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In another post, I mentioned that when I am trying to cruise I get a massive stuttering from my drivetrain. My only conclusion is my vehicle's torque converter clutch no longer can actually lockup. I'd like to disable it.

From what I understand, the torque converter clutch is actuated by hydraulic fluid. This hydraulic fluid is controlled by a solenoid valve. An electric current in the coil should cause the solenoid to open, causing a flow of hydraulic fluid.

Is there any reason why I can't just wire a switch somewhere in the transmission harness that allows me to interrupt the current to the solenoid? This should result in the vehicle using 4th gear without the lockup converter. The vehicle has a transmission fluid cooler, so I don't think the additional heat is going to be an issue.

I am guessing the electronics that control this probably check for some current flow, so the switch may actually need to switch between the actual coil in the transmission and a resistor. Is the solenoid connected to +12 V and then the other end is grounded by the computer? Or is the wiring the opposite?

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    You should ensure the TC is what the problem is before you take "drastic" measures. I don't know if it would work for you, but on a previous vehicle I owned with a TC lockup issue, If when you start experiencing the issue, let off the go-pedal just briefly then back onto it, this gives the TC a chance to lock up correctly. This may help Nov 13, 2016 at 16:32

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The torque convertor clutch solenoid shares a power source with the shift solenoids and is grounded by the PCM. You could try unpinning the TCC solenoid signal wire from the transmission connector to disable the solenoid. I'd avoid cutting into the harness if you can. Either way it'll set codes for circuit and performance if you do either of these.

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  • My idea of using a resistor was to avoid throwing the code.
    – Eric Urban
    Nov 13, 2016 at 18:53
  • @EricUrban If the PCM tries to activate the solenoid and nothing happens it'll throw a code for the solenoid or for another corresponding system.
    – Ben
    Nov 13, 2016 at 18:58
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The PCM compares engine speed to vehicle speed. If there is a difference between the two (slippage), the PMC will set code P1870. So, disconnecting the TCC solenoid will prevent lock up, but you'll have to clear the code every time you drive above 50 MPH for a five minute period. All city driving at 45 MPH and under, screw it, disconnect the TCC and call it a day. I'm still looking for a way to get around the code setting issue.

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Changing the transmission output sensor is a cheap and easy fix. Once the sensor gets old it starts giving false readings - it causes code p0741 and a faulty coolant temp sensor will cause the code too.

Flyback is the cause of the sensor failure due to the TCC circuit needing a diode to control flyback voltage spikes that are emitted from the internal shift and torque converter solenoids.

Another thing to note is that every 60,000 miles you need to change your transmission fluid filter. Low fluid pressure could also be the culprit. A free transmission diagnostic check could be in order.

I'd check to make sure all your relays are diode protected especially the fuel pump relay and ECU relay. There's a difference the local Autozone doesn't know about and a simple $13 relay could cause huge issues when not diode protected.

Also make sure your starter solenoid has a diode suppression sticker on it. If it doesn't buy a Diode Suppressed starter solenoid and install it.

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