K 3500 Truck 4WD V8-6.6L DSL Turbo VIN 1 (2001)
Important:
The Transmission Control Module (TCM) and or the Pressure Switch Manifold (PSM) should NOT be replaced unless properly diagnosed. They are
probably not the cause of the concern. It is often assumed the module is the cause of the concern when, in fact, it is another component or the wiring
between the components that causes the concern.
Important:
Remember, everything starts with a properly operating Neutral Start Back Up (NSBU) switch. The NSBU switch has been incorporated into what is
now called the Park Neutral Position (PNP) switch. If the PNP switch does not provide the proper voltage signal to the module indicating the
transmission is in either Park or Neutral, the module will not allow the starter operation. After the engine is started, and the shift lever is moved to
either Reverse or one of the drive positions, the range selected portion of the PNP switch portion provides a voltage input to the module as to what
range the driver has manually selected for transmission operation. The module then controls pressures, shift points and other transmission functions
based on the voltage input received from the range portion of the PNP switch.
The technician may find one or more of the following conditions. The list of these conditions does not imply any type of frequency or order. They are
random events and may occur in any order.
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DTC P0708, Neutral start/backup (PNP or NSBU) switch
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DTC P0847, Pressure Switch Manifold (PSM)
^
DTC P0872, Pressure Switch Manifold (PSM)
^
DTC P0875, Pressure Switch Manifold (PSM)
^
DTC P1711, Pressure Switch Manifold (PSM)
^
DTC P1713, Pressure Switch Manifold (PSM)
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DTC U1000, Serial Data Communications
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Blank PRNDL Display
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Flashing PRNDL Display
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Slow or No Engagement of Automatic Transmission
Blank PRNDL Display
A blank PRNDL display may indicate a condition with the PNP switch and/or one or more of the four signal circuits from the PNP to the TCM.
1.
Pin A, Circuit 771 (BLK/WHT)
2.
Pin B, Circuit 773 (GRA)
3.
Pin C, Circuit 776 (WHT)
4.
Pin D, Circuit 772 (YEL)
Or, a blank PRNDL display may also occur if an out of line condition exists with the Serial Data Circuit (CKT 2470, yellow wire) from the TCM to
Splice Pack 205.
Diagnostic Tip
1.
Connect the Tech 2(R) to the vehicle.
2.
Power up the Tech 2(R).
3.
Does the Tech 2(R) communicate with the TCM? If not, inspect the serial data circuit, CKT 2470 (Yellow wire), between the TCM and Splice
Pack 205. Specifically inspect connector C106, a five terminal connector located below the left side underhood bussed electrical center, directly
beneath the red battery cable terminal connection. Perform a mating terminal pull test on all of the terminals in this connector. Repair as required.
4.
Observe the Gear Selected screen on the scan tool. The following values should be shown on the Tech 2(R) display and the vehicle's instrument
panel cluster (if equipped with the I/P display).
^
"8" (shifter should be in the Park position)
