Strangest transmission/ecu problem ever?
08-30-2017, 08:31 PM
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Strangest transmission/ecu problem ever?
Hey guys. I'll try to keep this as short as possible, but it's sorta a long story.
I'll start at the end. According to my scanner, the ECU thinks the TCC brake switch is closed. Even when I hit the brake or pull the entire relay. There is no voltage going to C1 pin33. Scanner also doesn't think we're in 4 low when we are, but the ECM clearly knows we're in low range, because the speedo output and shift points are correct. ECM just thinks the brake switch is closed when it's not, and commands TCC lockup immediately after shifting past 2nd gear (where it just skips 3rd entirely, direct to 4th gear and full TCC lockup, at like, 7km/h).
To the story. 2000 5.3L/4l60e in my 90ish 4Runner. I've done LOTS of these swaps. Never had any issues with them.
Trans felt a little tired. Couple occasional wonky shifts, sometimes having trouble shifting past 2nd, sometimes can't get into reverse. Finally ponied up for a rebuilt/built 60e. Had the builder install a Sonnax reaction shell, vette servo, Transgo HD2 kit, etc. Standard build.
Got it installed. 1-2 shift CRAZY harsh. 2-3 firm, but not killing me. 3-4 boring. TCC seems to want to be locked up earlier than I expect, but I think it was doing that before as well.
Plugged in my shitty InTune tuner to drop the 1-2 shift line pressure. No change. Dropped it as far as it would go (-20%), no change. Flashed back a stock tune. No change. Modifying shift pressures, times, and RPM vs. speed, all works. Just not for the 1-2 shift.
Took it out wheeling for an afternoon. Stuck it in 4 low. Seems okay until it gets ready to shift to 3rd. Doesn't bother with 3rd. Just straight to 4th and locked up the TCC immediately. This of course causes the truck to buck, so it tries to back off the gears a bit, then right back into the lockup. Almost lost it over a cliff because of this.
So what in the hell happened? Did I have a bad ECM the entire time, and it was just coincidence that it got worse the day I installed the new trans, or was the old trans just bad, and the new trans had something internally shorted, which cooked the ECU, or... what? What am I missing? I've asked every rocket scientist I know. No one has a clue.
I'll start at the end. According to my scanner, the ECU thinks the TCC brake switch is closed. Even when I hit the brake or pull the entire relay. There is no voltage going to C1 pin33. Scanner also doesn't think we're in 4 low when we are, but the ECM clearly knows we're in low range, because the speedo output and shift points are correct. ECM just thinks the brake switch is closed when it's not, and commands TCC lockup immediately after shifting past 2nd gear (where it just skips 3rd entirely, direct to 4th gear and full TCC lockup, at like, 7km/h).
To the story. 2000 5.3L/4l60e in my 90ish 4Runner. I've done LOTS of these swaps. Never had any issues with them.
Trans felt a little tired. Couple occasional wonky shifts, sometimes having trouble shifting past 2nd, sometimes can't get into reverse. Finally ponied up for a rebuilt/built 60e. Had the builder install a Sonnax reaction shell, vette servo, Transgo HD2 kit, etc. Standard build.
Got it installed. 1-2 shift CRAZY harsh. 2-3 firm, but not killing me. 3-4 boring. TCC seems to want to be locked up earlier than I expect, but I think it was doing that before as well.
Plugged in my shitty InTune tuner to drop the 1-2 shift line pressure. No change. Dropped it as far as it would go (-20%), no change. Flashed back a stock tune. No change. Modifying shift pressures, times, and RPM vs. speed, all works. Just not for the 1-2 shift.
Took it out wheeling for an afternoon. Stuck it in 4 low. Seems okay until it gets ready to shift to 3rd. Doesn't bother with 3rd. Just straight to 4th and locked up the TCC immediately. This of course causes the truck to buck, so it tries to back off the gears a bit, then right back into the lockup. Almost lost it over a cliff because of this.
So what in the hell happened? Did I have a bad ECM the entire time, and it was just coincidence that it got worse the day I installed the new trans, or was the old trans just bad, and the new trans had something internally shorted, which cooked the ECU, or... what? What am I missing? I've asked every rocket scientist I know. No one has a clue.
10-03-2017, 08:11 PM
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saw no one has replied and figured I would jump in (i know the feeling). If your speedo reads correct then it may not be a vss issue, could be an issue with the ecu seeing a 4 low signal? hard to judge without seeing a tune. Sounds like a trans related electrical issue or something in the tune. Have you checked voltage to pin 33 pressing and not pressing the brake pedal? I believe that that see +12 when your foot is off the pedal and 0v when your foot is on.