Why monitor torque converter pressure?
An automatic transmission lives and dies by its fluid pressure. The converter's pressure tells you how hard it is being fed, and a change over time is often the first hint of a worn pump, a sticking valve or a failing lockup circuit. Wiring a sensor into your Elite ECU means that pressure is in every log, shows up on your ESP pages and can trigger a fault code before a small problem turns into a rebuild.
This function is monitoring only. If you want the ECU to actually control the converter, see the torque converter control function.
Wiring tab
Assign Gearbox Torque Converter Pressure Input to an AVI or an SPI. We use an AVI whenever one is free, since this is an analog voltage signal. An SPI is the fallback when you've run out of AVIs.
| Setting | What it does | Our advice |
|---|---|---|
| AVI Pull up | Adds a 1k resistor from the input to 5V | Off for a normal 3-wire pressure sensor that has its own 5V supply |
| SPI Sensor Type | How the SPI treats the signal | Set to Hall Effect when reading an analog sensor on an SPI |
| SPI Pull up | Adds a weak 10k resistor to 5V | Same rule as the AVI: off for a powered sensor |
The general rule for pullups: they're meant for two-wire sensors, like most temperature senders, that need the ECU to supply the voltage. A sensor with its own supply doesn't need one. If the sensor is shared with another ECU, such as the factory transmission computer in a piggyback setup, the other unit normally provides the pullup, so leave the Haltech's off.
Calibration tab
The ECU needs to know what voltage equals what pressure. ESP ships with a set of ready-made calibrations, and the default is the one for Haltech's 150 psi pressure sensor. If you're fitting a different sensor, build a custom calibration from the voltage-to-pressure data its manufacturer publishes.
- The yellow folder (Open) icon loads a saved calibration file.
- The blue disk (Save) icon stores your custom calibration so you can reuse it on the next car.
Whatever you load, confirm it against the exact sensor you fit. A mismatched calibration gives believable-looking numbers that are simply wrong. If you need a sensor, the 150 PSI TI pressure sensor is a common choice for this job.
Display tab
- Warning Minimum: below this pressure, torque converter pressure gauges and readouts in ESP flash red.
- Warning Maximum: above this pressure, they flash red for high pressure.
These are visual only. Set them from what a healthy transmission reads in your own logs, so the warning means something when it appears.
Diagnostics tab
Diagnostics set a fault code when the signal leaves a range you define. Every item is disabled by default. When Engine Protection is active you can give each code a DTC severity, which decides how hard the ECU reacts.
| Setting | Code | Triggers when | What it catches |
|---|---|---|---|
| Raw Min | P0847 | Sensor voltage is below your limit | Open circuit or short to ground |
| Raw Max | P0848 | Sensor voltage is above your limit | Short to supply or a broken ground |
| Operating Min | P0846 | Measured pressure is below your limit | A real low-pressure condition |
| Operating Max | P0849 | Measured pressure is above your limit | A real high-pressure condition |
The raw limits look at the voltage, so they catch wiring faults. The operating limits look at the calibrated pressure, so they catch transmission problems. Set raw limits just outside the sensor's normal voltage range, and operating limits outside what you see in healthy logs, with a margin so normal shifts don't trip them.
Troubleshooting
| Symptom | Usually |
|---|---|
| Reading sits at maximum | Pullup left on with a powered sensor, or the signal is open circuit |
| Reading is steady but clearly wrong | Calibration doesn't match the fitted sensor |
| P0847 or P0848 logged | Wiring fault: check the 5V supply, ground and signal at the connector |
| P0846 or P0849 on normal driving | Operating limits set too tight for how the transmission really behaves |
Related transmission sensors: line pressure, gearbox oil temperature and transmission input rpm.
