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pickup is throwing more codes than ive ever seen. It was fine then I stopped yesterday to put on fuel and after I left I got a CEL and the (!)BRAKE light started flashing along with the trans temp kept going blank and coming back up and if I put it in manual mode the gear selection would disappear as well and these 3 things occurred at the same time and after a few mins the trans went into 3rd gear and stayed there till I got home. and every time these lighted up I could hear a funny clicking noise coming from the under dash/petal area. I also know my cruise control/brake switch is been giving me problems I have to move the petal around to get cruise to engauge. I plugged in my scanner and i'm getting these codes..

P0848
P0834
P0658- actuator supply voltage A circuit low
P0757
PO071- Trans temp sensor circuit signal high
U0073- control module communication bus off
U0100-Lost communication with ecm
P2730-PC solenoid control circuit high voltage
P2764- (cant read my writing but it looks like) TCC Pcs solenoid control circuit low
P0873 - Trans pressure switch solenoid E circuit High
U0140- Lost communication with body control system
u0073- control module communication bus off
u0100 lost comm w/ ecm/pcm

I can clear the codes and get it in either forward or reverse but if I take it outta that gear it wont move and says shift range inhibited and I have to clear codes restart and do it again. It also shifts real hard in the forward gears if I try to drive like this.

I put the truck on the hoist and checked the harness going in the trans and no noticeable wires are cut I wiggled the plug around a little and then checked the harnesses in the engine compartment again I wiggled them a little and still nothing. I then checked fuses on the ecm ones and trans fuses and they all checked out good.

I have not checked the oil level but it was good last week when I changed the engine oil and the spin on filter is getting old now as well.

To me I feel this could be an electrical/ground problem I had my scanner and checked voltage and it says batteries are good and alternator is charging normal voltage. I have a newer snap on diagnostic scanner.

wondering if anyone knows where to even start looking for problems on this..

2009 2500 efi live 70hp tune been running this for 2 years now no dpf
 

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Discussion Starter #2
went out this morning and checked the oil and the level was good at 175 trans temp i then cleared the codes and drove it around my house and i pulled these codes.
p2727
p2729
p2761
p0708
p0843
p0848
p0873
p0657

most these are to do with circuit voltage either high or low if i remember right so this brings me to think electrical problems again but where to start looking...
 

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Have your batteries load tested. A weak battery can cause all sorts of mayhem with our trucks. You may have to check for parasitic draws on your system. Sometimes, after long runs, the batteries will test fine, but short stops can run them down if they are marginal. I've had all sorts of weird messages with weak batteries, including the transfer case going to neutral for a few seconds when driving. The only thing we can put it off to was low capacity batteries.
 

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May be a long shot, but could try you ignition switch. I had my tranny do all kinds of crazy stuff and could not figure it out for a while. It's inside the column, not the key and barrel. The ignition switch is what sends power to your tcm from my understanding, and if there is bad continuity, it can play all sorts of Havoc with your tcm. My truck would not go into reverse, and would start our from a stop in 5th gear and then gradually down shift. May be totally different with a nbs truck though.
 

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pickup is throwing more codes than ive ever seen. It was fine then I stopped yesterday to put on fuel and after I left I got a CEL and the (!)BRAKE light started flashing along with the trans temp kept going blank and coming back up and if I put it in manual mode the gear selection would disappear as well and these 3 things occurred at the same time and after a few mins the trans went into 3rd gear and stayed there till I got home. and every time these lighted up I could hear a funny clicking noise coming from the under dash/petal area. I also know my cruise control/brake switch is been giving me problems I have to move the petal around to get cruise to engauge. I plugged in my scanner and i'm getting these codes..

P0848
P0834
P0658- actuator supply voltage A circuit low
P0757
PO071- Trans temp sensor circuit signal high
U0073- control module communication bus off
U0100-Lost communication with ecm
P2730-PC solenoid control circuit high voltage
P2764- (cant read my writing but it looks like) TCC Pcs solenoid control circuit low
P0873 - Trans pressure switch solenoid E circuit High
U0140- Lost communication with body control system
u0073- control module communication bus off
u0100 lost comm w/ ecm/pcm

I can clear the codes and get it in either forward or reverse but if I take it outta that gear it wont move and says shift range inhibited and I have to clear codes restart and do it again. It also shifts real hard in the forward gears if I try to drive like this.

I put the truck on the hoist and checked the harness going in the trans and no noticeable wires are cut I wiggled the plug around a little and then checked the harnesses in the engine compartment again I wiggled them a little and still nothing. I then checked fuses on the ecm ones and trans fuses and they all checked out good.

I have not checked the oil level but it was good last week when I changed the engine oil and the spin on filter is getting old now as well.

To me I feel this could be an electrical/ground problem I had my scanner and checked voltage and it says batteries are good and alternator is charging normal voltage. I have a newer snap on diagnostic scanner.

wondering if anyone knows where to even start looking for problems on this..
pickup is throwing more codes than ive ever seen. It was fine then I stopped yesterday to put on fuel and after I left I got a CEL and the (!)BRAKE light started flashing along with the trans temp kept going blank and coming back up and if I put it in manual mode the gear selection would disappear as well and these 3 things occurred at the same time and after a few mins the trans went into 3rd gear and stayed there till I got home. and every time these lighted up I could hear a funny clicking noise coming from the under dash/petal area. I also know my cruise control/brake switch is been giving me problems I have to move the petal around to get cruise to engauge. I plugged in my scanner and i'm getting these codes..

P0848
P0834
P0658- actuator supply voltage A circuit low
P0757
PO071- Trans temp sensor circuit signal high
U0073- control module communication bus off
U0100-Lost communication with ecm
P2730-PC solenoid control circuit high voltage
P2764- (cant read my writing but it looks like) TCC Pcs solenoid control circuit low
P0873 - Trans pressure switch solenoid E circuit High
U0140- Lost communication with body control system
u0073- control module communication bus off
u0100 lost comm w/ ecm/pcm

I can clear the codes and get it in either forward or reverse but if I take it outta that gear it wont move and says shift range inhibited and I have to clear codes restart and do it again. It also shifts real hard in the forward gears if I try to drive like this.

I put the truck on the hoist and checked the harness going in the trans and no noticeable wires are cut I wiggled the plug around a little and then checked the harnesses in the engine compartment again I wiggled them a little and still nothing. I then checked fuses on the ecm ones and trans fuses and they all checked out good.

I have not checked the oil level but it was good last week when I changed the engine oil and the spin on filter is getting old now as well.

To me I feel this could be an electrical/ground problem I had my scanner and checked voltage and it says batteries are good and alternator is charging normal voltage. I have a newer snap on diagnostic scanner.

wondering if anyone knows where to even start looking for problems on this..

2009 2500 efi live 70hp tune been running this for 2 years now no dpf

The TCM monitors inputs from several onboard systems to operate the transmission properly. If the TCM receives an input that s far enough out of range to affect transmission operation, the TCM will enter Transmission Abuse Protection Mode.

In this mode, the TCM can inhibit engagements into drive and reverse and any or all shifts, depending upon what caused the TCM to enter this mode.

What Is the TCM Monitoring?
The TCM monitors inputs from numerous sensors from several onboard systems to control the transmission operation. These sensors are:

Crankshaft (CMK) and CamshaftPosition (CMP) sensors (figures 1 and2) for engine RPM.
Throttle Position Sensor (TPS)or Accelerator Position Sensor(APPS; figures 3 and 4) forengine load.
Manifold Absolute Pressure(MAP) or Barometric Pressure(BP) sensors (figure 5) also forengine load.
Engine Coolant Temperature(ECT) sensor (figure 6) andTransmission Fluid Temperaturesensor (TFT), located in the pressure switch manifold (PSM).
Neutral Safety Backup Switch(NSBU) (figure 7) or Park/NeutralPosition (PNP) switch.
Input Speed Sensor (ISS/TSS;figure 8).
Output Speed Sensor (OSS).
Transmission Fluid PressureSwitch (PSM; figure 9).
Transfer Case Position sensor or switch (figure 10).
Let s look at each of these inputs to determine how the TCM uses them to control the transmission operation.

Crankshaft and camshaft position sensors Provide the TCM with engine RPM signals, which it uses to calculate TCC slip.

Throttle position sensor or accelerator position sensor Provide the TCM with engine load signals to calculate line pressure rise and shift timing.

Manifold absolute pressure and barometric pressure sensors Provide the TCM with engine load signals for calculating line pressure rise and shift timing.

Engine coolant and transmission temperature sensor Provide the TCM with temperature signals to allow it to determine actual operating temperatures of engine and transmission.

Neutral safety backup switch or park/neutral position switch Provide the TCM with signals to indicate selected gear range.

Input speed sensor Provides the TCM with a signal to measure the rotating speed of the turbine shaft, from which it can calculate transmission RPM and slip.

Output speed sensor Provides the TCM with a signal it can use to determine vehicle speed and calculate transmission slip.

Transmission fluid pressure switch manifold Provides the TCM with signals for monitoring clutch engagement and shift timing.

Transfer case position sensor or switch Provides the TCM with a signal to identify transfer case range.

Now let s discuss how each of these inputs can cause the TCM to inhibit transmission operation. When the TCM inhibits the transmission operation, you may notice the PRNDL display flashing on and off or display Gear Inhibited or Shift Inhibited. These conditions can cause the TCM to inhibit transmission operation.

High engine RPM on engagement Check engine RPM while shifting into gear. If engine RPM exceeds idle specifications, the TCM will keep the transmission in neutral. Check CMK and CMP inputs and idle speed adjustment; repair as needed.

High throttle or high torque on engagement If the throttle or accelerator position sensor signal exceeds 25% during transmission engagement, the TCM will keep the transmission in neutral. Check sensor input signal to TCM at idle; repair as needed.

Erratic input speed sensor signal If the TCM receives an erratic input speed sensor signal during engagement, the TCM will keep the transmission in neutral. Check input speed sensor signal; repair as needed.

Erratic output speed sensor signal If the output speed sensor signal is erratic or over 300 RPM during engagement, the TCM will keep the transmission in neutral. Check the output speed sensor signal;
repair as needed.

Erratic neutral safety backup or park/neutral position switch signals If the TCM receives an erratic signal from the neutral safety backup or park/neutral position switch, it ll keep the transmission in neutral. Check the switch signals at TCM, check wiring and connections, and check for water contamination in the neutral safety backup switch; repair as needed.

Erratic pressure switch manifold signals If the signal from the
pressure switch manifold is erratic, the TCM will keep the transmission in neutral. This may be caused by low fluid level, valve body problems, a faulty pressure switch manifold, or problems with the wiring or connections; repair as needed.

Low transmission fluid temperature If the transmission fluid temperature sensor signal indicates the transmission temperature is below -49 F (-45 C), the TCM will keep the transmission in neutral. Verify the transmission temperature. Check the transmission fluid temperature sensor circuit, wiring, and connections; repair as needed.

Transfer case in neutral when shifting transmission into gear If the transfer case control system indicates the transfer case is in neutral while shifting the transmission into gear, the TCM will keep the transmission in neutral.

If it indicates the transfer case was shifted to neutral while driving, TCM will wait until the vehicle output speed drops below 300 RPM to shift the transmission into neutral. Check and repair transfer case input to TCM as needed.

Transmission slip If TCM receives a signal that the transmission is slipping, it ll prevent the transmission from shifting into that gear range. Check transmission operation; if it seems to be working properly, check the appropriate sensor inputs. If the transmission is slipping, repair as needed.

Well there you have it: the most likely causes and possible cures for the most common problem plaguing the Allison LCT1000 transmission: inhibited shifts or gear ranges. With a better understanding of how the Allison LCT transmission group operates, you should have no problem keeping those trannys rolling
 
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