1999 mitsubishi galant 3.0 v6 not getting 5 volts straight from the tcu/ecu only getting 2.4 volts

These are the same bolt patterns, bolt pattern is 4 X 4.5 or also known as 4 X 114MM. Measure 2 lugholes across from each other and it should measure 4 1/2" US or 114MM. the center hubs may be smaller/larger. Check the center hub size before purchasing:
1997 Acura- CL 16 x 6 (5 straight spokes)
1998 Acura- CL 16 x 6 (5 dual straight spokes)
1998 Acura- CL 16 x 6 (7 straight spokes
1990-89 Acura- Legend 15 x 5.5
1996-95 Acura- TL 15 x 6 (5 straight spokes with groove)
1997-98 Acura- TL 15 x 6 (11 straight spokes)
1994-92 Acura- Vigor 15 x 6 (11 triangular slots)
1999-98 Chevrolet- Metro
1989-85 Chevrolet- Sprint
1991 Dodge- Colt Vista 13 x 5 (15 slots)
1993-92 Dodge- Colt Vista 14 x 5.5 (5 straight spokes)
1992-84 Eagle- Summit/Summit Wagon
1992-91 Eagle- Summit 13 x 5 (15 slots)
1993-88 Ford- Festiva 12 x 4 40mm offset
1993-91 Ford- Festiva 12 x 4.5 40mm offset (8 elongated triangle slots)
1997-89 Geo- Metro
1999-92 Honda- Prelude
1999-90 Honda- Accord (4 cylinder models)
1999-91 Hyundai- Elantra
1995-92 Hyundai- Elantra 14 x 6 (16 slots)
1995-92 Hyundai- Elantra 14 x 5.5 (7 curved spokes)
1998-96 Hyundai- Elantra 14 x 5.5 (5 straight spokes)
1999-90 Hyundai- Accent/Excel/Pony
1994-92 Hyundai- Excel 13 x 5
1991 Hyundai- Sonata 15 x 6 (18 rectangular slots)
1994-92 Hyundai- Sonata 15 x 6 (9 triangular slots)
1996-95 Hyundai- Sonata 15 x 6 (9 straight spokes)
1997-95 Hyundai- Sonata 15 x 6 (5 twisted spokes)
1998-97 Hyundai- Sonata 15 x 6 (5 straight single groove spokes)
1995-90 Hyundai- Scoupe
1992-91 Hyundai- Scoupe 14 x 5 (6 curved spokes)
1995-93 Hyundai- Scoupe 14 x 5 (5 curved spokes)
1998-97 Hyundai- Tiburon 15 x 6 (5 twisted spokes)
1998-97 Hyundai- Tiburon 15 x 6 (5 raised straight spokes)
1989-81 Mazda- 323/GLC
1985-84 Mazda- RX7 GSL-SE 14 x 5.5 40mm offset
1991-86 Mazda- RX7 14 x 5.5 40mm offset
1987-85 Mazda- 626/MX-6
1994-91 Mercury- Capri 14 x 5.5 45mm offset (16 holes)
1994-91 Mercury- Capri 15 x 6 45mm offset (3 curved spokes
1994-91 Mercury- Topaz 14 x 5.5 (16 holes)
1998-92 Mitsubishi- Expo/Expo LRV/Vista Wagon
1994-92 Mitsubishi- Expo 14 x 5.5 (5 straight spokes)
1999-84 Mitsubishi- Galant
1991 Mitsubishi- Galant 14 x 5.5 (18 slots)
1991 Mitsubishi- Galant 15 x 6 (8 straight spokes)
1991 Mitsubishi- Galant 15 x 6 (5 straight spokes)
1993-91 Mitsubishi- Galant 14 x 5.5 (15 slanted spokes)
1992 Mitsubishi- Galant 15 x 6 (5 straight spokes)
1993 Mitsubishi- Galant 15 x 6 (8 triangular and 8 rectangular slots)
1993-84 Mitsubishi- Mirage
1993-91 Mitsubishi- 2000GTX 14 x 5.5 (18 slots)
1991-80 Mitsubishi- Tredia
1999-93 Nissan- Altima
1995-82 Nissan- Stanza
1991-84 Nissan- Maxima
1990-78 Nissan- B310/Pulsar
1989-94 Nissan 240sx
1989-94 Nissan Silvia
1986-82 Nissan- Sentra
1993-84 Plymouth- Colt
1985-79 Plymouth- Arrow/Champ
1999-89 Suzuki- Swift
1991-80 Toyota- Cressida
1985-80 Toyota- Celica

This is what I got for you:
READING DIAGNOSTIC CODES:
1. Connect an analog Voltmeter to the ground and the transmission self diagnosis output pin of the diagnostic connector.
2. Set the ignition switch to "ON".
3. Note the pattern of pulses displayed on the Voltmeter. If the Voltmeter indicates a steady Voltage (either 0 Volts or 12 Volts) the TCU has failed.
4. Refer to the diagnostic codes chart to determine which device is causing the malfunction code.
5. Test and repair the offending components as necessary.
6. Clear the malfunction codes by disconnecting the vehicle battery negative terminal for ten seconds or longer.
7. Road test the vehicle and recheck for newly stored diagnostic codes.
8. After the cause of a failure code has been detected and corrected the diagnostic code memory of the TCU should be cleared by disconnecting the vehicle battery for 10 seconds or more. DIAGNOSTIC CODE INTERPRETATION The Transmission Control Unit monitors operation of the transmission control system. Some components are monitored continuously, others only during specified operating conditions. When the TCU detects a malfunction lasting longer than a specified period of time the TCU will generate an error code that can be detected at the diagnostic connector. If multiple malfunctions occur the diagnostic codes will be sent sequentially beginning with the lowest number code in ascending order with a 2 second pause between each code. A maximum of up to 10 fault codes can be stored in the control unit's memory and the same fault code can be stored as many as three times. If the number of stored codes exceeds 10, previously stored codes will be erased, beginning with the oldest code. The Voltmeter needle will deflect for a particular duration and a certain number of times.
FOR EXAMPLE:
Code 13
The needle will deflect one time for approximately 0.5 second. This will represent one unit of ten. There will be approximately a one second delay and then the needle will deflect three times for approximately 0.2 seconds with 0.1 second delay between deflections. This will represent three units of one.
Code 23
The needle will deflect two times for approximately 0.5 second with approximately 0.3 second delay between deflections. This will represent two units of ten. There will be approximately a one second delay and then the needle will deflect three times for approximately 0.2 seconds with 0.1 second delay between deflections. This will represent three units of one.
If the fail safe system is activated and the trans axle is locked in 3rd gear, a fault code from the fail safe code chart will be stored. Cancellation will occur if, with the trans-axle locked in 3rd gear, the ignition key is turned to the OFF position, the code is stored until cleared. SRSONE.............

Can be a few things. 1) Check the shift solenoids on top of the transmission (front). Remove them and clean out the screens. This would mean your transmission fluid is over due for changing. 2) Maybe it's the Vehicle Speed Sensor (VSS), locate and change that. It's on top of the transmission back under the thermostat area. 3) It could be your Transmission Control Unit (TCU). It's under the floor carpet on your passenger side near the firewall. There is a metal plater covering your ECU and your TCU. The TCU is the smaller box. Remove it, open it and look for burnt items. If you're handy you can replace those items. If you are replacing the unit, make sure it is from a known good one and it matches your car exactly, ie: EX, LX, DX, SE, sport shift button present?, etc... on the circuit board.

Below is a picture of the TCU opened up, here are the transmission codes that your car can display if you are inclined to jump the OBD wire plug to get the reading.

TCU Codes:

CODE LIST:

1-Lock-up solenoid 'A' circuit open or shorted.
2-Lock-up solenoid 'B' circuit open or shorted.
3-Throttle Position Sensor circuit open or shorted.
4-Vehicle Speed Sensor open or shorted - No signal from speedometer.
5-Shift Lever Position Switch circuit shorted.
6-Shift Lever Position Switch circuit open.
7-Shift Solenoid 'A' circuit open or shorted.
8-Shift Solenoid 'B' circuit open or shorted.
9-Counter shaft or transmission speed pulse generator open or shorted.
10-Coolant Temperature Sensor open or shorted.
11-Engine RPM (Ignition coil signal) open or shorted.
12-(No code 12 used)
13-Main shaft speed pulse generator open or shorted.
14-Linear (line pressure control) solenoid open or shorted.
15-Kick down switch circuit shorted.

there are shift soleniods in the transmission that can be change to fix the problem. just you will need know which one

need more specific information on problems being caused by ecu. Has tcu been checked?

Strange that it failed the emission test. The codes given relate to the transmission computer not outputting the correct signals to the engine (power) control module ECU. Have you noticed any abrupt gear shifts lately? I wonder if the emission test failure is related. Sometimes the gear selection failure can be as result of the ECU getting the incorrect information from a faulty throttle position sensor TPS. The ECU relays the information to the transmission controller and this snatches at the gear shift at slightly the wrong time. A faulty TPS might also be responsible for the ECU setting the wrong fuel air mixture and this would result in inappropriate exhaust gas emission. The TPS is on the throttle plate shaft and is located on the outside of the throttle body. The two outer pins on the TPS plug have 0 volts and 5 volts. The middle pin sends the voltage to the ECU according to the throttle shaft position between 0 to 5 volts. Check out the TPS thoroughly before looking for something more complicated. Then next I would pull the sockets from the respective control units and make sure all the contact pins are clean and bright to ensure good inter connection

3.0 V6 engine? Key on, engine off the voltage on the Brown/White wire will be .5 to .75 volts. If its not, loosen the 2 screws and adjust it. 20% at idle is NOT correct. should be at "0"

P1750 Solenoid Assembly Malfunction. The TCU is sending a fail signal to the ECU.
It's more like a transmission problem. Bad solenoid in the transmission.

I have a 95 Eclipse and I recently had to change out my TCU........ Transmission Control Unit, This should be located directly beneath the center console. First I would have the transmission services if problem persist then proceed to changing out the TCU you can get off of ebay. As far as i know there should be 3 Computers in our cars. 1 the Electronic Control Unit located behind radio 2 Transmission Control Unit located under center console and 3 Airbag Control Unit located under hood, Hope this helps.

The transmission is controlled by the Transmission Control Unit (TCU).

Throttle position, rpm, and speed are input parameters to the TCU. The TCU has a default set of shift patterns. These shift patterns change over time based on your specific vehicle setup and driving habbits.

The shift patterns are only slightly affected by driving habbits over many driving cycles. But, changing the relationship between the throttle position and the actual speed being reported by the speed sensor can have an immediate effect on shift patterns.

While your speedo may now be correct, the realtionship between rpm and thottle position has not been corrected. That would take a gear change in the differentials.

The TCU can be reset to an inital learn base line. When this is done, the TCU will instantly learn the dynamics of your setup.

Any shop with an advanced ODB scan tool can reset the the TCU. The dealer or a transmission shop would be preferable.

You really should change your differential gears as opposed to resetting the TCU

This information was posted by ftgiles here