Neutral safety backup switch or park neutral position switch provide the tcm with signals to indicate selected gear range.
Allison transmission neutral safety switch problems.
You should understand there is a problem if you cannot see the d light up on your gear indicator.
I am currently having some problems with mine including diagnostic codes p1711 and p1713.
I have found a tsb 02 07 30 011c that seems to cover my problems.
Some of the symptoms of failure include but are not limited to no start condition gear shift indicator on dash not following properly trans stuck in limp mode or fail safe dtc s set indicating pressure switch codes this switch easily installs with just common hand tools.
Descriptionone of the most common problems with the allison transmission is failure of the neutral safety back up switch.
If the d doesn t light up on your gear indicator this could be the issue.
This switch is the dual plug style that can be found on any 01 05 lb7 or lly.
It is part number 29540479.
The purpose of the neutral safety switch is to prevent the car from starting while in gear which would cause it to launch forward unexpectedly.
One of the most common problems with the allison transmission is failure of the neutral safety back up switch.
Our school has a 2007 ih bus with dt466 and 2500pts allison trans.
Here the culprit is often the neutral safety backup switch.
Trying that tomorrow as it is a 50 part.
When i arrived at the bus it would not start due to a suspected neutral safety switch issue.
Neutral safety backup switch issues are another common allison transmission problem on the gm duramax versions.
The neutral safety switch is a safety device that only allows you to start your engine when the automatic transmission is in either park or neutral.
It developed a problem on route yesterday and would no longer drive the bus.
I have a p n 29541852 1 connector.
I suspect neutral safety backup switch as they do get crudded up and i haven t put back my fenderwells since other work.
Allison transmission 29540479 nsbu switch kit 2001 2005 lb7 lly 5 speed 2 plug.
Input speed sensor provides the tcm with a signal to measure the rotating speed of the turbine shaft from which it can calculate transmission rpm and slip.
After jumping across the solenoid and getting the engine started the bus had both forward and reverse movement.
Has anyone here had to have their park neutral safety switch replaced on their allison transmission.
