2G Automatic Transmission won’t shift into gear even though it’s in drive

[TreywayMarkus]

So my 1997 Mitsubishi eclipse spyder gst auto, just won’t shift into gear anymore even though the car is in drive or reverse you don’t feel it shifting. Before all this happened, it started irregular shifting when in drive. When coming to a stop, the car would downshift normally but would shift into neutral when stopped even though the gear selector is in drive. It would take a while for it to shift back into first gear from neutral after pressing on the gas. I’m thinking it’s the tcu or the shift solenoids but I’m completely lost. The transmission fluid is fine at the right level with no burning smell. I replaced it back in February. There is no codes.

 

[DogWhistle]

So my 1997 Mitsubishi eclipse spyder gst auto, just won’t shift into gear anymore even though the car is in drive or reverse you don’t feel it shifting. Before all this happened, it started irregular shifting when in drive. When coming to a stop, the car would downshift normally but would shift into neutral when stopped even though the gear selector is in drive. It would take a while for it to shift back into first gear from neutral after pressing on the gas. I’m thinking it’s the tcu or the shift solenoids but I’m completely lost. The transmission fluid is fine at the right level with no burning smell. I replaced it back in February. There is no codes.

That's because the transmission went into 'limp mode'. It's a fail-safe condition should the transmission control unit or transmission solenoids ever fail, then at least you can still drive.

You can check the fluid level again by starting the car and setting the parking brake and then shift into neutral. Now check the fluid level again. The fluid level is not accurate in 'Park' the way some other brands are.

Hopefully it's as simple as low fluid (check for leaks), but otherwise you may have a failed/failing TCU. There are inputs from the ECU that trigger responses from the TCU. Have you done any mods lately?

 

[TreywayMarkus]

That's because the transmission went into 'limp mode'. It's a fail-safe condition should the transmission control unit or transmission solenoids ever fail, then at least you can still drive.

You can check the fluid level again by starting the car and setting the parking brake and then shift into neutral. Now check the fluid level again. The fluid level is not accurate in 'Park' the way some other brands are.

Hopefully it's as simple as low fluid (check for leaks), but otherwise you may have a failed/failing TCU. There are inputs from the ECU that trigger responses from the TCU. Have you done any mods lately?

Hey thanks for the response.

Yes when I checked the fluid before it was done through this procedure to check the fluid. It was done in neutral and the car was running and checked when it was warmed.

Yes I have a TCU coming in, hopefully before end of October. I just thought it might not be the tcu after some research, I heard tcu limp mode allowed you to stay in 3rd gear.

The car is relatively stock except with an Injen air intake and a catback srs exhaust.

 

[jesse12345]

Have you scanned the tcu for codes? I used an old led strip to see which codes I got to flash.

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[Blinkyblinx9]

OKAY! Here we go.

The PRND selection is not electronic on the F4A33 trans. For instance, when you move the gear selector lever from park into the reverse position your moving the selector lever on the transmission via a cable. This lever passes through the trans case and manually operates a valve within the valve body that allows fluid to pass through to engage the associated park, reverse, neutral, and drive clutches and functions.

"Limp mode" locks out all of the control solenoids. The result is that it will be stuck in third, it will operate without pressure regulation, and it will not operate the lockup clutch. Basically it operates as if the TCU were not even there.
Forward clutch disengagement when coming to a stop is typically a sign of a bad pump, a bad pressure regulator valve or solenoid, a bad forward clutch, a clogged filter, or any combination of these issues.

Edit: Fixed a couple errors.
I would also like to add in hindsight that any fluid leaking out of where it needs to be at a rate that was not intended can cause a loss of drive clutch pressure as the RPMs and thus the trans pump wind down at idle and create this symptom. It also may not present this symptom immediately on a cold start as the fluid has not had time to thin out as it heats up.