The MLPS or manual lever position sensor is one of the vitally important inputs to the transmission control unit (TCU) of a vehicle
with modern computerized automatic transmission. Every car made in
the last 50 years has a switch similar to an MLPS. The names range from
MLPS, to inhibitor switch to neutral safety switch.
Originally called a neutral safety switch when introduced to the
automotive field because it's only duties were to make sure the car only
start in neutral and park, and to activate the reverse lights when you
shift into reverse.
As automatic transmissions became more technically advanced the MLPS
duties increased. Now the MLPS or inhibitor switch is a key input to the
TCM and ECM on every modern car I can think of. In fact, the switch,
whatever name you call it has a great deal to do with controlling what
gear your automatic transmission is in and how it shifts, and when the torque converter locks up
, as well as it's original duties.
In most cases the switch is located on the side of the transmission,
essentially hooked to the shift lever in the car. That way when you move
the lever, itâ moves the switch to the appropriate gear range. some
cars have a remote mounted switch, however the responsibility remains
On transmissions with a side mounted switch, GotTransmissions.com
often provides a new switch with their rebuilt transmissions where
failure's are more prevalent. If it is not included with the
transmission, it is a good idea to scan the car before any transmission
work is done to make sure that did not cause the problem. At my shop, we
almost always changed every one when we did a rebuild on a
transmission. Either way, I would advise putting a new factory MLPS on
your car if you do have to exchange a worn out transmission for a
rebuilt transmission, unless it is cost prohibitive.
Most of the time when an MLPS goes bad, you will know you have
something wrong with it. This is the time toâ have it checked by a
qualified transmission mechanic at a competent transmission shop.
Many folks who own affordable hand held code readers
can find out what the problem is before hand. In many cases if you are
mechanically handy you can change it yourself. If you choose to take
that route. don't forget to clear the code and re-drive the vehicle and
recheck to make sure you cured the problem.
These particular switches are on the outside of the car as we
mentioned earlier and are exposed to the road elements. Therefore
causing a hi rate of failure. Geographically speaking, problems can
occur from salt being used to melt snow in the north to water damage
from a heavy rain.
Don't forget to properly maintain your transmission on a regular basis. Feel free to sign up for our GotTransmissions.com blog
for free. You may find more money saving and drive-ability tips in your mailbox regularly.
Hope that helps