Changing transmission control modu

Transmission Control Unit - TCI® Auto

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For computer controlled transmissions, nothing beats the TCI® EZ-TCU™Transmission Controller. The EZ-TCU™ allows for maximum electronic control over .

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.

just delt with this one and found it needed a new transmission the tcu most likly is fine. do you have enough ATF in your transmission.

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Very likely could be the TCU (transmission control unit) computer. My Chrysler van had the exact symptom. Costly repair, around $800.

HI. This is a TCU fault. This is intermittently occurring at this time, but it will eventually get worse. You will need to have the TCU scanned for possible transmission trouble codes. I suspect that the TCU will need to be replaced or there may be an issue concerning the solenoid pack. You will need those codes to know for sure.

TCU - Transmission Control Unit

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

it is the Transmission Control Unit. you have to find the reason why the TCU is flashing the D4 fault code. not replace the unit. have your vehicle scanned for another code. your transmission or transaxle is giving you a warning that something is wrong .

check Transmission fluid is very important to an automatic transmission. All of the magic happens in the fluid. Most cars come with red transmission fluid, good to know if you are looking for a leak.

the tcu is on the right ( passenger) side footwell, under the carpet..the carpet has velcro tabs on it that will allow it to be pulled back...once the carpet is back there is a metal cover over the computers that is held on with 4 10mm bolts..take them out and you can remove the tcu!