Truck not moving


Asked by May 17, 2017 at 11:38 PM about the 2001 Chevrolet Silverado 2500HD Crew Cab 4WD

Question type: Maintenance & Repair

I have a 2001  Chevy Duramax  has the Allison trans.
Wouldn't move the indicator on the dash would just flash so
changed the nsbu switch and no difference, had the tcm
flashed and reprogrammed and still nothing so I changed
the ignition switch and the truck then went into gear but
took a few seconds before it kicked in then went back to
not moving and just flashing on the dash a d help?

13 Answers


check the fuse. There are three main things that will blow the fuse; the front axle actuator, the encoder motor on the transfer case or a mechanical problem in the transfer case. First unplug the actuator and see if the fuse blows. If not the actuator is bad, If the fuse blows, unplug the motor on the transfer case. If the fuse does not blow with the motor unplugged, but does with it connected, remove the motor from the case and try again. If it still blows the fuse, the motor is likely bad. If the fuse does not blow with the motor out of the transfer case, the problem is more likely internal to the case. If it binds internally, the motor will pull too many amps and blow the fuse


Turn the vehicle on and have 2wd selected and get under the truck and tap on the shift motor on the transfer case with a small hammer or something see if it will pop out. I've seen alot of motors go bad and if you hit them they will go to working again, for a little while anyways. it could be a control issue or internal transfer case issue, but hitting the motor is best thing to start with.


Trans case is new and the 4 wheel drive works properly


How many miles on her? Do you tow a great deal?


There's only 20,000 on transfer case the t case works fine


Just a suggestion. Neutral is required for shifts in and out of low range. If it never detects neutral it wont shift. Press the 4hi button and shift R>N>D>N>R and repeat. Maybe it will catch on at some point


I tried that R,N,D,N,R,N,D about 7 or 8 consecutive times and it worked on my truck


If I unplugged my 4plug wire connector on the nsbu switch it will shit into gear but only second it's in a limp mode the transfer case has nothing to do with my problem I'm having

1 of 1 people found this helpful.

Ok, understand...this is a frustrating problem. Now I recall I had a similar problem back 10 years ago. Well, with the new NSBU switch the problem had returned, intermittently. The Chevy dealership service manager said since the "service engine soon" light goes out after the truck is warmed up he must wait until the light is on when his technician reads the computer, or they can do nothing. My problem occurred when the truck sits for over 4 days in a cold, humid climate, and I can't let the dealer have my truck to just sit for 4 or more days for the light to come on. The Chevy dealer did not have a certified Allison AT tech at that time. Now I remember them saying that the drain-back valve in the front pump is defective and must be replaced. The AT, and TC must be removed to access the front pump and replace the valve. Thank goodness GM performed that work under warranty, because they knew this is another problem with the Allison AT and had issued a TSB detailing the fix. Hope this helps!


I can get the truck to move but once I do I can't go far and it will just quit moving and the gear selection flashes but truck won't move unless I cycle the key a few times.


Check for Ground wires that are bad mostly G104 and G103 along with the wires on the outside frame drivers side by your feet. There should be 3 wires there and bolts get rusty causes all kinds of problems you will see many OBD errors and they can be related to bad grounds... Also will get REDUCED ENGINE POWER warning due to bad ground replacing parts that show up on OBD reader will not fix bad ground problems new parts will also show up as bad expensive lesson to learn. The wires I mentioned are only just a few you could have others


I disconnected the ground on the frame below the drivers feet and also the ground from the battery. I cleaned the contacts and reconnected. I had read the ground below the drivers feet is sometimes a culprit for issues similar to this.


One other thought....u changed the ignition switch.....and I would look at the ignition switch harness for some frayed wires as well.

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