No communication between TCM and PCM trans wont shift skips 1st to 4th

p07nnn codes are tranny
23 year old car, and old cars had few trannycodes
the service manual covers this, best is to get it and read it first.
so $20 is too much to pay to read it?
I WILL NOT POST 40 PAGES OF PCM SCHEMATICS HERE. EVER.
https://eautorepair.net/Marketing/Default.asp

TDC TRANSMISSION RELAY SENDS POWER TO TCM SOLENOIDS
LIKE THIS.

P0753 Trans 3-4 Shift Sol/Trans Relay Circs

THE SERVICE MANUAL SHOWS HOW IT WORKS
Symptom:
P-0753 TRANS 3-4 SHIFT SOLENOID/TRANS RELAY CIRCUITS
When Monitored and Set Condition: (OBD2 RULES)
P-0753 TRANS 3-4 SHIFT SOLENOID/TRANS RELAY CIRCUITS
When Monitored: Continuously with the key on.
Set Condition: This code is set if the voltage detected on the 3-4 Shift Solenoid Control
Circuit at the PCM is different than the expected voltage.
POSSIBLE CAUSES
FUSED B(+) FEED TO THE TRANS CONTROL RELAY OPEN
TRANSMISSION CONTROL RELAY DEFECTIVE " TDC
3-4 SOLENOID WIRING HARNESS INTERMITTENT DEF
3-4 SOLENOID WIRING HARNESS OBSERVABLY DEF
SHIFT SOLENOID CONTROL CIRCUIT OPEN
SHIFT SOLENOID CONTROL CIRCUIT SHORT TO GROUND
SOLENOID AND HARNESS DEF (SOLENOID CONNECTOR)
SOLENOID AND HARNESS DEF (SOLENOID CONTROL CKT)
TRANSMISSION RELAY OUTPUT CIRCUIT OPEN
TRANSMISSION RELAY OUTPUT CIRCUIT SHORTED TO GND
PCM DEF (3-4 SOLENOID/TRANSMISSION)
PCM DEF (TRANS 3-4 SOL/TRANS RLY CKT)
PCM DEF (3-4 SOLENOID CONTROL CIRCUIT)
PCM DEF (SOLENOID HARNESS AND PACK)
358
TRANSMISSION

SCHEMO BINGO.

NO TRANSMISSION OPTION TOLD AT all, your RPO list tells that..
or which engine of 3 sold new. tranny matches engine torque !
AUTO 4L80e?
manual trans NV4500;?
only clue told is won't shift
not told is auto shift fails or the shifter lever NV4500;, is dead.
the 4L80e is Tcm electronically shifted
and all USA cars this year we can scan the TCM for errors
and I bet dollars to donuts it has tranny errors.!!!
get the service manual and see how to scan the TCM.
no better way exists.
1996 up is OBD2 compliant (USA only)
some the PCM has TCM brain inside and DTC P07xx errors show up using any scan tool, but RTM

double posted same car same problem but this time a new Key clue.
what do you mean out of 4th gear.
learn the tell a drivers evidence hear,
PRNDL123,can';t move the LEVER here
or the auto trans (none told or engine or country told)
the A/t fails to up shift 3 to 4, in Drive,?
or trans is stuck in 4th drive. no matter what I do, even in Reverse I get 4th gear forward?

1: check all fuses first./
2: scan the PCM and report all DTC errors and skip none set.


shifting out of 4th gear

what does that mean, I am clueless. 4>3 down shifts fail?

Your best bet would be to take your vehicle to a ASE certified professional . You do not have the tools to diagnose this or the information.
DTC P0753
The 1-2 shift solenoid (1-2 SS) valve controls transmission fluid pressure acting on the 1-2 shift valves to position the valves for the appropriate gear. The 1-2 SS valve is a normally-open exhaust valve located on the control valve body. A fused circuit supplies ignition voltage to the 1-2 SS valve. The PCM commands the solenoid ON or OFF by switching the ground path. When the 1-2 SS valve is commanded ON, the PCM senses low voltage. When the 1-2 SS valve is commanded OFF, the PCM senses high voltage. Refer to Shift Solenoid Valve State and Gear Ratio .
If the PCM detects a continuous open, short to ground or short to power in the 1-2 SS valve circuit, then DTC P0753 sets. DTC P0753 is a type B DTC.
DTC P0753 sets when one of the following conditions occurs for 5 seconds:
Condition 1 The PCM commands the solenoid ON and voltage feedback remains high, B+.
Condition 2 The PCM commands the solenoid OFF, and the voltage feedback remains low, 0 volts.
DTC P0758
The 2-3 shift solenoid (2-3 SS) valve controls transmission fluid pressure acting on the 1-2 and 2-3 shift valves to position the valves for the appropriate gear. The 2-3 SS valve is a normally-open exhaust valve located on the control valve body. A fused circuit supplies ignition voltage to the 2-3 SS valve. The PCM commands the solenoid ON or OFF by switching the ground path. When the 2-3 SS valve is commanded ON, the PCM senses low voltage. When the 2-3 SS valve is commanded OFF, the PCM senses high voltage. Refer to Shift Solenoid Valve State and Gear Ratio .
If the PCM detects a continuous open, short to ground or short to power in the 2-3 SS valve circuit, then DTC P0758 sets. DTC P0758 is a type A DTC.
Conditions for Setting the DTC
DTC P0758 sets when one of the following conditions occurs for 5 seconds:
Condition 1 The PCM commands the solenoid ON and the voltage feedback remains high, B+.
Condition 2 The PCM commands the solenoid OFF and the voltage feedback remains low, 0 volts.
What's this p91860 , no such code .

Circuit Description
Modules that are connected to the shared communication circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have pre-recorded information about what messages are needed to be exchanged on the serial data circuits for each virtual network. The messages are usually supervised and some periodic messages are used by the receiver module as an availability indication of the transmitter module.

DTC U0401 TCM received invalid data from ECM
Conditions for Setting the DTC
The transmission control module (TCM) detects an invalid throttle position signal, engine speed signal and/or engine coolant temperature signal for more than 2 seconds.

Action Taken When the DTC Sets
• The TCM will store the DTC when a failure is detected on the first ignition cycle.
• The TCM will illuminate the HOLD lamp.
• The TCM can no longer determine the validity of any information it may or may not receive from the engine control module (ECM). Therefore the TCM substitutes default values for engine speed, throttle position, and other engine data signals.
• Transmission operation will be reduced, affecting shift points, torque converter clutch operation, and other driveability concerns.

Diagnostic Aids
• An intermittent malfunction may be caused by a fault in the electrical circuit. Inspect the wiring harness and the components for an intermittent condition. Refer to Intermittent Conditions in Engine Controls 1.6L.
• Repair any electrical circuit faults that were found. Refer to Wiring Repairs in Wiring Systems.
• Faulty ECM and/or TCM

Install a scan tool.
Turn ON the ignition, with the engine OFF.
Save the DTC and Freeze Frame information into the scan tool memory.
Perform the scan tool Clear DTC Information function for the transmission control module (TCM) and the engine control module (ECM).
Operate the vehicle for 1 minute or until the MIL illuminates.
Check the TCM for DTCs.
Is the Malfunction Indicator Lamp (MIL) On?
--
YES - Go to Step 2
NO - Repair the wiring connectors for intermittent failure

Select request DTC status from the Diagnostic Trouble Codes Information menu
Request DTC by status
Is DTC U0401 displayed?
--
YES - Go to Step 3
NO - Repair the wiring connectors for intermittent failure
3
Turn OFF the ignition.
Disconnect connector A from the TCM.
Turn the ignition ON, with the engine OFF.
Measure the resistance between terminal A17 of the TCM wiring connector and terminal K14 of the ECM wiring connector.
Measure the resistance between terminal A7 of the TCM wiring connector and terminal K15 of the ECM wiring connector.
Was the resistance the specified value for both circuits?
0 ohms
YES - Go to Step 5
NO - Go to Step 4

Are there any DTC's - diagnostic trouble codes ?in the PCM / BCM ? You have third an fourth below 50 mph but above 50 it down shifts to 2nd gear ,is this what your saying or you don't have 3rd or 4th gears at all ? Which engine did yours come with ? 2.2 L or 4.3 L You trans can set several DTC'S an not all will turn on the check engine light .
DTC B2722 (4.3 L) DTC P0218 (2.2 L) DTC P0218 (4.3 L) DTC P0502 (2.2 L) DTC P0502 (4.3 L) DTC P0503 (2.2 L) DTC P0503 (4.3 L) DTC P0705 (2.2 L) DTC P0706 (4.3 L) DTC P0711 (2.2 L) DTC P0711 (4.3 L) DTC P0712 (2.2 L) DTC P0712 (4.3 L) DTC P0713 (2.2 L) DTC P0713 (4.3 L) DTC P0719 (2.2 L) DTC P0719 (4.3 L) DTC P0724 (2.2 L) DTC P0724 (4.3 L) DTC P0740 (2.2 L) DTC P0740 (4.3 L) DTC P0741 (4.3 L) DTC P0742 (2.2 L) DTC P0742 (4.3 L) DTC P0748 (2.2 L) DTC P0748 (4.3 L) DTC P0751 (2.2 L) DTC P0751 (4.3 L) DTC P0752 (4.3 L) DTC P0753 (2.2 L) DTC P0753 (4.3 L) DTC P0756 (2.2 L) DTC P0756 (4.3 L) DTC P0757 (4.3 L) DTC P0758 (2.2 L) DTC P0758 (4.3 L) DTC P0785 (2.2 L) DTC P0785 (4.3 L) DTC P1810 (2.2 L) DTC P1810 (4.3 L) DTC P1860 (2.2 L) DTC P1860 (4.3 L) DTC P1870 (2.2 L) DTC P1870 (4.3 L) DTC P1875 (4.3 L) .
Shift Pattern This category contains the following topics:
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One forward gear only

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Two forward gears only

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Gear missing or slipping

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No upshift or slipping upshift

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No downshifts

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Non-First gear start

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Refer to First Gear Range Only - No Upshift .

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Refer to Third Gear Only .

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Refer to Second/Third Gear Only or First/Fourth Gears Only .

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Refer to Slips in First Gear .

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Refer to Slipping or Harsh 1-2 Shift .

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Refer to No 2-3 Shift or 2-3 Shift Slips, Rough or Hunting .

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Refer to No 3-4 Shift, Slips or Rough 3-4 Shift .

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Refer to No Part Throttle or Delayed Downshifts .

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Refer to Second Gear Start .

auto? tranny? JEEP WJ>
step 1 of 50
check fall fuses
the scan the PCM for DTC errors. for trans.
the FSM Cover how to check the TCM , regardless of its location.
at about 1999 most cars the TCM was moved to the ECU
and renamed, PCM. and then all TCM codes show up as
P07xx codes.
see the diag pages here, actual FSM

http://www.jeep4x4center.com/knowledge-base/index.htm?utm_source=cj#service

d flash mans, tranny fault
so scan it. us the obd2 scan tool, any and scan it.
the A/T IS VERY complex, do the tests shown in the FSM
guessing dont work
but in general (experience)
wont shift correctly dont cut it. (200 parts, and 50 was to mess up)
????
flare, skips gears, wont up shift, wont down shift, or shifts wrong speed. what gears work, what dont. just a clue and help goes get better
The tranny TCM can go to limphome mode, this mode is very clear.
and covered in the FSM and
one common failure, that happens with high mileage and poor service (not doing a flush at 50k miles)
is stuck in 1st gear, hot. only.
the ATF fluid gets more thin hot and pump output drops
this is usually a vary bad sign.
the Stall test fails.
the pump pressure test fails, hot.
there is no vacuum lines to this electronically shifted trans.
the ended back 1990(about). with old 3speeds.

scan it, could be something slimple like
the PRNDL shift switch fibbing like crazy. (common)
this car has TCM, a transmission brain.
look for OBD2 DTC errors P07xx (trans)
this TCM (part of PCM) function relies on sensor for shifting
they are:
1: TPS
2: engine INPUT rpm
3: tranny output rpm
4: shift selector.
5: ECT (engine temps)
6: ECU part of the PCM calculates load at all times and sends that to the TCM , so that TCM can down shift on hills, or upshift faster on the flat or down hill.
this LOAD feature is what replaced the VACUUM of old days.

The D light , hopefully is just a bad input (cheap)
scan it. and see, its begging for you to do that.

code p0753 refers to shift solenoid (SS) A electrical===causes--wiring---shift solenoid---ECM/TCM
I'm thinking that with the transmission upgrade and the fault code showing wiring and TCM as faulty I would be paying serious attention to the configuration of the wires in the plugs. Just because the connectors go together may not mean that the corresponding wires go to the right bits. you may have to invest in a good work shop manual for the gear boxes and trace the wiring circuits out and adjust the pins in the connectors to the right circuits.

• No 3rd or 4th gear: “3-4” clutches are worn out. R&R. The car is safe to drive (in 2) until you can get it fixed.
• Trans shifts into gear harshly, car feels sluggish off the line, No 1st, 4th or TCC lockup available, Manual 2nd, 3rd and Reverse are only available gears, CEL is on: Transmission is either in limp-home mode or has lost electrical power. If there are lots of error codes in the PCM, check the under hood fuse that powers the transmission, and if it pops again, look for a short in that circuit like an O2 sensor harness touching exhaust. Otherwise, check PCM codes for a particular fault in the transmission causing the PCM to put it in limp-home mode.
• No 1st or 4th available; trans shifts 2nd to 3rd by itself in D or OD and locks the converter : Shift A solenoid failed. Easy fix in the pan. Or a wiring problem from PCM to trans.. or PCM.

Check to see if your transmission is in the limp mode, which would only give you 2nd, 3rd and reverse gears. No 1st or 4th gear.