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2500HD/3500 HD Trucks & Drivetrain Discussion Forum for the 2001 & newer 2500HD/3500 Trucks, Transmissions & Drivetrain

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Old 02-16-2011, 08:38 PM
RickyD RickyD is offline
Join Date: Feb 2011
Location: McAlester, OK.
Posts: 2
Default 2001 transmission troubles

I have a 2001 Chevy Duramax 2500 4x4 that is stuck in 3rd gear and will not shift out. The codes read P0700-Trans. Control System Malfunct., P0847-Trans. Fluid Sensor Switch B Ckt. Low, P1711- Trans. Pressure Switch E stuck closed, P1713- Trans. Pressure Switch Rev. Ckt. Malfunct., P1781-Engine Torque Signal Ckt.
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Old 02-17-2011, 06:53 AM
Mark Rinker's Avatar
Mark Rinker Mark Rinker is offline
Join Date: Jun 2003
Posts: 5,813

How many miles on the unit? How has the truck/transmission been used?

Since the Allison 1000 is so dependable, there are many available in the parts yards. A full swap from a low mile salvage is the route I took when mine grenanded.

Yours might be easier to fix, if mileage and use is low. If its over 150K, I'd simply replace the unit with one <50K miles, if the plan is to keep the truck.

My replacement was ~$3500, transmission and labor installed, complete.
2011 Chevrolet Tahoe 5.3L daily driver
  • Previous owner of two 1994 6.5L K3500s, '01, '02, and '05 6.6L K2500s, '04 C4500, '06 K3500 dually, '06 K3500 SRW, '09 K3500HD SRW, '05 Denali
  • Total GM diesel miles to date : ~950K
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Old 02-17-2011, 04:59 PM
DADGLW DADGLW is offline
Join Date: Nov 2004
Location: vt.
Posts: 55

mine did the same thing last week...changed the nsbu switch..all better.......
02 gmc crew cab dmax 158456
06 gmc 3500 dump...6.0L
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Old 02-17-2011, 11:00 PM
RickyD RickyD is offline
Join Date: Feb 2011
Location: McAlester, OK.
Posts: 2
Default question about nsbu

Is the nsbu the same as the pressure switch E? We went to our chevy dealership today and we gave them the codes, we were told we would have to replace the switch E. The part only cost about $40 and they said it would be $430 for labor if they installed it. They said it's not that big of a deal, just drop the pan and it's the middle switch. Did you replace it yourself and how hard is it?
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Old 02-18-2011, 02:30 AM
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DmaxMaverick DmaxMaverick is offline
Join Date: Apr 2001
Location: CA
Posts: 11,830

The NSBU (Neutral/Start/Back up) is the external module connected to the range selector cable (gear shift cable).

Your problem is probably not the NSBU. The E switch could cause all the codes you are getting. It could also be an electrical connector/harness issue. Check all the connectors. Replacing the internal switches/solenoids is easy. Time is the cost. Servicing the Allison is simple. Once the pan is removed, most of the electrical components are easily accessible. Reassembly is straight forward. The pan gasket is reusable if it isn't damaged. Be sure to properly torque the bolts.
1985 Blazer 6.2
2001 GMC 2500HD D/A
2014 Chevy Cruze Diesel - Fabulous car, no problems at all, but sold Nov. 2016 @ 55K miles.
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