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Discussion Starter · #1 ·
sons truck, 07 lbz . second time this has happened in the last year. The first time the dealer replaced all of the shift solenoids and it was fine. He was driving fine and he was stopped for a minute in park, went back into drive selector blinks after 3-4 seconds and displays "shift range inhibited". No codes.

It will move very little in D slipping bad.no reverse at all. Snap-on scanner shows it shifting through all gears. When it goes into reverse the scanner shows it go into R for 3-4 seconds and then it goes into neutral.

had to tow home. changed both filters, fluid (level is perfect). Changed ignition switch. voltage was a little low (11.2 -11.4) still the same issues. disconnected the batteries for 10 min. Also cleaned the ground on the LF cab mount.

Also checked the connections and ground to the tcm all seem clean and tight.

what next?
 

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Hard to believe there is "NO CODES" . Most cheap scanners will not read trans codes-but the Snap-on scanner should. Solenoids do not usually go bad on an Allison--BUT stuck valves do-! [E shift valve-?]

Here is some info-
Circuit/System Description

The pressure switch manifold (PSM) is a multiple switch assembly made up of 3 normally open (N/O) pressure switches and 1 normally closed (N/C) pressure switch. Pressure switch 1 (PS1) monitors shift valve 1 positioning, pressure switch 2 (PS2) monitors shift valve 2 positioning, pressure switch 3 (PS3) monitors shift valve 3 positioning, and pressure switch 4 (PS4) monitors the position of the manual selector valve. The pressure switches communicate the positioning to the transmission control module (TCM). The position of the shift valves 1, 2, and 3 is controlled by 3 normally closed shift solenoids. When energized, SS1 directs fluid pressure to shift valve 1, SS2 directs fluid pressure to shift valve 2, and SS3 directs fluid pressure to shift valve 3, which strokes the shift valves. When the shift valve is stroked, an exhaust passage is blocked and fluid pressure to the normally open PS1, PS2, or PS3 increases. When the selector valve is in neutral or any forward position, an exhaust passage is blocked and fluid pressure to the normally closed PS4 increases.

Conditions for Running the DTC

Condition 1

•The test is enabled after engine start-up and runs as part of the transmission hydraulic initialization.
•The transmission fluid temperature is greater than -25°C (-13°F).

Condition 2

•The engine speed is less than 1000 RPM.
•The transmission turbine speed is less than 1000 RPM.
•The output speed is less than 200 RPM.
•Commanded gear is neutral, reverse or first.
•The transmission fluid temperature is greater than -25°C (-13°F).

Conditions for Setting the DTC

Condition 1:

•At start-up, all pressure switches do not indicate pressure.
•Engine speed is greater than 500 RPM for 6 seconds or 400 RPM for 15 seconds.
•The selected range is not neutral or park for 4 seconds.

Condition 2:

•Any 2 of the PS1, PS2 or PS3 switches indicate that the corresponding shift valve was stroked and a loss pressure is indicated.
•Transmission turbine speed is greater than 400 RPM.
•Transmission output speed is less than 80 RPM.

Action Taken When the DTC Sets


•DTC P0701 is a Type C DTC.
•Range is inhibited, and the driver is required to use the gear selector to re-select the range.

Conditions for Clearing the DTC

DTC P0701 is a Type C DTC.

Diagnostic Aids


•A plugged control main filter may cause the DTC to set.
•A cracked internal suction filter tube or damaged tube seal may cause the DTC to set.
•A stuck lube regulator valve may cause the DTC to set.
•Must attempt to select range in order to experience a condition.
•May have to wait several hours prior to restarting vehicle to experience the condition.
•This DTC is most likely the result of no pressure and not wiring or the pressure switch module.
 

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Discussion Starter · #4 ·
any one else have any ideas ?I have swapped the like solenoids with each other. nothing changed. the snap-on scanner shows pressure on in ports 1,2,3 on start up. the IMS shows the selector reading the proper gear on the scanner. transfer case shifts ok.
 

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Subscribing to this. My 09 LMM is having similar issues.
 

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Discussion Starter · #6 ·
I wanted to follow up on this issue. I removed the valve body and separated it. I ended up finding a roughly 3/4 inch piece of cellophane/plastic wrap inside one of the passages in the separator plate near the psc1 valve. I cleaned everything spotless and reassembled everything. Did a relearn and it shifts fine.
 

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I wanted to follow up on this issue. I removed the valve body and separated it. I ended up finding a roughly 3/4 inch piece of cellophane/plastic wrap inside one of the passages in the separator plate near the psc1 valve. I cleaned everything spotless and reassembled everything. Did a relearn and it shifts fine.
Was your spin on filter wrapped in plastic cellophane. Seen this happen before.
 
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