock password is sent via class 2 and the truck wouldn't start without it. Nope, it ain't so easy.

So which is worse. Having them lock automatically or not work at all? If the former, then just disable the darn things completely so you no longer have power locks.

Trouttrooper · April 9, 2005

That might not be so easy. I haven't looked at the schematics, but I strongly suspect the BCM gets that information over the class 2 data line. In other words, the trans shift position is an input to the PCM, not the BCM, and the PCM sends that information to the BCM over the data line.

The PCM obviously needs to know what gear you've selected, so you can't disable that input. And you can't just stop all data going from the PCM to the BCM and vice versa. For one thing, the passlock password is sent via class 2 and the truck wouldn't start without it. Nope, it ain't so easy.

So which is worse. Having them lock automatically or not work at all? If the former, then just disable the darn things completely so you no longer have power locks.

<{POST_SNAPBACK}>

Oh well

I'll probably just pull fuses when I'm in the hay fields but power locks are sure beneficial with 4 doors for everyday use, especially since there's no darn keyhole on the passenger side.

Maybe if GM gets enough complaints they'll change things back. I'm obviously not the only one complaining because when I first went to the dealership to have them disabled they had a stack of the notices from GM describing the inability to disable auto locks on 2005 models that they were handing out to the public.

still better than a F*** or D****

GM-Tech · April 9, 2005

I work in a dealership and no one has complained to us. I'd also like to know where these "stack of notices" from GM came from. I have seen no such notices.

mmmikkke · April 10, 2005

There's a vehicle speed sensor wire somewhere on the vehicle--maybe even in the radio harness--and it's pretty simple to intrepret the vehicle speed sensor signal with one or two simple IC's, so all somebody needs to do is design a circuit that senses the lock status at say 7 mph, and then if they were not locked, waits for 8.001 mph and unlocks the doors that were just locked by the evil computer when the vehicle speed reached 8 mph.

I could probably even make one myself. I just might do that.

Every time the computer locks the doors against the driver's wishes, the added circuit unlocks them a second later. Ha-ha, problem solved.

The epic struggle between good and evil will play out over and over, throughout your trip. Good triumphs over evil. Over and over. It'd be great entertainment!