What does shift range inhibited mean?
When it malfunctions, it may send a signal “Shift Range Inhibited”. which means the TCM got confused, or it received information different than what it expected. This may be caused by a bad switch or a loose or damaged wire.
What would cause an Allison transmission to not shift in gear?
pressure switch manifold is erratic, the TCM will keep the transmission in neutral. This may be caused by low fluid level, valve body problems, a faulty pressure switch manifold, or problems with the wiring or connections; repair as needed.
How do you fix inhibited range?
Turning it Off. This fix is the most common way to fix range inhibited Freightliners. All you need to do is turn off your Freightliner engine and turn it back on. It is a simple way to reset the operation of your transmission system and get your vehicle back to the road.
How do I reset my Allison shifter?
Allison Transmission Transmission Service Indicator Light Reset
- To reset the service indicator light.
- Turn the key on, do not start the engine.
- Move the shift selector to N-D-N-D-N-R-N, pausing briefly (less than 3 seconds) between each selector movement.
What is Nsbu switch?
The neutral safety back up, or NSBU switch) is another component that is associated with the column shifter, only it is mounted on the selector shaft of the transmission. This switch transmits the current selector position information to the transmission control module.
What’s range inhibit mean?
Range inhibit usually means the tranny thinks the engine RPMs are too high (or low) to safely shift, so itlimits what can be done. That often means the sensor has gone bad or a wire come loose, as in Al’s example.
How do I know if my Nsbu switch is bad?
When diagnosing an NSBU switch failure, you are going to want to look for these common symptoms:
- 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.
What kind of transmission does Allison make?
Allison Transmission’s 3000 Series is designed for medium-duty commercial vehicles and is engineered to adapt and operate efficiently in a variety of applications. The 3000 Series includes close or wide ratio gearing and a maximum rating of 336 kW (450 hp).
Is there a service manual for the Allison 3000 and 4000 transmission?
This manual provides troubleshooting information for the 3000 and 4000 Product Families Transmissions. Service Manuals SM4013EN and SM4014EN, plus Parts Catalogs PC2150EN and PC2456EN may be used in conjunction with this manual. • Description of the 3000 and 4000 Product Families Allison 4TH Generation Electronic Control system.
What’s wrong with Allison’s LCT transmission group?
In this issue of Keep Those Trannys Rolling, we’re going to look at one of the most common problems plaguing Allison’s LCT transmission group: inhibited gear ranges or shifts. These conditions are usually a result of the Transmission Control Module (TCM) receiving incorrect inputs from onboard sensors.
How many shift positions are on a Allison 4th generation?
3000 AND 4000 PRODUCT FAMILIES TROUBLESHOOTING MANUAL—ALLISON 4 th GENERATION CONTROLS The lever shift selector can have as many as six forward range positions (seven for the 7-speed models), as well as R (Reverse) and N (Neutral).