Managing Power Accessories
Once considered luxury items, power accessories are now standard equipment and are often damaged in collisions.Power accessories are installed on most of today’s vehicles, and assessing their damage early on can help speed up the repair process.Repair vs. replace
With the exception of wiring, very few components in power accessories can be repaired. Damaged parts will usually need to be replaced with either new or recycled parts. While the practice of using recycled parts has been common in the past, care must be taken to assure long-term satisfaction when selecting them.
With the exception of wiring, very few components in power accessories can be repaired. Damaged parts will usually need to be replaced with either new or recycled parts. While the practice of using recycled parts has been common in the past, care must be taken to assure long-term satisfaction when selecting them.
1. Door shells contain window mechanisms, door lock actuators, wiring and often the controllers. All of these should be inspected during repairs.2. Window mechanisms are complex and somewhat fragile devices. Attached to the door shell, they are quite durable. When the door shell is bent in a collision, they are easily damaged.3. This track is twisted and not serviceable.4. Window motors and gear drives should be inspected for physical damage and operation.What were once marketed as luxury convenience items are now listed in the fine print under ‘standard equipment.’ The list includes door locks, power windows, multiple power adjustments on seats and electric mirrors. Other electrically powered items include sunroofs and convertible tops, sliding doors on minivans, power lift gates and trunk lids that go both up and down. Many of these features also include obstacle interrupt features so that a hand left in the opening does not get crushed; and manual override, so that if the power fails, the door still operates easily. Rear windows on vans that are hinged at the front can now be opened with the push of a button. Electric devices offer great flexibility because they can be located almost anywhere and are easily controlled from multiple switch locations as well as by microprocessor. Designers have the ability to turn control of rear seat windows off so the kids can’t get in trouble, automate seat control systems and rear view mirrors with memory functions, and make spoilers that change position with speed. Vehicle owners have come to demand many of these formerly luxury or convenience items in the vehicles they buy. They will also expect them to work when they pick their vehicles up following repairs.How they work
More traditional vacuum pots are still used in many heating, ventilation and air conditioning (HVAC) applications. They house a diaphragm in a sealed container so pressure pushes on the flexible membrane when a valve is opened. The membrane has an actuator rod attached which moves in or out of the housing with the movement of the membrane. This rod is used like that of a solenoid to do whatever mechanical work is needed. Small, affordable electric motors and solenoids offer engineers attractive design options for all of these systems. A solenoid is a motor that moves a metal mass when electrical current generates a strong magnetic field. This motion is used to directly actuate a device, such as a door lock. Small electric motors are used with gear sets of various sorts to multiply the torque available. These may be simple, square shoulder-threaded screws used for linear actuators, which may be more efficient than a solenoid. More complex gear sets may be used to move actuator arms, drive belts or cables. Common sense diagnostics
Diagnosing problems with such systems should always start with the obvious. Subtle or complex problems may require vehicle-specific information with exact diagnostic procedures, but visual inspection will reveal many of the common problems encountered daily in collision repair shops. Operate all controls and observe their functions and all possible options. When you push the button, what happens? Does the window go up and down from both the driver’s control panel and the switch on the door? As obvious as this seems, it deserves comment. Watching a window, seat or mirror move a little is not sufficient. Particularly in collision repair, full range of motion should be tested. A broken tooth, bent track, or other part obstruction may not be revealed with partial movement. Wiring is particularly vulnerable to being crushed, stretched or cut by damaged sheet metal. Examine all wiring for cuts and abrasions. Look at the position of components. Is it possible that the wiring was stretched during the collision? While plastic insulation stretches quite a bit, copper does not. This means wire may be broken inside of the insulation. Are there marks on the motors indicating possible internal damage? Is the motion of the seat or window smooth and even, or does the speed of movement change across the full range of travel? As with all mechanical components involved in a collision repair, wear and tear are issues to be separated from the damage sustained in the accident. If evidence of wear in a system or mechanism is found, inform the customer. Taking it part by part
Motors: If you are using recycled parts, check the resistance of the original motor, or a good one from the opposite door, and the replacement part. If the resistance of the replacement motor is lower than that of the original, it has internal shorts and should not be used. Recycled parts that have been exposed to the elements may have corrosion problems.
Brackets and mounts: Often when a power accessory ceases to work properly the problem is with the mechanical aspects and not the power function. A seat motor that doesn’t move the seat may be working against too great a load because of a bent bracket that is causing a twist in the seat track. The motor mount for the window may be out of position because of inner quarter damage, resulting in a bind in the actuator arm. To test this during tear down, operate the motors when they are taken off of the vehicle. If the mechanism works well as a loose part, it should function when installed in a new or repaired door shell.
Wiring: Wiring may be cut in the door shell or hinge pillar. Again, common sense will help during the inspection process. Looking at the vehicle damage and where the wiring is located will indicate where potential problems may be. If visual inspection is not possible, it may be prudent to do continuity testing using a digital volt-ohm meter (DVOM). A repair or replace decision must be made if cut wires are found. Some manufacturers recommend wire splices be separated by 1.5 in. This will limit the possibility of repairing wiring harnesses with cuts through several wires. Wire repairs should use a crimp splice connector. This provides the most reliable connection both electrically and physically. It also seals the wiring against moisture, which could compromise the electrical connection over time.
Switches: Impact can cause damage to switches on door panels, the instrument panel and the steering column. Some systems, such as door windows, may have multiple control switches. Confirm that the windows work using all switches in all modes. Does the lock out for the back seat work? Do the door locks work from the door switches and the remote key FOB.
Controllers:Convenience features mean electronic controls. These will require vehicle-specific repair manuals to diagnose problems if obvious wire repairs do not restore all function. Check for automatic driver side window function. Do the memory functions work? Even if they have been deleted during repairs when the battery was disconnected, they should be checked to see if the system is taking commands properly.
Getting the sound right: Acoustic engineers work hard to achieve a certain sound for electric systems. Care should be taken to maintain that sound. When checking system function, listen to the sound as well. Be sure all brackets, insulators and fasteners are in good shape.Future trends
Coming to showrooms with current and future models are sophisticated sensing systems to sense if an arm is in the plane for the front door glass. This will prevent injury better than current sensors that measure the resistance of motion caused by an obstruction. Radar systems, providing proximity to surrounding vehicles and obstacles, combined with driver command sensors, such as how quickly the brake or accelerator pedal is being pushed or released, may be used to cause a series of actions designed to protect occupants in case of an accident. These may include closing windows, sunroofs, activating electric seat belt tensioners and changing seat position to help keep the passenger in place. Seat cushion sensors that determine how wide an occupant’s hips are will provide a good indication of the size and weight of the person. This will be used by the discriminating supplemental restraint system (SRS) to control appropriate air bag and seat belt tensioner actions. Inflatable seat bolsters will inflate and deflate to give additional support to the driver during high lateral acceleration and cornering maneuvers. Heated seats and steering wheels are also appearing more frequently. All of these, and other convenience features, mean more intense inspection will be required by estimators and technicians to be certain that all vehicle functions are restored after collision damage.
More traditional vacuum pots are still used in many heating, ventilation and air conditioning (HVAC) applications. They house a diaphragm in a sealed container so pressure pushes on the flexible membrane when a valve is opened. The membrane has an actuator rod attached which moves in or out of the housing with the movement of the membrane. This rod is used like that of a solenoid to do whatever mechanical work is needed. Small, affordable electric motors and solenoids offer engineers attractive design options for all of these systems. A solenoid is a motor that moves a metal mass when electrical current generates a strong magnetic field. This motion is used to directly actuate a device, such as a door lock. Small electric motors are used with gear sets of various sorts to multiply the torque available. These may be simple, square shoulder-threaded screws used for linear actuators, which may be more efficient than a solenoid. More complex gear sets may be used to move actuator arms, drive belts or cables. Common sense diagnostics
Diagnosing problems with such systems should always start with the obvious. Subtle or complex problems may require vehicle-specific information with exact diagnostic procedures, but visual inspection will reveal many of the common problems encountered daily in collision repair shops. Operate all controls and observe their functions and all possible options. When you push the button, what happens? Does the window go up and down from both the driver’s control panel and the switch on the door? As obvious as this seems, it deserves comment. Watching a window, seat or mirror move a little is not sufficient. Particularly in collision repair, full range of motion should be tested. A broken tooth, bent track, or other part obstruction may not be revealed with partial movement. Wiring is particularly vulnerable to being crushed, stretched or cut by damaged sheet metal. Examine all wiring for cuts and abrasions. Look at the position of components. Is it possible that the wiring was stretched during the collision? While plastic insulation stretches quite a bit, copper does not. This means wire may be broken inside of the insulation. Are there marks on the motors indicating possible internal damage? Is the motion of the seat or window smooth and even, or does the speed of movement change across the full range of travel? As with all mechanical components involved in a collision repair, wear and tear are issues to be separated from the damage sustained in the accident. If evidence of wear in a system or mechanism is found, inform the customer. Taking it part by part
Motors: If you are using recycled parts, check the resistance of the original motor, or a good one from the opposite door, and the replacement part. If the resistance of the replacement motor is lower than that of the original, it has internal shorts and should not be used. Recycled parts that have been exposed to the elements may have corrosion problems.
Brackets and mounts: Often when a power accessory ceases to work properly the problem is with the mechanical aspects and not the power function. A seat motor that doesn’t move the seat may be working against too great a load because of a bent bracket that is causing a twist in the seat track. The motor mount for the window may be out of position because of inner quarter damage, resulting in a bind in the actuator arm. To test this during tear down, operate the motors when they are taken off of the vehicle. If the mechanism works well as a loose part, it should function when installed in a new or repaired door shell.
Wiring: Wiring may be cut in the door shell or hinge pillar. Again, common sense will help during the inspection process. Looking at the vehicle damage and where the wiring is located will indicate where potential problems may be. If visual inspection is not possible, it may be prudent to do continuity testing using a digital volt-ohm meter (DVOM). A repair or replace decision must be made if cut wires are found. Some manufacturers recommend wire splices be separated by 1.5 in. This will limit the possibility of repairing wiring harnesses with cuts through several wires. Wire repairs should use a crimp splice connector. This provides the most reliable connection both electrically and physically. It also seals the wiring against moisture, which could compromise the electrical connection over time.
Switches: Impact can cause damage to switches on door panels, the instrument panel and the steering column. Some systems, such as door windows, may have multiple control switches. Confirm that the windows work using all switches in all modes. Does the lock out for the back seat work? Do the door locks work from the door switches and the remote key FOB.
Controllers:Convenience features mean electronic controls. These will require vehicle-specific repair manuals to diagnose problems if obvious wire repairs do not restore all function. Check for automatic driver side window function. Do the memory functions work? Even if they have been deleted during repairs when the battery was disconnected, they should be checked to see if the system is taking commands properly.
Getting the sound right: Acoustic engineers work hard to achieve a certain sound for electric systems. Care should be taken to maintain that sound. When checking system function, listen to the sound as well. Be sure all brackets, insulators and fasteners are in good shape.Future trends
Coming to showrooms with current and future models are sophisticated sensing systems to sense if an arm is in the plane for the front door glass. This will prevent injury better than current sensors that measure the resistance of motion caused by an obstruction. Radar systems, providing proximity to surrounding vehicles and obstacles, combined with driver command sensors, such as how quickly the brake or accelerator pedal is being pushed or released, may be used to cause a series of actions designed to protect occupants in case of an accident. These may include closing windows, sunroofs, activating electric seat belt tensioners and changing seat position to help keep the passenger in place. Seat cushion sensors that determine how wide an occupant’s hips are will provide a good indication of the size and weight of the person. This will be used by the discriminating supplemental restraint system (SRS) to control appropriate air bag and seat belt tensioner actions. Inflatable seat bolsters will inflate and deflate to give additional support to the driver during high lateral acceleration and cornering maneuvers. Heated seats and steering wheels are also appearing more frequently. All of these, and other convenience features, mean more intense inspection will be required by estimators and technicians to be certain that all vehicle functions are restored after collision damage.
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