Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
I have a 2004 Chevy Duramax showing a "range shift inhibit" message. While searching for a solution online, I found the part cannon method, which involves replacing the NSBU switch or ignition due to low voltage. When I check the voltage from the ignition using a scanner, it appears that the voltage is not dropping. In cases where the NSBU switch is the problem, the gear selector display will usually blink (PRND321) it not doing that and on the scanner. it's still commanding the correct gear, I'm unsure how to verify if the NSBU switch is the issue.
And there are no codes for the transmission
I haven't found anything on Mitchell that helps
As a heavy-duty diesel mechanic based in Oregon, I work on a variety of vehicles, including F-150s, tractor-trailers, RVs, pumper trailers, wood chippers, and whatever else the owner brings in.
NORMAL Inhibits Which Result in a Blinking PRNDL
• High Engine Speed NEUTRAL to Range Shifts When a NEUTRAL to DRIVE or NEUTRAL to REVERSE shift is made, when engine RPM is high, the shift will be inhibited to NEUTRAL.
• High Throttle or Torque Direction Change Shifts REVERSE to DRIVE, DRIVE to REVERSE, NEUTRAL to DRIVE, and NEUTRAL to REVERSE shifts, where throttle position is greater than 25 percent, will be inhibited to NEUTRAL.
• Four-Wheel Drive Transfer Case in NEUTRAL if the four-wheel drive transfer case is shifted into NEUTRAL while the transmission is in DRIVE or REVERSE, the transmission will continue to the commanded range until output speed is low, at which point NEUTRAL is commanded. If the driver attempts to shift the transmission from NEUTRAL to DRIVE or NEUTRAL to REVERSE, with the transfer case in NEUTRAL, the PRNDL display will blink immediately.
I did not know this information, So I thought I would share it.
I had many other trucks with connector issues at the PRNDL switch.
We sent the truck to a transmission shop, hoping they could fix it, but unfortunately, they couldn't. It's surprising how rare it is to find knowledgeable professionals in this industry. We have sent multiple trucks to dealerships and transmission shops with the hope that they would be able to fix the issues, but it seems that, on average, I know more about it than they do. And this is even though I've only been doing it for two and a half years plus schooling.
Some other technicians are throwing parts at the truck but still haven't fixed it, so it's returning to me.
I'm hoping maybe somebody sees its post and has some other ideas
As a heavy-duty diesel mechanic based in Oregon, I work on a variety of vehicles, including F-150s, tractor-trailers, RVs, pumper trailers, wood chippers, and whatever else the owner brings in.
"It's surprising how rare it is to find knowledgeable professionals in this industry. "
I know the feeling.
See my post on The 2005 Toyota Tacoma P0051 heater circuit.
I'll be messing with it today. I may try to Induce Over 10 amps , to cause a P0053. Or put the old PCM back in.
Hey bro did u ever figure this out. I'm asking because I'm having I believe the same damn issue. I have a "range shift inhibited" in my 03 lb7 only in D 3 2 1 and I got it to do it once in reverse but most the time it goes into reverse. I have the valve body off now checking everything. Already did nsbu. Keep me posted and I'll do the same. I will figure it out 100% and let u know.
We found a TikTok video discussing a specific issue related to a $4 screen in the transmission valve body. After cleaning the valve body and replacing the screen, the problem was resolved.
I'm not sure if this is the exact part number I have to go back and look, but it looks right to me
The part number m: ACDELCO 8661834 ALLISON LCT1000 VALVE BODY TCC SOLENOID SCREEN 2001-2016.
As a heavy-duty diesel mechanic based in Oregon, I work on a variety of vehicles, including F-150s, tractor-trailers, RVs, pumper trailers, wood chippers, and whatever else the owner brings in.
Thanks for the reply. I have my valve body apart right now. Also my screen was a lil dirty I'm going to clean everything very well and put my baby back together. I built my trans and knew I was gonna have a lil clutch break in debris and maybe a few lil specs from not building the trans in a nasa germ free lab environment. Hopefully all will be well after this I don't wanna take it apart and build it again but we'll see.
