What causes the TCM relay to open?

Start by looking at the fuse box... check all the fuses. Next possibility is a relay.

The Suzuki Jimny Transmission Control Module (TCM) is an electronic circuit component that controls gear shift, TCC lock-up and idle-up according to the signal from each sensor. It is a microcomputer consisting of an IC, transistor, diode, etc. It is installed behind glove box.

1. Ignition switch
2. Transmission range sensor
3. Input shaft speed sensor
4. Output shaft speed sensor (A/T VSS)
5. Shield wire
6. Vehicle speed sensor (VSS)
7. Transmission fluid temperature sensor
8. Shift solenoid-A (Shift solenoid No.1)
9. Shift solenoid-B (Shift solenoid No.2)
10. Shift solenoid-C (Shift solenoid No.3)
11. Shift solenoid-D (Shift solenoid No.4) 12. TCC solenoid (Lock-up solenoid)
13. "O/D" cut switch
14. "O/D OFF" lamp
15. Monitor connector No.2
16. DLC
17. To ECM
18. To A/C
19. To brake lamp switch
20. To main relay
21. Terminal arrangement of TCM coupler

what car.? name it? it has a name. Cherokee, wranger grand.... what/?
jeep tells, not much
automatic or manual.
some autos do have TCM box (getting rare these days)

others newer the TCM moved into the ECU and became PCM
which engine, as transmissions match engines.
and what country?> as we USA have 2 engines and others have vastly more choices.
see?
we have no idea al ALL what drive-train is in there.
ill pretend you said cherokee.
with the 4 liter engine. I6, 6 banger , INLINE
i open your FSM book and look
and here is the XJ TCM

Trouble Code: P0846

A/T 2/4 Pressure Switch Circuit Malfunction
Possible Causes:


2/4 pressure is incorrect, or internal transmission faults exist 2/4 pressure switch circuit is open, shorted to ground or power 2/4 pressure switch is damaged or it has failed TCM relay power circuit to L/R switch is open (loss of B+) PCM/TCM has failed

Trouble code P0846 means: A/T 2-4 Pressure Switch Circuit Malfunction

2/4 pressure is incorrect, or internal transmission faults exist 2/4 pressure switch circuit is open, shorted to ground or power 2/4 pressure switch is damaged or it has failed TCM relay power circuit to L/R switch is open (loss of B+) PCM/TCM has failed
This possible causes are to be checked to confirm the fault.Thats it. Thanks.

2000 TOYOTA TACOMA 2.7L 4-cyl Engine Code 3RZ-FE

Engine Oil Grade 1......API* All TEMPS......5W-30 Optional ..10W-30
Engine, 2WD, with filter..........5.5 liters
Engine, 4WD, with filter..........5.4 liters

Manual Transmission,......GL-5/ GL-4 All TEMPS......75W-90
Automatic Transmission,A340E......AF3 / A43D......AF3

Differential, Front/ Rear W/ ADRD......GL-5 ALL TEMPS......75W-90
Differential, Front Less ADRD......GL-5 ALL TEMPS......80W-90

Transfer Case,......GL-4/GL-5 ALL TEMPS......75W-90 Gear oil.

Capacity:
Cooling System, Initial Fill..........8.5 liters
Automatic Transmission, A340E Initial Fill..........1.6 liters
Automatic Transmission, A340F Initial Fill..........2 liters
Automatic Transmission, A43D Initial Fill..........2.4 liters
Automatic Transmission, Total Fill
4 speed A340E..........7.2 liters
4 speed A340F..........10.1 liters
4 speed A43D..........6.5 liters
Manual Transmission, ..........2.5 liters
Differential, With ADRD Front..........1.2 liters
Differential, Without ADRD Front..........1.1 liters
Differential, 2WD V6 Rear..........2.6 liters
Differential, 4WD Extra Long Rear..........2.5 liters
Differential, Short WB With LSD Rear..........2.7 liters
Differential, Short WB Without LS Rear..........2.6 liters
Transfer Case, Electronic..........1.2 liters
Transfer Case, STD..........1 liters

1995 HONDA ACCORD 2.7L 6-cyl Engine Code C27A4 C27A1

Engine Oil Grade 1......API All TEMPS......5W-30
Manual Transmission,......SJ All TEMPS......10W-30, optional 10W-40
Automatic Transmission,MPZA......AF2

CAPACITIES:
Engine, with filter..........4.4 liters
Automatic Transmission, MPZA Initial Fill..........2.7 liters
Automatic Transmission, Total Fill
4 speed MPZA..........6 liters
Manual Transmission, ..........1.9 liters

1995 HONDA ACCORD 2.2L 4-cyl Engine Code F22B1 VTEC

Engine Oil Grade 1......API All TEMPS......5W-30
Manual Transmission,......SJ All TEMPS......10W-30, optional 10W-40
Automatic Transmission,A0YA......AF2

CAPACITIES:
Engine, with filter..........4.3 liters
Automatic Transmission, A0YA Initial Fill..........2.4 liters
Automatic Transmission, MP0A Initial Fill..........2.4 liters
Automatic Transmission, Total Fill
4 speed A0YA..........6 liters
4 speed MP0A..........6 liters
Manual Transmission, ..........1.9 liters

2001 OLDSMOBILE ALERO 3.4L 6-cyl Engine Code [E]
2001 OLDSMOBILE ALERO 2.4L 4-cyl Engine Code [T]

Automatic Transmission,4T45-E......AF6
Automatic Transmission,4T40-E......AF6
Use Low Viscosity ATF, Hight Viscosity ATF or additives create fluid retention which cause the servos, solenoids to seize up causing shifting problems.

CAPACITIES:
Automatic Transmission, 4T45-E Initial Fill..........6.5 liters
Automatic Transmission, 4T40-E Initial Fill..........6.5 liters
Automatic Transmission, Total Fill
4 speed 4T45-E..........12.2 liters
4 speed 4T40-E..........12.2 liters

Good luck and hope this helps.

P0700 (M)
Check Transmission DTC's
This code indicates that the EATX (Transmission controller) has an active fault and has illuminated the MIL via a BUS message. The specific fault must be acquired from the EATX via a DRBIII tool. (Input or Output Speed Sensor failures often cause this code and are a common failure part on WJ Grand Cherokees

P0750
Shift Solenoid circuit.
Note: If code P1767 (Transmission Relay Always On) is also present: Replace transmission solenoid assembly. See note provided. When transmission is in limp mode the relay that provides power to the solenoid group is switched off. This is normal and is designed to provide operation in one gear only. Engineering department suggests to replace transmission solenoid assembly anytime these two trouble codes occur together. See applicable service manual section (21) for solenoid assembly replacement directions. IMPORTANT: When performing this repair always check torque on all valvebody accumulator cover plate screws. Proper torque specification is 70 inch pounds. If any accumulator cover plate screws are damaged or missing replace the valvebody assembly. NOTE: If any other trouble codes are present do not replace solenoid assembly. See test in the applicable Transmission Diagnostic Procedures Manual

P0755
Shift Solenoid B

This code sometimes comes up when the transmission is not shifting in overdrive.

Here is some research that I did and this is wut I found

This code is set whenever in any forward gear with engine speed above 1000 RPM shortly after a shift and every minute thereafter

After a shift into a forward gear, with engine speed > 1000 RPM, the TCM (Transmission Control Module) momentarily turns on element pressure to the clutch that don’t have pressure. For this to be activated, the switch must be closed in order for the circuitry to be completed. If the pressure switch does not close 2 times the code sets.

POSSIBLE CAUSES

RELATED DTC’S PRESENT
TRANSMISSION FLUID LEVEL
INTERMITTENT WIRING AND CONNECTORS
TRANSMISSION CONTROL RELAY OUTPUT CIRCUIT OPEN
2/4 PRESSURE SWITCH SENSE CIRCUIT OPEN
2/4 PRESSURE SWITCH SENSE CIRCUIT SHORT TO GROUND
2/4 PRESSURE SWITCH SENSE CIRCUIT SHORT TO VOLTAGE
INTERNAL TRANSMISSION
TCM - 2/4 HYDRAULIC PRESSURE

My advice to u is get to someone who is experienced about this kind of technology in order for the problem to be rectified.

check for power at the tcm if no power check trans relay