Ford 2003 Mustang Workshop Manual page 2299

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The TCC solenoid is used to control the apply and release of the TCC.

Shift Solenoid — SSA, SSB

Two on/off shift solenoids provide gear selection of first through fourth gears by controlling the

pressure to the three shift valves. One unit containing the two shift solenoids is located in the main

control valve body. The shift solenoids are two-way, normally open style.

Solenoid Operation Chart

Selector Lever Position PCM Commanded Gear

When a manual pull-in occurs above a calibrated speed, the transmission will not downshift from the

higher gear until the vehicle speed drops below this calibrated speed.

EC = Electronically Controlled

HD = Hydraulically Disabled

Transmission Fluid Temperature (TFT) Sensor

The transmission fluid temperature (TFT) sensor is located on the lead frame assembly near the shift

solenoids on the main control valve body. It is a temperature-sensitive device called a thermistor. It

sends a voltage signal to the PCM. The voltage signal varies with transmission fluid temperature. The

PCM uses this signal to determine whether a cold start shift schedule is necessary. The shift schedule

is compensated when the transmission fluid temperature is cold. The PCM also inhibits (TCC)

operation at low transmission fluid temperatures and corrects electronic pressure control.

Vehicle Speed (VSS) Sensor

The source of vehicle speed (VSS) is model dependent. Possible sources of vehicle speed input are

anti-lock brake sensor (ABS), a gear-driven vehicle speed sensor (VSS), or an output shaft speed

sensor (OSS). The VSS signal is either an A/C signal whose frequency changes with speed, or an

SCP data message depending on the source. Some applications will have both. The vehicle speed

signal is an input to various vehicle subsystems such as the powertrain control module (PCM),

instrument cluster (speedometer and odometer), speed control system, etc. The vehicle speed source

must be operational to enter output state control (OSC) mode for diagnostics.

Regardless of the type of vehicle speed system, the PCM always uses the OSS for transmission and

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