How JustAnswer Works:

  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.

Ask John Your Own Question

John
John, Master A.S.E Automotive technician
Category: Chevy
Satisfied Customers: 9176
Experience:  A.S.E MasterTechnician A1-A8 w/L1,38 years experience General Motors Master Technician
6408229
Type Your Chevy Question Here...
John is online now
A new question is answered every 9 seconds

My door locks and power windows will not work

Resolved Question:

my door locks and power windows will not work
Submitted: 5 years ago.
Category: Chevy
Expert:  John replied 5 years ago.

HelloCustomer

The power windos & door locks for your vehicle is operated by by the BCM(body control module) which uses several other parts for input & output.The thing I have seen the most of is the drivers door module failing.A scan of the BCM with a class 2 scan tool is the way to start.All functions are monitored & usually will set a trouble code when they fail.I am sendind a description of operation to help.

The power door lock system consists of the following components:

Driver Door Module (DDM)
Passenger Door Module (PDM)
Liftgate Module (LGM)
Door lock relay
Door unlock relay
Body Control Module (BCM)
Reversible door lock actuators in each of the doors
LR/RR LOCKS 10A fuse (relay supply voltage)
Door lock switches in driver and passenger doors (switches are integral components to the DDM and PDM)

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
Door lock cylinder switch activation
Lockout Prevention
An airbag deployment

The power door lock switches are integral components of the DDM and 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 modules which activate the power lock motors are:

DDM (driver door lock actuator).
PDM (passenger front door lock actuator).
BCM (both rear door lock actuators).
LGM (liftgate door lock actuator).

The DDM, PDM and LGM 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 passengers 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.

 

The power window system consists of the following components:

Driver door module (DDM)
Passenger door module (PDM)
Body control module (BCM)
LR power window switch
RR power window switch
Window up and window down relays in each of the rear passenger window switches
Window lockout switch
Reversible power window motors in each of the doors (circuit breaker protected)
LT DOOR CB 25A (System power for left rear window)
RT DOOR CB 25A (System power for right rear window)

The power window system will operate anytime the retained accessory power (RAP) system is active or when the ignition switch is in the ACCY or ON position.

The DDM contains 4 power window switches which are integral components. Closing any of the normally open, rocker type switches provides the DDM with a request for power window operation. The switches for the 2 front windows have 3 positions Up, Down and Express Down, while the switches for the rear windows have only 2 positions, Up and Down. Each of these switches and their positions is a direct input into the DDM. Upon receiving a request for power window operation, the DDM, transmits a class 2 message indicating the switch and it's changed position.

The PDM contains a single power window switch that is an integral component. Closing of this normally open, rocker switch provides the PDM with a request for the front passenger power window operation. The switch for the front passenger window has 2 positions Up and Down. Each of these switch positions is a direct input to the PDM.

The 2 rear passenger doors have there own switches. Each of the switches contain a power window up and down relay. A switch activation alone can control the up and down functions of the rear windows. However the BCM, upon receiving a class 2 message from the DDM, can control the set of relays which will activate the rear window motors.

A permanent magnet motor operates each of the power side windows. Each motor raises or lowers the glass when the motor receives voltage. The direction the motor turns depends on the polarity of the supply voltage. The power window switches control the polarity of the supply voltage. A built-in circuit breaker protects each motor. The circuit breaker opens when the switch is depressed for a extended period of time under the following conditions:

The window has an obstruction.
The window is fully open or fully closed.

The circuit breaker will reset automatically as the circuit breaker cools, however 5-15 seconds may elapse before the circuit breaker resets.

The switch for the driver power window has 3 positions Up, Down and Express Down and its position is a direct input into the DDM. Upon receiving a request for power window operation (switch activation), the DDM supplies voltage to the power window motor left front up or down circuit and grounds the opposite and the power window motor runs to move the window up or down.

The switch for the front passenger power window has 2 positions Up and Down, and its position is a direct input into the PDM. Upon receiving a request for power window operation (switch activation), the PDM supplies voltage to the power window motor right front up or down circuit and grounds the opposite and the power window motor runs to drive the window up or down.

The front passenger power window can also be controlled from the power window master switch. The power window master switch for the front passenger power window has 3 positions Up, Down and Express Down and its position is a direct input into the DDM. Upon receiving a request for front passenger power window operation (switch activation), the DDM transmits a class 2 message indicating the changed switch position. When the PDM receives this message, the PDM supplies voltage to the power window motor right front up or down circuit and grounds the opposite and the power window motor runs to move the window up or down.

The passenger power window switches incorporate window up and down relays. The supply side of all the window up and down relays receive voltage through the battery voltage supply circuit and the LT DOOR or RT DOOR circuit breakers respectively. The normally closed contacts of each relay is connected to ground. The load side of each of the relays are connected to either side of the power window motor through the power window up and down circuits. The relay coil feed circuits are connected to the BCM through the power window lockout control circuit and the relay control circuits are connected to the power window switches and to the BCM.

If a rear power window switch is placed in the down position, the down relay would energize and allow battery voltage to the power window motor through the power window motor down circuit. Since the opposite side of the motor is connected to the normally closed contacts of the up relay to ground through the power window motor up circuit, the window moves down. If a rear power window switch is placed in the up position, the up relay would energize and allow battery voltage to the power window motor through the power window motor up circuit. Since the opposite side of the motor is connected to the normally closed contacts of the down relay to ground through the power window motor down circuit, the window moves up.

The rear passenger power windows can also be controlled from the power window master switch. The power window master switches for the rear passenger power windows have 2 positions Up and Down and its position is a direct input into the DDM. Upon receiving a request for rear passenger power window operation (switch activation), the DDM transmits a class 2 message indicating the changed switch position. When the BCM receives this message, the BCM can control the rear window up and down relays.

The express down function controls both the driver and front passenger power windows but only from the driver door power window master switch. When either the driver or front passenger window switch is momentarily depressed to the express down position, it is a direct input into the DDM. If the request was for the driver power window, the DDM supplies voltage to the power window down circuit continuously until the power window reaches the bottom of its travel. At this point, the DDM senses an over current situation on the power window down circuit and interrupts the voltage supply. If the request was for the front passenger power window, the DDM transmits a class 2 message indicating an express down function was requested. When the PDM receives this message, the PDM supplies voltage to the power window down circuit continuously until the power window reaches the bottom of its travel. At this point, the PDM senses an over current situation on the power window down circuit and interrupts the voltage supply.

The DDM contains a window lockout switch that is responsible for the disabling of all the passenger windows from the individual passenger window switches. When the window lockout switch is activated, the DDM transmits a class 2 message indicating that a window lockout request has been received. When the PDM receives this message, it will disable the power window motor up and down circuits. When the BCM receives this message, it will interrupt the up and down relay coil feed voltage for both rear doors. Once activated, the lockout feature will remain in effect until the ignition switch is cycled or the DDM receives another power window lockout switch activation.

John, Master A.S.E Automotive technician
Category: Chevy
Satisfied Customers: 9176
Experience: A.S.E MasterTechnician A1-A8 w/L1,38 years experience General Motors Master Technician
John and 10 other Chevy Specialists are ready to help you

JustAnswer in the News:

 
 
 
Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.
 
 
 

What Customers are Saying:

 
 
 
  • I was having a terrible problem with the wheel bearings on my 98 Chevy Cavalier and I suspect that using this website saved me plenty of time and money. Todd L Rochester NY
< Last | Next >
  • I was having a terrible problem with the wheel bearings on my 98 Chevy Cavalier and I suspect that using this website saved me plenty of time and money. Todd L Rochester NY
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C. Freshfield, Liverpool, UK
  • This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!! Alex Los Angeles, CA
  • Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult. GP Hesperia, CA
  • I couldn't be more satisfied! This is the site I will always come to when I need a second opinion. Justin Kernersville, NC
  • Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around. Esther Woodstock, NY
  • Thank you so much for taking your time and knowledge to support my concerns. Not only did you answer my questions, you even took it a step further with replying with more pertinent information I needed to know. Robin Elkton, Maryland
 
 
 

Meet The Experts:

 
 
 
  • Tim's Auto Repair

    mechanic

    Satisfied Customers:

    7641
    Have owned a repair shop for 25 yrs.
< Last | Next >
  • http://ww2.justanswer.com/uploads/TI/tim37857/2011-10-28_23053_S6301814.64x64.JPG Tim's Auto Repair's Avatar

    Tim's Auto Repair

    mechanic

    Satisfied Customers:

    7641
    Have owned a repair shop for 25 yrs.
  • http://ww2.justanswer.com/uploads/DT/dt69nova/2012-6-15_234154_pic1.64x64.jpg Dave Nova's Avatar

    Dave Nova

    Chevrolet Technician

    Satisfied Customers:

    6870
    ASE Master Certification. GM World Class Certification
  • http://ww2.justanswer.com/uploads/ggrote1/2009-06-27_031011_me.jpg Gary's Avatar

    Gary

    Chevy Technician

    Satisfied Customers:

    5404
    15 years GM master tech
  • http://ww2.justanswer.com/uploads/testedtuff/2009-09-26_170108_pictures.jpg John's Avatar

    John

    Master A.S.E Automotive technician

    Satisfied Customers:

    4071
    A.S.E MasterTechnician A1-A8 w/L1,38 years experience General Motors Master Technician
  • http://ww2.justanswer.com/uploads/RO/rodcuda/2011-7-25_224114_Donhoff1.64x64.JPG Neal's Avatar

    Neal

    Chevy Mechanic

    Satisfied Customers:

    2306
    Shop Owner and Mechanic on multiple makes.
  • http://ww2.justanswer.com/uploads/goodwrench9124/2008-11-09_220838_dscf0007.jpg goodwrench9124's Avatar

    goodwrench9124

    ASE Certified Technician

    Satisfied Customers:

    2041
    Ase Master Certified, GM Master Certified Tech. Awarded GM Top performer, Hybrid certified
  • http://ww2.justanswer.com/uploads/DR/drivefast1971/2012-1-12_172422_0009051tQKh.64x64.jpg Ron Z.'s Avatar

    Ron Z.

    - Chevy Tech -

    Satisfied Customers:

    1912
    18+yrs experience. State Inspector and Chevy Diagnostics