Every window that goes up, every door that locks and every mirror a driver aims on a truck, bus or car starts at one part: the switch on the door armrest. It is easy to treat it as a commodity rocker, but on a modern cab it is a networked switch panel with a LIN data line, defined operating force and endurance, and a connector that has to match either a local door harness or a door control module. Getting it wrong shows up as a switch that will not drive the motor it was wired to, or a 24 V panel dropped onto a 12 V body.
This guide is the switch-side companion to the power window & door control module buyer guide. That guide covers the controller that drives the motors and where anti-pinch lives; this one covers the part the driver touches, and how a buyer picks between the three LIN door switches Youlai builds — the EDK-908, the EDK-914 and the TDK-2202/3. It assumes you know what a door armrest switch is for and are deciding which one a cab door should carry.
1. What a cab-door switch panel does
A cab-door switch panel is the driver-facing input for the cab's window, lock and mirror controls. It gathers the keys a driver reaches for (window up and down, central lock and unlock, and on a full master switch the mirror adjust, mirror select and mirror heat) into one unit at the armrest, and turns each press into a clean signal. On the Youlai LIN door switches that signal travels two ways at once: the panel has its own switching outputs so it can drive local loads directly, and it carries a LIN data line so it can also sit on the cab's low-speed network and report to a body or door controller.
That dual nature is what separates a networked door switch from a plain rocker. A LIN line runs at low bandwidth and only needs to reach the body control module (BCM) or door controller, which is exactly right for door functions where the data is small (switch state, motor direction) and the loads are local to the door. It is the same partitioning described in the Switches & Sensors technical guide: interior door, window and mirror switching runs on short hard-wire outputs and LIN, while the high-speed CAN backbone is kept for functions that need it, since a control only the door uses does not warrant its own CAN node.
2. Three LIN door switches at a glance
Youlai builds the door switch input at three points, and they are not interchangeable; they separate cleanly by system voltage and by how much of the door the panel controls. The table below is the fastest way to see where each one sits before the detail in section 3.
| Switch | System | Function scope | Drive path | Endurance / IP |
|---|---|---|---|---|
| EDK‑908 | 24 V (18–32 VDC) | Full master: window · central lock · mirror adjust · mirror select + heat | Direct outputs + LIN (local drive, or reports to door module per programme) | > 50,000 ops · IP54 |
| EDK‑914 | 24 V (18–32 VDC) | Leaner: window up/down + central lock (single- and dual-button variants) | LIN + window/lock switching (motor path direct or via module per programme) | > 50,000 ops · IP53 |
| TDK‑2202/2203 | 12 V (9–16 VDC) | Window + central lock; driver master + single-window switch set | Direct 25 A window-motor drive + LIN for lock / door coordination | 30,000 ops · interior (IP per programme) |
All three share the same LIN-plus-local-output idea and the same 5 ± 1.5 N key action, so the choice is not about switch quality; it is about matching the door. Read the table left to right: voltage first, then how much of the door the panel owns, then whether it drives the motor itself. Those three columns settle almost every case.
3. What actually decides the choice
Three parameters do almost all the work. Take them in order and the part number falls out.
System voltage is the first fork
A 24 V system (heavy trucks, buses and most construction machinery) runs the EDK-908 or EDK-914, both specified for an 18 to 32 VDC working range. A 12 V system (most passenger cars and light vehicles) runs the TDK-2202/3 set at 9 to 16 VDC. What decides this is the cab's low-voltage electrical system, not the powertrain: an electric or hybrid vehicle can be built on either 12 V or 24 V, so confirm the body-electrical voltage rather than reading it off the drivetrain. Either way it is not a preference; the motor circuit rating, the quiescent draw and the connector pinout are all set to the system voltage, so a switch built for one will not simply work on the other. Settle voltage before anything else.
Function scope decides how much door the panel owns
On a 24 V cab the second question is how much of the door the armrest controls. The EDK-908 is the full driver's-door master: window lift, central lock, mirror adjust, mirror select and mirror heat on one panel, with the window-lift keys travelling ±12°, the central-lock and mirror-adjust keys ±8°, and a short 1.8 mm mirror-select stroke; the same electrical envelope is also offered as the EDK-908B with an alternate key map, legend and connector arrangement. The EDK-914 strips that back to windows and central lock in single- and dual-button variants, for a door where a separate mirror switch handles the mirrors or the cab has no powered mirror set. Choosing the EDK-914 where the full master is not needed keeps the key count and the connector honest; choosing the EDK-908 where the door owns the mirrors avoids bolting a second switch onto the armrest.
The drive path decides whether the switch carries the motor
The last question is whether the switch drives the window motor itself or hands off to a door control module. The 12 V TDK-2202/3 master switches the window-motor circuit directly (rated to carry 25 A, with a 12 ± 0.7 A motor-stall current quoted for the motor circuit), plus a LIN line for central-lock and door coordination. This is a switch that carries current. On a 24 V cab the split is set per programme: the EDK-908 has its own window, lock and mirror outputs and can drive those loads directly on a local harness, while the EDK-914 carries the window and lock switching plus LIN but does not publish a window-motor current rating, so whether it switches the motor on its own outputs or commands a door module is confirmed against the harness. On a networked cab either switch reports over LIN to a door module that owns the drive. One honest limit worth stating up front: torque-based anti-pinch with self-learning is a module function, not a switch function; the TDK-2202's stall-current figure is a motor-circuit rating, not a force-based pinch guard.
4. Feel, travel, endurance and sealing
The parameters a driver never reads but feels every day are the operating force, the key travel and the endurance rating. All three Youlai LIN door switches use a 5 ± 1.5 N key action for a positive press that is neither mushy nor stiff. Endurance and sealing then track the platform: the 24 V EDK-908 and EDK-914 are both qualified past 50,000 operations, while the 12 V TDK-2202/3 is rated to 30,000. Read the rating against how hard the door is worked: a cab door pressed every shift is where the higher 50,000-operation count earns its place, while a passenger door that sees fewer presses over its life is well matched to the 30,000 figure.
Sealing follows the same logic. As interior door-panel controls the EDK-908 carries IP54 (dust-protected and guarded against splashing water from any direction) and the EDK-914 IP53 (dust-protected and guarded against water sprayed at up to 60° from vertical); both are rated for a protected cabin rather than direct immersion, and the TDK-2202/3 is an interior part with its sealing class confirmed per programme. Working temperature is -30 to +85 °C on the 24 V EDK parts (storage to -40 °C) and -40 to +80 °C on the 12 V TDK set, so both cover cabs that cold-soak overnight and work through hot, humid duty. None of these are the number that wins a brochure, but they are the numbers that decide whether a switch still feels right years into service.
5. Where each switch fits on real vehicles
The same door functions read the same on a spec sheet across vehicle types, but the platform decides which switch answers.
- Heavy trucks and buses (24 V). A tractor or coach cab with powered, heated mirrors and central locking on the driver's door is the classic EDK-908 case — one master panel owning windows, lock and the mirror set, reporting over LIN to a body or door controller. On a bus the driver-door switch commonly reports over LIN to a networked door module, which then coordinates with the passenger-door systems on the vehicle's wider body network.
- Construction machinery (24 V). A cab that needs its windows and central lock but has fixed or manually adjusted mirrors is a good fit for the leaner EDK-914 — the same 18–32 V LIN family without the mirror outputs, in single- or dual-button form to match a one- or two-window door.
- 12 V passenger and light vehicles. A 12 V body with a driver master controlling several windows plus central lock, and a single-window switch on the passenger doors, is the TDK-2202/3 set. Its 25 A direct motor drive suits a vehicle where the switch carries the window motor rather than a separate module doing it. On an electric or hybrid vehicle, confirm whether the body system is 12 V or 24 V first: a 24 V electric platform points back to the EDK parts.
- Doors that only raise a window. Where a single door needs nothing more than window up and down plus a lock, the single-button EDK-914 variant avoids paying for a master-switch key count the door will never use.
6. The switch and the door module are two parts, not two options
The most common mix-up in this category is treating a door switch and a door control module as alternatives. They are two halves of the same door sub-system. The switch is the driver-facing input; the module is the controller that reads switch inputs, drives the window, lock and mirror motors, carries the motor-drive protection and links to the body network over CAN. On a simple local harness a switch such as the EDK-908 can drive its loads directly and there is no separate module; on a networked cab the switch provides the controls and a module such as the EBX-2163 door & window control module owns the logic and the drive, with the split confirmed per programme. Anti-pinch and self-learning travel calibration are module functions: only the controller that drives the motor can sense a jam and reverse it. Electrical protection, though, is not exclusive to the module; the EDK-908 switch itself carries five-way protection (over-voltage, over-current, short-circuit, over-temperature and stall) on its own outputs, while the module adds the motor-drive protection on the loads it drives. For that half of the decision, dedicated module versus BCM versus switch panel and where anti-pinch belongs, see the power window & door control module guide.
7. How to write a specification a supplier can quote
A door-switch requirement a supplier can quote against, rather than guess at, covers five things. Leaving one blank is what turns a quick quote into a round of questions.
- System voltage. 12 or 24 V nominal and the tolerance band. This is the first fork: 12 V points to the TDK-2202/3 set; 24 V points to the EDK-908 or EDK-914.
- Function scope on the door. Windows only, windows plus central lock, or the full window / lock / mirror-adjust / mirror-heat master. State each function, because it sets the key count and the connector size.
- Drive path. Whether the switch drives the window motor directly (as the TDK-2202 does at 25 A) or reports to a door control module over LIN. This decides the switch's output stage and its role in the harness.
- Button layout and legend. Single- or dual-button, driver-master versus single-window, and the ISO 2575 key symbols, backlight and language for your market. This is the part most often left to "standard" and then reworked.
- Connector and pinout. The parts use different housings (an 8-way plus 10-way pair on the EDK-908, a 16-way master plus 8-way single on the TDK-2202/3, and a per-programme connector on the EDK-914), so name the target harness or ask us to confirm it against the door module.
The item buyers skip and regret is the drive path in point three. Whether the switch carries the motor or reports to a module changes the output stage, the connector and the way the door harness is drawn; deciding it after the harness is designed is expensive. Settle it with the function scope, not after.
8. What to look for in a supplier
A door switch is touched thousands of times a year, carries a LIN line onto the cab network and, on a 12 V master, switches the window-motor current itself. The supplier questions that matter are about capability and honesty, not headline price.
- Quality system in hand. Ask for the IATF 16949 certificate and what the PPAP package contains. Youlai manufactures under IATF 16949 with a PPAP package on programme handoff. Treat any verbal "automotive grade" claim without a certificate number as marketing.
- Endurance and feel testing. The 50,000-operation (24 V) and 30,000-operation (12 V) ratings only mean something if they are verified. A supplier should describe the contact make/break, operating-force and LIN-communication checks it runs, and confirm endurance on a sample basis rather than quote a number off a datasheet.
- Motor-circuit rating, where the switch drives loads. On a direct-drive master like the TDK-2202 the 25 A carry and the stall-current figure need a genuine contact and terminal design behind them. Ask how the switched motor circuit is rated and protected — and remember the stall figure is a motor-circuit value, not anti-pinch.
- Key legend and connector customisation. The switch's whole job is to fit your door, so the legend set, backlight scheme, button layout and connector are expected programme variables rather than exceptions. Ask early what a key-map or connector change means for tooling, minimum order and validation, so the cost and lead time are clear before nomination.
- Standards and EMC capability. Confirm in-house EMC pre-compliance and environmental testing rather than outsourced-only validation. Youlai validates in an in-house environmental laboratory with EMC pre-compliance equipment, and customer or destination-market standards are confirmed per project.
If you are scoping the door armrest, the most useful things to bring to a first conversation are your system voltage and your function scope from section 7 — whether the door needs the mirrors, whether the switch drives the motor or a module does, and the button layout you want. That lets us map the door onto the EDK‑908, EDK‑914 or TDK‑2202/2203, pair it with the matching door control module, or tell you honestly where a custom key map is needed. For where these switches sit among the cab's other controls, the Switches & Sensors technical guide covers the full HMI stack.
For drawings, a key-legend and connector review or a sample request against your vehicle programme, please use the contact page or message +86 134 6767 4786 on WhatsApp. Typical reply within 24 hours during China business hours (UTC+8).