Ignition lock assemblies · key lock cylinder and tumbler set, ignition switch module with LOCK, ACC, ON and START contacts, START return spring, starter current, key interlock, steering column lock, FMVSS 114 theft protection, electronic steering locks for keyless start
An ignition lock assembly combines a mechanical key lock cylinder (the tumbler set that reads the key cut), an ignition switch module whose rotor closes the LOCK, ACC, ON and START circuits as the key turns, and, where fitted, a steering column lock that blocks the steering when the key is out. Ask three things first: which switch positions and contact loads the assembly must carry, the number of key combinations and the lock cylinder security it offers, and how it meets the theft-protection and key-interlock rules of the target market.
Key-operated ignition lock assemblies for road vehicles: the lock cylinder and tumbler set, the electrical ignition switch module fitted behind it, the mechanical steering column lock, and electronic steering column locks used with keyless start. Door and tailgate lock cylinders, remote keys, starter motors and relays are outside this page except where they affect the ignition lock.
01
In a Tokai Rika patent ignition switch, the vehicle key goes through a key cylinder into the ignition rotor, and the rotor positions start and stop the engine and switch the vehicle's electric components. The contact portion has four fixed contact points for the four rotor positions LOCK, ACC, ON and START, wired through an integral connector to the vehicle controller, and a return spring turns the rotor back from START to ON. LOCK is the position in which the engine is stopped, the electric components are off and the key can be inserted or removed. A warning switch in the rotor detects whether the key is inserted. [2]
The same switch carries a solenoid key interlock: the vehicle controller reads the rotor position and the automatic transmission shift position, and unless the shift is in park it extends a plunger that stops the rotor from returning to LOCK, so the key cannot be removed. The patent places the solenoid on the side of the switch body away from the contact portion for safety. [2]
Contact load depends on whether the START circuit feeds the starter contactor directly. Valeo's patent US 5,892,422 states that without an auxiliary relay the ignition switch has to carry a current that may reach tens of amperes, whereas about 1 ampere is enough to control the contactor through the relay, which lets the wiring and the ignition switch be dimensioned smaller. [3]
Editorial note: ask the supplier for the rated current of each circuit (ACC, IG, START) at the system voltage, the contact resistance and the electrical and mechanical life test conditions, because the reviewed sources do not state these values for a specific part.
Give the supplier the vehicle model or drawing, the switch positions and circuit list, current per circuit and system voltage, whether START drives a relay or the contactor directly, key interlock and key-in warning requirements, connector type, lock cylinder and key system, steering lock type, target market regulations and quantities.
02
Federal Motor Vehicle Safety Standard No. 114 (49 CFR 571.114) applies to passenger cars and to trucks and multipurpose passenger vehicles of 4,536 kg (10,000 lb) GVWR or less. Each vehicle must have a starting system that, whenever the key is removed, prevents normal activation of the engine or motor and prevents steering, forward self-mobility, or both. The maker must provide at least 1,000 unique key combinations per vehicle type, or a number equal to the vehicles of that type it builds, whichever is less. A key is defined as a physical device or an electronic code. [1]
The standard also requires an audible warning when the key is in the starting system and the driver's door is opened, with stated exceptions. For vehicles with a park position, the starting system must prevent key removal unless the transmission is locked in park (with tool-operated or covered override options), and the vehicle must not move more than 150 mm on a 10 percent grade with the gear selector locked in park. Vehicles built on or after September 1, 2010 with an automatic transmission must also have a brake transmission shift interlock. [1]
Huf lists a mechanical steering column lock cylinder among the components of a vehicle lock set, alongside door and tailgate cylinders and keys. Its Twin System cylinder uses tumblers that run on two crossing axes in four directions, with the key milled on all four sides of a rectangular bit; the housing takes up to ten tumblers with a freewheel feature and offers up to 80,000 locking options. [4]
Editorial calculation: 80,000 locking options is 80 times the FMVSS 114 minimum of 1,000 key combinations per vehicle type. [4] [1]
Keyless start replaces the key-driven steering lock with an electronic steering column lock. Huf states it introduced the first one in 1997; its current locks detect position with three Hall sensors, use a self-locking transmission, connect via CAN high-speed, CAN low-speed or LIN, and are offered at ASIL B (D) with one microcontroller or ASIL D with two microcontrollers under ISO 26262. [5]
03
Suppliers linked to this page list ignition lock or steering lock products; each card links to the page reviewed.
The listing reviewed covers mechanical steering column lock cylinders within vehicle lock sets and electronic steering column locks.
04
This is a functional reference built from the sources cited; it is not one maker's design.
| Part | Role | Fix in the order |
|---|---|---|
| Lock cylinder and tumbler set | Reads the key cut; up to ten tumblers in one design. [4] | Tumbler count, key system. |
| Ignition rotor | Turns through LOCK, ACC, ON, START. [2] | Positions and angles. |
| Contact portion and connector | Four fixed contacts wired to the controller. [2] | Circuits, current, connector. |
| Return spring | Returns START to ON. [2] | Return function. |
| Key warning switch | Detects key insertion. [2] [1] | Key-in warning. |
| Key interlock | Holds the key until park. [2] [1] | Interlock type. |
| Steering column lock | Blocks steering with key out. [4] [1] | Mechanical or electronic. |
05
An ignition lock assembly quotation needs values for your vehicle. The table explains each field, gives published values where a reviewed source states them, and says what to obtain from the supplier.
| Field | What it means and published values | Ask the supplier for |
|---|---|---|
| Operating Voltage (V DC) | Not stated in reviewed sources. | System voltage and range. |
| Current Rating (A) | Tens of amperes if START feeds the contactor; about 1 A through a relay. [3] | Rated current per circuit. |
| Contact Resistance (mΩ) | Not stated in reviewed sources. | Value and test current. |
| Insulation Resistance (MΩ) | Not stated in reviewed sources. | Value and test voltage. |
| Dielectric Strength (V AC) | Not stated in reviewed sources. | Test voltage and time. |
| Operating Temperature (°C) | Not stated in reviewed sources. | Range. |
| Storage Temperature (°C) | Not stated in reviewed sources. | Range. |
| Mechanical Life (cycles) | Not stated in reviewed sources. | Key cycles and test method. |
| Electrical Life (cycles) | Not stated in reviewed sources. | Cycles at rated load. |
| Torque (N·m) | Not stated in reviewed sources. | Key turning torque per position. |
| Ingress Protection | Not stated in reviewed sources. | IP code. |
| Housing Material | Not stated in reviewed sources. | Housing and cylinder materials. |
| Weight (g) | Not stated in reviewed sources. | Mass with and without key. |
| Key combinations | At least 1,000 per vehicle type (FMVSS 114); up to 80,000 in one cylinder system. [1] [4] | Combinations, tumbler count. |
06
Paste it into your enquiry below or into an email to a maker, then replace every bracket.
Switch: [positions; circuits; current per circuit; voltage] Start: [direct or via relay] Lock cylinder: [tumblers; key system; combinations] Steering lock: [mechanical; electronic; interface] Interlocks: [key-in warning; park interlock] Market: [FMVSS 114 or other rules] Quantity: [units]
These companies list ignition lock assembly products.
Lists mechanical steering column lock cylinders within vehicle lock sets, and electronic steering column locks.
Product scope checked 2026-10-11
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The Tokai Rika patent switch has LOCK, ACC, ON and START, with a spring returning the rotor from START to ON; the key comes out only in LOCK. [2]
With the key removed, normal engine start must be prevented along with steering, forward self-mobility, or both, and each vehicle type needs at least 1,000 key combinations. [1]
With an electronic steering column lock; Huf's units use three Hall sensors, a self-locking drive and CAN or LIN connection. [5]
Sources checked 2026-10-11. Sources are the US federal theft-protection standard on eCFR, a Tokai Rika ignition switch patent, a Valeo starter contactor patent and Huf product pages; values for your assembly must come from the supplier's drawing and test reports.
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