For 1990-2009 cars

### Transmission Output Speed Sensor

The Transmission Output Speed sensor (1) is mounted in the side of the transmission extension assembly, and works in conjunction with the parking lock wheel. The parking lock wheel is splined to the output shaft and has teeth on its outside diameter.

The speed sensor assembly consists of a permanent magnet surrounded by a coil of wire. As the output shaft and parking lock wheel rotate, an alternating current (AC) is induced in the coil of wire by the teeth on the parking lock wheel passing by the magnetic pickup. The TCM interprets this AC signal as output shaft speed.

### Transmission Fluid Temperature Sensor

The Transmission Fluid Temperature (TFT) sensor contains a semiconductor device which changes resistance based on temperature (a thermistor). The TFT sensor is located inside the transmission in the main case wiring harness. The TFT sensor has a signal circuit and a ground circuit. The TCM applies a voltage (about 5.0 volts) on the signal circuit to the sensor. The TCM monitors changes in this signal voltage. The TCM interprets the resulting change in the resistance of the sensor and determines the transmission fluid temperature.

When the fluid is cold, the sensor (thermistor) resistance is high, and the TCM's signal voltage is only pulled down a small amount through the sensor to ground. Therefore, the TCM will sense a high signal voltage (low temperature). When the fluid is warm, the sensor resistance is low, and the signal voltage is pulled down a greater amount. This causes the TCM to sense a low signal voltage (high temperature).

### Transmission Range Switch

Important: Align the Transmission Range switch with the selector shaft upon each removal and installation of the switch in order for the Transmission Range switch to function properly. Refer to On-Vehicle Service, Transmission Range Switch for the specific procedure.

The Transmission Range switch signals to the TCM which position the gear selector lever is in. The Transmission Range switch bolts to the outside of the main transmission case and splines to the transmission selector shaft.

### Throttle Position

The TCM receives the throttle position from the ECM. This data is part of the PWM ECM Data Signal to the TCM. This signal processes within the TCM and several parameter values within the PWM signal separate out. The TCM uses the information on the throttle position to determine the appropriate shift patterns, shift feel and TCC apply and release timing. In general, with greater throttle angle and higher TPS voltage signal, the TCM delays upshift speeds (through shift solenoid control) and increases the line pressure (through force motor solenoid control). Also, the TCM keeps the converter clutch released at minimum throttle positions and during heavy acceleration. Refer to Engine Controls, Driveability and Emissions for more information.

### Engine Speed

A processed CKP sensor signal is sent to the TCM from the ECM. The TCM calculates the engine speed from this signal. Use this data in order to help determine the shift patterns and the TCC apply and release timing.

### Engine Coolant Temperature

The TCM receives the engine coolant temperature from the ECM. This data is part of the PWM encoded ECM Data Signal to the TCM. This signal processes within the TCM and several parameter values within the PWM signal separate out. The TCM prevents converter clutch apply when engine coolant temperature is below approximately 70°C (158°F).

### Brake Switch

This switch causes the TCM to command TCC release. When the brake pedal is depressed, the TCM opens the path to ground for the TCC solenoid electrical circuit. This de-energizes the solenoid and releases the converter clutch.

### Wide Open Throttle Switch

This switch is part of the accelerator cable underhood. The wide open throttle switch signals the TCM when the accelerator pedal is fully depressed. The wide open throttle switch closes when the accelerator pedal travel goes beyond the equivalent of approximately an 80 percent throttle angle.

### A/C Request Signal

When the A/C compressor is on, a signal is sent to the TCM. The TCM adjusts the transmission line pressure and the shift timing in order to compensate for the added load on the engine.

### Sport Mode Switch

Depressing this push-button changes the transmission operating mode between the Economy and Sport driving modes. In the Sport mode, the TCM delays part-throttle upshifts for greater acceleration. The TCM also signals the force motor solenoid to increase the line pressure for the additional torque requirements in the Sport mode. The higher line pressure creates firmer shifts and more holding force for the friction clutches and the brake band. The Economy mode provides better fuel economy by having the TCM initiate earlier part-throttle upshifts. Also, in the Economy mode, the line pressure is lower in order to provide smoother upshifts and downshifts.

### Winter Mode Switch

In the Winter mode, the TCM changes the shift solenoid states in order to start the transmission in 3rd gear. By starting to move the vehicle with the transmission in 3rd gear, less torque is created, thereby reducing tire slippage on ice and snow. When the driver selects the Winter mode, the TCM overrides the selection of the Economy or the Sport modes. The TCM only enters the Winter mode when the following conditions are met:

• | The selector lever is in the Drive Range (D).

• | The vehicle speed is less than 10 km/h (6 mph).

• | The transmission fluid temperature is less than 130°C (266°F).

• | The wide open throttle (WOT) switch is off and throttle opening is less than 7 percent.

The Winter mode cancels if any of the following conditions are met:

• | The Winter mode button is depressed.

• | The selector lever is moved to the Park position or the lower drive ranges (the TCM will remain in Winter mode in Neutral and Reverse).

• | The ignition key is off.

• | Transmission fluid temperature is greater than 130°C (266°F).

• | The wide open throttle (WOT) switch is activates.

When the Winter mode cancels due to one of these conditions, the TCM returns to operating in Economy mode, regardless of the operating mode before selecting Winter mode.