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Ask DR.Cummins Your Own Question
Category: Heavy Equipment
Satisfied Customers: 3653
Experience:  16 Years working on Cummins Diesel engines,
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2010 freightliner M2 Business class with 6.8 L cummings engine

Customer Question

2010 freightliner M2 Business class with 6.8 L cummings engine, range inhibit line is on. need some direction
Submitted: 6 years ago.
Category: Heavy Equipment
Expert:  DR.Cummins replied 6 years ago.
Hello do you mean regen inhibit?
Customer: replied 6 years ago.
Range Inhibit light on the dash
Expert:  DR.Cummins replied 6 years ago.

Hi again ok you must bring the unit to the dealer so they can scan the TCM for fault codes and to properly trouble shoot.

The purpose of this indicator is to alert the operator

that transmission operation is being inhibited and that range shifts being

requested by the operator may not occur. When certain operating conditions

are detected by the TCM, the controls will command the transmission to be

locked in the range currently in use. If the torque converter clutch is applied

when the condition is detected, the clutch will be disengaged concurrently

with the activation of the RANGE INHIBIT(ED) light.

Each time the engine is started, the RANGE INHIBIT(ED) light will illuminate,

then turn off after two seconds. If the light does not illuminate during ignition,

or if the light remains on after ignition, the transmission system should be

checked immediately.

An illuminated RANGE INHIBIT(ED) light indicates the TCM has detected a condition in which directional shifts are

not allowed to be made. This inhibited state can be a self clearing

or lasting

condition depending on the amount of time the condition is present.

The following conditions may cause an inhibited state:

  • Engine speed too high
  • Throttle percentage incorrect
  • Output speed movement

The transmission control system inhibits shifting to protect the transmission

from some types of abusive operation, in response to Diagnostic Trouble

Codes (DTCs), and to satisfy transmission feature/option requirements.

These shift inhibits fall within the following types:

  • Above idle neutral to range shifts
  • Forward/reverse directional shifts
  • Transmission problems
  • Auxiliary equipment operation

Edited by DR.Cummins on 2/8/2011 at 11:49 PM EST
Customer: replied 6 years ago.

I went to the vehicle the morning and no range inhibit light on. What found was the check engine flashing and it stop. On dashboard digital display read " ECM128" can you tell what the means? Sorry I didn't get back to you yesterday.


Expert:  DR.Cummins replied 6 years ago.
128 is the componet Id.this only means there is an engine fault. Can you flash out the code via the cruise switch on and press accl/decel. Count the flashes such as @@@_@-@@ this would be fault 312
Customer: replied 6 years ago.
I tried doing this and cruse switch when I switched on the little didn't come on.
Expert:  DR.Cummins replied 6 years ago.
Ok your going to have to have the deaer scan it.check your oil and coolant levels as this make these lights come on. The unit should still have warranty
Customer: replied 6 years ago.

i'm getting software and cabling for the scanner I have, I will get back to you with code.

Expert:  DR.Cummins replied 6 years ago.
Expert:  DR.Cummins replied 6 years ago.

What codes did you get ?