Ignition Switch with Key
Once you are all buckled up, mirrors adjusted and ready to go, the next step
is to
start the vehicle,
this all begins with the ignition switch. Where you insert the key is not actually
the ignition switch, it is called the tumbler assembly, and the electrical switch
is a separate piece. In this article we will explain the difference, and hopefully
answer any questions you may have about the switch-tumbler assembly. The key tumbler
is where the security aspect comes into play. An automotive
ignition key tumbler works
just like any other tumbler assembly, the key pushes up a particular set of pins
allowing the key to turn and activate the
electrical system. Some
automotive key tumblers integrate extra security measures in the form of chip coded
keys that are read by a sensor in the tumbler assembly.These keys provide an added layer of security against theft by shutting the
computer or particular
vital systems (
fuel pump,
ignition system) down unless
the proper key is inserted into the tumbler. These keys have to be copied by a special
machine that programs the chips. Some manufacturers combine the tumbler and switch
assemblies into one piece, these styles are usually the dash mounted type of ignitions
while the column mounted ones use a rod and rack assembly to activate the electrical
switch which is mounted on top of the steering column under the dash. Newer vehicles
have pretty much abandoned the lower column mount switch in favor a multi service
turn signal switch that is mounted
directly behind the tumbler assembly on the upper column. This design eliminates
several moving parts for added durability and easier replacement.The ignition switch is what powers up the key components of your vehicle, from
the computer PCM (Powertrain
Control Module) to the BCM (Body Control Module), and in some cases the TCM (Transmission
Control Module). The
starter
or starter relay gets its trigger signal from the ignition switch as well. When
the ignition switch has an issue it can cause a wide variety of symptoms. When you
consider how many things it controls the power of, it is no surprise that this one
switch can cause a transmission
to not shift or the
vehicle to simply
not start. As the ignition switch in your vehicle gets older, the contacts inside
it can become corroded or dirty causing poor continuity, this can cause the vehicle
to crank hard or possibly even set faulty
trouble
codes in the control modules due to low circuit voltage.
If it has been determined that the ignition switch in your vehicle needs to be
replaced (electrical) you should consult an automotive
repair manual for
any special procedures that need to be taken to ensure a proper
repair and no injuries to the person working
on it. As far as replacing the tumbler assembly, the steering wheel needs to be
removed (Column mount ignition), this may require disarming and disabling of the
SRS (
Airbag system),
and for this you will also need to consult a
service manual for
the proper procedure, otherwise serious injury could occur. For replacement of dash
mounted assemblies, the SRS system may not need to be disarmed, but you should consult
a repair manual to verify that for your particular vehicle. Regardless of which
type of switch your vehicle has, you should always use OEM (Original Equipment Manufacturer)
parts or the equivalent. Cheaper electrical parts tend to use lower quality materials
in the contacts which can cause them to be unreliable and not last as long as the
higher quality parts. If further technical assistance is needed,
ask our team of certified car repair technicians.
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